Micro/Parasites

In observing the slow-growing, 7-day-old dark brown colonies growing on Sabouraud Dextrose with Brain Heart Infusion (SABHI) agar, note that the black pigment extends to the reverse of the colony. This provides a presumptive indication of one of the fungi involved in chromoblastomycosis. The species identification of this fungus can be made by observing the distinctive fruiting heads illustrated in the bottom image. Select the identification of the fungal species. The correct answer is highlighted below a)Fonsecaea pedrosoi b)Exophiala jeanselmei c)Phialophora verrucosa d)Cladophialophora carrionii

c) Phialophora verrucosa Phialophora verrucosa is the correct response. Observed microscopically is the Phialophora type sporulation, characterized by individual phialides that have an urn-shaped terminal ending (arrows) from which ball-like clusters of small, spherical conidia are being produced, leading to the identification of P. verrucosum.

What is minimal media for CSF?

Chocolate plate to screen for nieserria and haemophullis

What is CNA used for?

Growth of gram positive organisms Contains colistin and nalidixic acid

The colony illustrated in the top image developed after 4 days of growth on Sabouraud's dextrose agar. Note the extension of the outer margin to the rim of the Petri dish. The bottom image 2 is a methylene-blue stained image of an inoculum obtained from the surface of the colony. From these characteristics, select the fungus genus from the multiple choices. The correct answer is highlighted below TrichodermaFusariumAcremoniumGliocladium

Trichoderma Trichoderma is the intended selection. The border to border extensions of the colony is similar to those of Gliocladium except the surface pigmentation is light yellow green rather than deep green. Microscopically observed are small rather than large dense clusters of spherical conidia, here located at the tips of short conidiophores that are projected laterally from the hyphae.

What organism is associated with canine or feline bites?

Pasteurella multocida

Simmon's citrate has what additives?

inorganic sodium citrate as a source for carbon, and ammonium phosphate, which serves both as a buffer and as a source of nitrogen

What is in the early stage of nematode life cycle that looks like a worm? How do you differentiate between them?

microfilarae arrangement of nucli and absence or presence of a sheath

What organisms produce H2S on TSI?

proteus, edwardsiella, salmonella P.Ed.S PEdS

What organism displays an "Arrow-head" on agar?

streptococcus agalactiae

Phialophora

what kind of sp demonstrates this morphology looks like a vase or urn

Cefsulodin-irgasan-novobiocin (CIN) agar selectively grows what?

Yersinia enterocolitica

Steam autoclave uses what for sterilization?

121 C 15 mins at 15lbs of pressure

This parasite, found in stool, measures 60 µm by 45 µm. Name that parasite A)Diphyllobothrium latum egg B)Fasciolopsis buski egg C)Paragonimus westermani egg D)Schistosoma japonicum egg

A Diphyllobothrium latum Diphyllobothrium latum is the correct answer. D. latum has an average size of 65 by 48 µm. D. latum can be recognized by its size and the presence of a small terminal knob opposite a prominent operculum. This organism is commonly known as the broad fish tapeworm. As the common name indicates, infection with D. latum occurs following ingestion of contaminated fish.

The morphology of this cyst resembles Entamoeba histolytica, but lacks ingested red blood cells in its trophozoite form. What is this organism? A)Entamoeba hartmanni B)Entamoeba coli C)Entamoeba gingivalis D)Endolimax nana

A)Entamoeba hartmanni The correct answer is Entamoeba hartmanni. Entamoeba histolytica and Entamoeba hartmanni trophozoites typically contain central karyosomes surrounded by evenly distributed peripheral chromatin, but Entamoeba hartmanni does not ingest red blood cells.

Identification of intestinal microsporidial spores is usually done by using which of the listed stains? A)Modified trichrome stain B)Modified acid-fast stain C)Gram stain D)Giemsa stain

A)Modified trichrome stain Modified trichrome stain is the stain of choice for identifying intestinal microsporidium spores

This egg measuring 112 µm by 55 µm, was recovered from a sputum sample. What is the correct identification of this organism? A)Schistosoma mansoni egg B)Paragonimus westermani egg C)Pneumocystis jiroveci cyst D)Diphyllobothrium latum egg

B) Paragonimus westermani egg is the correct answer because out of all the parasites listed, this species is the only fluke egg known to be found in human sputum. Diagnosis is made by the characteristic size (80-120 µm x 45 - 60 µm), shape (oval), color, (yellow-brown), and the presence of an operculum.

A medium that can be used to recover Francisella tularensis is: A) Bordet-genou AGAR B) Buffered charcoal yeast extract agar C) Loeffler agar D) mac agar

B) Buffered charcoal yeast extract agar Francisella needs cysteine to grow, buffered charcoal yeast extract is cysteine rich

Which culture medium is specifically formulated to recover Salmonella typhi from stool specimens? A)Selenite broth B)Bismuth sulfite agar C)Salmonella/Shigella (SS) agar D)Deoxycholate citrate agar

B)Bismuth sulfite agar The correct answer is bismuth sulfite agar. Bismuth sulfite agar is a peptone enriched agar that contains bismuth sulfite and brilliant green which serve as inhibitors of most enteric bacteria except Salmonella typhi, and other salmonellae.

The infective stage for the majority of all intestinal amebae is the: A)Trophozoite B)Cyst C)Larva D)Egg

B)Cyst The cyst is the infective stage for most amebae. The cyst is nonfeeding and environmentally resistant. It is the infective stage. Infections are generally caused by ingestion of the cyst stage.

Illustrated in the photograph is the 4-day slow growth of colonies recovered on an anaerobic culture. Note the small size of the colonies growing on anaerobic blood agar, distinctive for brown-black pigmentation surrounded by a wide zone of beta hemolysis. Gram stain revealed small, gram-negative coccobacilli. Most strains are biochemically inactive, although glucose and lactose fermentation are positive (saccharolytic). A common source would be from an infection of the oral cavity or from an infected human bite wound. From these observations, select from the multiple choices the identification of this isolate. A)Veillonella parvula B)Prevotella melaninogenica C)Bacteroides fragilis D)Fusobacterium nucleatum

B)Prevotella melaninogenica Prevotella melaninogenica is the correct response. The presumptive identification can be suspected from the observation of black-pigmented colonies, suggested by the species name. The presence of broad zones of beta hemolysis surrounding the colonies is also distinctive. Small gram-negative coccobacilli lying singly are observed on gram stains. Most biochemical reactions are negative with the exception of the fermentation of glucose and lactose. P. melalinogenica is endemic in the oral cavity and may be recovered from cultures obtained from dental cavity infections. Isolates have also been recovered from human bite wounds.

Which of the following is a nonfermenter? A)Escherichia coli B)Pseudomonas aeruginosa C)Yersinia enterocolitica D)Serratia marcescens

B)Pseudomonas aeruginosa Nonfermenting Gram-negative rods fail to acidify an oxidative-fermentative (OF) medium when it is overlaid with mineral oil or fail to acidify triple sugar iron agar (TSI) butts. Pseudomonas aeruginosa is the only nonfermenter listed.

Typically an uncommon isolate in clinical laboratories, this gray-white colony with a hairy mycelium as illustrated in the top image is non-specific. The identification is made by microscopically observing acid-fast ascospores as seen in the bottom image. Select the fungal species characteristic of this isolate. A)Malassezia furfur B)Wickerhamomyces anomalus (Hansenula anomala) C)Aureobasidium pullulans D)Saccharomyces cerevisiae

B)Wickerhamomyces anomalus (Hansenula anomala) Wickerhamomyces anomalus (sexual state; formerly Hansenula anomala) have acid-fast ascospores (arrow) that are distinctive for being flattened on one side with a distinct outer lip simulating the derby hat of an English "bobby". Although usually considered as a commensal or a contaminant, isolated infections have been found in hospitalized patients commonly associated with indwelling catheters, particularly in those who are immunosuppressed.

non-hemolytic colony and has a tenacious consistency, similar to whisked egg whites, Gram-positive bacillus

Bacillus anthracis

Loeffler's medium is useful in making the presumptive identification of isolates suspicious for Corynebacterium diphtheriae recovered from oropharyngeal cultures because it: A)Inhibits the growth of contaminating bacteria B)Detects the production of H2S C)Enhances granule formation as seen in methylene blue stains D)Screens out the toxin producing strains

C)Enhances granule formation as seen in methylene blue stains Although the identification of Corynebacterium diphtheriae in upper respiratory specimens cannot be made by the study of direct smears, the accentuated granule formation seen in methylene blue stains of isolates grown on this medium is a helpful property in determining which strains should be further studied, either by subculture to tellurite medium or for toxicity studies.

A recto-sigmoidoscopy revealed pseudomembranes in a patient with severe diarrhea following prolonged treatment with ampicillin. Which of the following organisms is MOST likely to be isolated? The correct answer is highlighted below a)Bacteroides fragilis b)Clostridium botulinum c)Clostridioides difficile d)Fusobacterium nucleatum

Clostridioides difficile is a gram-positive, anaerobic, spore-forming bacillus that produces a strong toxin. C difficile is a common cause of antibiotic-associated diarrhea and pseudomembranous colitis.None of the other organisms are associated with pseudomembranous colitis.

Clenched-fist cellulitis is commonly found in patients who have been in a physical altercation. Which organism below is the most likely cause of this condition? A)Neisseria gonorrhoeae B)Staphylococcus aureus C)Streptococcus anginosus group D)Eikenella corrodens

D)Eikenella corrodens The correct response is Eikenella corrodens as it is a normal flora of the mouth and those that have been in an altercation and have punched someone in the mouth, can often become infected with this bacteria.

Vibro parahaemolyticus is best isolated from feces how? A) eosin methylene blue agar (EMB) B) Hektoen agar C) Salonella shigella agar D) thiosulfate citrate bile salts

D) thiosulfate citrate bile salts

(NO PICTURE) The distinctly large, spreading, mucoid colonies seen on blood agar in the upper left image, and the display of lactose fermentation on MacConkey agar in the upper right image provide for a presumptive organism identification. This species is most commonly recovered from respiratory specimens of patients with pneumonia. Observing the absence of motility, a weak reaction for urea, and strong reactions for citrate and Voges-Proskauer confirm the presumptive identification. From the multiple choices, select the name of the isolate presented here. A)Proteus mirabilis B)Edwardsiella tarda C)Citrobacter freundii D)Klebsiella pneumoniae

D)Klebsiella pneumoniae Klebsiella pneumoniae is the correct response. The large, distinctly mucoid appearance of the colonies with evidence of lactose fermentation on MacConkey agar provides for a presumptive identification of K. pneumoniae. Observing a weak reaction for urea, and strong reactions for citrate and Voges-Proskauer help to confirm the identification. Klebsiella species are also non-motile. As the species name indicates, this isolate is commonly recovered from patients with pneumonia.

All of the following Mycobacterium species produce pigments, EXCEPT? A)Mycobacterium scrofulaceum B)Mycobacterium marinum C)Mycobacterium kansasii D)Mycobacterium fortuitum group

D)Mycobacterium fortuitum group Mycobacterium fortuitum group consists of several species that are similar including M. fortuitum, and M. peregrinum. M. fortuitum is commonly isolated in the environment and is implicated frequently in skin and soft tissue infections. M. fortuitum does not produce pigments in light or dark and is, therefore, the correct answer.

an intestinal amoeba acquired through contaminated food and water found in stool specimens

Entamoeba hartmanni

This trichrome-stained organism measuring 15 µm was found in a stool sample. What is the identification of this parasite? The correct answer is highlighted below A)Entamoeba histolytica B)Entamoeba hartmanni C)Entamoeba coli D)Artifact

Entamoeba histolytica

This parasite is more commonly found in rats and mice

Hymenolepis diminuta

Strep Group F

Streptococcus anginosus

The photograph on the right is of a 5% sheep blood agar plate inoculated with a throat culture. It is common practice to stab the agar with the inoculating needle, as seen at the tip of the arrow, in order to detect or accentuate the reaction of: A)Streptolysin O B)Streptolysin S C)Lecithinase D)Alpha prime hemolysin

Streptolysin O The practice of stabbing the agar in areas of inoculation has the effect of submerging the growing bacteria under the surface of the agar, where conditions are relatively anaerobic. Oxygen labile hemolysin or streptolysin O (SLO) is observed only under anaerobic conditions; therefore, will appear in the stab areas, accentuating the intensity of the hemolytic reaction as seen in this photograph. Streptolysin S (SLS) is the oxygen stable form of hemolysis seen around colonies when incubated aerobically. SLO and SLS are produced by Streptococcus pyogenes, the causative agent of strep throat.

Musty basement odor

Streptomyces species Actinomycetes

Illustrated in this image is a single proglottid representative of one of the cestode tapeworms. This proglottid is longer than wide and has well over 13 lateral uterine branches. Select the presumptive identification of this tapeworm. The correct answer is highlighted below Taenia soliumTaenia saginataDiphyllobothrium latumDipylidium caninum

Taenia saginata is the correct response. This proglottid, being longer than wide, is distinctive for having greater than 13 lateral uterine branches, which serves to rule out the other cestodes listed in this exercise. (beef tapeworm)

What organism has oval-shaped micro-conidia that are directly attached in parallel on either side of thin hyaline hyphae by short, delicate laterally projecting conidiophores

Trichophyton rubrum

The upper image depicts a small circular white colony with a downy surface, recovered from a skin scraping specimen after 7 days of growth on agar supplemented with thiamine and inositol. The identification is made by observing the aerial hyphae (middle image) and the underlying chains of pigmented chlamydospores among the hyphae (lower image). Based on this information, what is the most likely identification of this dermatophyte? The correct answer is highlighted below Microsporum gypseumTrichophyton tonsuransTrichophyton verrucosumEpidermophyton floccosum

Trichophyton verrucosum exhibits a small-growing white downy colony that is not distinctive. The indication that the colony grew on agar containing thiamine and inositol may be a clue that one of the Trichophyton species, particularly T. verrucosum was suggested. The antler-type hyphae and the chains of darkly pigmented chlamydospores as observed along the underlying hyphae indeed are the microscopic features for T. verrucosum.

The following test may be performed on all swarming Proteus species to differentiate between Proteus mirabilis and Proteus vulgaris: a)Catalase b)Indole c)Oxidase d)Motility

b)Indole The indole test is useful in differentiating Proteus mirabilis (indole negative) from Proteus vulgaris (indole positive).

A county experinces diarrhea out break due to heavy rains and flooding. What should you use to culture stool specimens? a)colistin nalidixic acid for Listeria b)Mac with sorb. for Campylobacter c)Mannitol salt agar for Enterrococcus d)Thiosulfate citrate bile salts sucrose for Vibrio species

d)Thiosulfate citrate bile salts sucrose for Vibrio species

What organism matches the tissue morphological features of separate hyphae, 5-10 µm in diameter that exhibit dichotomous branching? a)Aspergillus species b)Histoplasma capsulatum c)Blastomyces species d)Coccidioides species

a)Aspergillus species Aspergillus species morphologic features in tissue are septate hyphae 5-10 µm in diameter that exhibit dichotomous branching

Illustrated in this photomicrograph is the tail portion of an adult worm of a filarial nematode in a peripheral blood smear. These worms measure up to 300 µm in length and commonly inhabit the lymphatics of the inguinal region resulting in swelling below the knee in what is known as "elephantiasis". What is this species pictured, which can be presumptively determined by the orientation of nuclei within the tail section (arrows)? a)Brugia malayi b)Wuchereria bancrofti c)Loa loa d)Dirofilaria immitis

a)Brugia malayi Brugia malayi has the distinctive extension of two nuclei into the tail section, separated from one another by an open space. The adult worms more commonly inhabit the lymphatics of the inguinal region resulting in swelling below the knee, a condition known as elephantiasis.

A 4-day old colony recovered on Sabouraud's dextrose agar is illustrated in the top photograph. The specimen was taken from a skin infection incurred by a 45-year-old farmer. The microscopic appearance obtained from the surface mycelium of the colony is illustrated in the lactophenol blue mount in the bottom image. What is the identification of this fungal isolate? The correct answer is highlighted below a)Epidermophyton floccosum b)Microsporum gypseum c)Microsporum canis d)Trichophyton mentagrophytes

b)Microsporum gypseum Microsporum gypseum grows a distinct cinnamon-brown pigmented colony that develops with outward projecting hyphal strands. As conidia are produced, the mycelia surface becomes granular from the production of abundant conidia, and hair-like extensions are observed from the colony periphery. In stained microscopic mounts, large multi-celled, canoe-shaped, smooth-walled macroconidia are observed, with the distal cells being rounded rather than with a tapered tip. M. gypseum is a geophilic dermatophyte, so skin infections are usually contracted from direct contact with spore-infected soil.

Which would be acceptable for anaerobic culture? a) vaginal swab, eye swab b)intraoral surface swab, leg tissue c) pleural fluid, brain abscess fluid d) urine, sputum

c) pleural fluid, brain abscess fluid

Illustrated in the top photograph is a 4-day growth of silky, light gray-white to yellow colonies grown on Sabouraud's dextrose agar incubated at 30° C, recovered from an "athlete's foot" infection (tinea pedis) of a young football player. Note the projection of delicate hyphae to the periphery of the colonies. The identification can be made by observing the conidia formations in the lactophenol blue-stained mount prepared from the surface of one of the colonies. With these observations, select the species identification from the multiple choices. a)Trichophyton mentagrophytes b)Trichophyton tonsurans c)Epidermophyton floccosum d)Microsporum gypseum

c)Epidermophyton floccosum Epidermophyton floccosum is the correct selection. The silky gray-yellow colonies with outward projecting delicate hyphal strands are highly suggestive of E. floccosum. The more definitive identification is made by observing the microscopic appearance of the three to five celled macroconidia that are typically large and club-shaped with smooth walls and attached directly and laterally from hyaline hyphae. Microconidia are never produced. E. floccosum is an anthropophilic dermatophyte that is an important cause of tinea cruris (jock itch) and tinea pedis (athlete's foot).

An infective agent of skin wound infections and an agent of toxic shock syndrome, the large, entire, golden-yellow, smooth convex colonies on blood agar were recovered from a swab specimen after 48 hours incubation at 37o C. In the image to the right, clusters of gram-positive cocci were observed microscopically in a gram stain prepared from one of the colonies. The coagulase reaction was positive. With these observations, select the name of this isolate from the choices given. A)Staphylococcus aureus B)Staphylococcus saprophyticus C)Micrococcus luteus D)Rothia mucilaginosis

A)Staphylococcus aureus

Which of the following Streptococcus spp. exhibits a positive bile solubility test? A)S. pyogenes B)S. pneumoniae C)S. agalactiae D)S. mutans

B)S. pneumoniae The correct answer is Streptococcus pneumoniae. Streptococcus pneumoniae has many distinguishing characteristics, including sensitivity to Optochin, colonies dissolve with the addition of sodium deoxycholate (positive bile sensitivity test) and colonies are typically alpha-hemolytic with wither a dipped center or mucoid capsule. It is most commonly implicated as the cause of pneumonia. S. pyogenes, S. agalactiae, and S. mutans are all bile solubility negative.

Examine the following test results and identify what action you would take. CAMP: Arrowhead appearance Bacitracin disk: 6mm zone of inhibition PYR: Negative Bile Esculin: Tan appearance, no darkening A)Report the isolate as Streptococcus pyogenes B)Repeat the PYR test because you would expect it to be positive in this case C)Report the isolate as Streptococcus agalactiae D)Perform a 6.5% NaCl tolerance test to rule out Enterococcus species

C)Report the isolate as Streptococcus agalactiae Streptococcus agalactiae is the most likely organism because of the positive CAMP test (an arrowhead of beta hemolysis is positive; no arrowhead is negative). The other test results further confirm Strep agalactiae as the correct choice.

The organism depicted in the image to the right is found as normal flora of the mouth, GI, and genital tracts; it is known to cause a chronic disease that exhibits abscesses, tissue fibrosis, and draining sinuses. What is the name of this chronic disease? A)Nocardiosis B)Sporotrichosis C)Borreliosis D)Actinomycosis

D) Actinomyces spp. is a gram-positive non-spore-forming bacilli. It is found as normal flora in the mouth, GI, and genital tracts. Actinomycosis is the term for chronic diseases caused by Actinomyces spp. There are thoracic, abdominopelvic, and central nervous system forms of the disease, but the most common type involves the face and neck.

The colonies illustrated in the photograph on the surface of an anaerobic blood agar plate are relatively small, measuring 1 - 2 mm in diameter, round, smooth with a shiny surface, and are non-hemolytic. The Gram stain photomicrograph reveals small Gram-positive bacilli in short chains and loose diphtheroidal-like clusters. The indole reaction was found to be strongly positive. This isolate is part of the normal flora of the skin, nasopharynx, oral cavity, and gastrointestinal and urinary tracts. It is commonly recovered as a contaminant from blood cultures, but on occasion may be the cause of skin and shunt infections. From these observations, select the presumptive identification of this isolate. A)Bifidobacterium species B)Clostridium septicum C)Actinomyces israelii D)Cutibacterium (Propionibacterium) acnes

D)Cutibacterium (Propionibacterium) acnes Cutibacterium (Propionibacterium) acnes is the correct response. Colonies after anaerobic incubation on blood agar are small, enamel white, circular and opaque. Hemolysis is not observed. Observed in Gram stains are Gram positive coccobacilli that are arranged singly, in short chains, and more distinctly in diphtheroidal clusters. Indole and catalase reactions are positive. Except for fermentation of glucose, carbohydrate fermentation is negative (asaccharolytic). P. acnes most often may be a culture contaminant, but on occasion serve as the cause of skin wound and shunt infections

All of the following statements about Coxiella burnetii are true, EXCEPT: A)It causes Q fever B)It has a worldwide distribution C)It is an obligate intracellular organism D)It is best diagnosed by culturing of the organism

D)It is best diagnosed by culturing of the organism All of the following statements about Coxiella burnetii are true, EXCEPT: The correct answer is highlighted below It causes Q feverIt has a worldwide distributionIt is an obligate intracellular organismIt is best diagnosed by culturing of the organism

What is recommended to diagnose latent and active infections of M. tuberculosis

enzyme-linked immunosorbent assay

When administering fresh frozen plasma (FFP), which one of the following is considered standard blood bank practice? a)Should be ABO compatible with the recipient's red blood cells b)Must be the same Rh type as the recipient c)Is appropriate for use as a volume expander d)Component should remain frozen when it is issued

a)Should be ABO compatible with the recipient's red blood cells FFP should be ABO-compatible with the recipient's red blood cells, but does not need to be the same Rh type as the recipient because it is a cell-free product.

Which organism is MOST likely responsible for septic reactions associated with red blood cell transfusions? a)Yersinia enterocolitica b)Escherichia coli c)Enterobacter species d)Streptococcus species

a)Yersinia enterocolitica The transfusion of small amounts of bacterially contaminated blood can be fatal or cause serious morbidity. Any contaminating bacteria in the donor unit that are unable to survive at 4oC die after several days of storage. Yersinia enterocolitica can thrive at 4oC and it can promote transfusion reactions.

How would you collect a urine from a patient with an indwelling catheter?

aspirate urine aseptically from the catheter tubing

Where can sentinel laboratory staff find the standardized testing protocols? a)Centers for Disease Control (CDC) website b)American Society for Microbiology (ASM) website c)Laboratory Response Network (LRN) website d)FEMA

b)American Society for Microbiology (ASM) website The CDC established, with the Federal Bureau of Investigation, the LRN system for detecting and reporting possible bioterrorism agents. The LRN website is the three-tiered system of detecting, confirming, characterizing and reporting possible bioterrorism agents. FEMA (Federal Emergency Management Agency) has the lead role in consequence management.

The fungal colonies illustrated on the left image grew to maturity in 4 days. The isolate was recovered from the expectorated sputum of an elderly immune-compromised patient. The image on the right is the microscopic appearance of a lactophenol cotton blue-stained mount prepared from a small sample from the surface of the colony. Note that microscopically the entire surface of a smooth spherical vesicle is surrounded by a row of phialides giving rise to small conidia. Which Aspergillus species is represented by these observations? a)Aspergillus fumigatus b)Aspergillus flavus c)Aspergillus niger d)Aspergillus terreus

b)Aspergillus flavus Aspergillus flavus is the correct selection. Colonies of A. flavus are granular to wooly with some shade of yellow or yellow-green. On microscopic examination, the entire spherical vesicle is covered with phialides which give rise to elliptical or spherical conidia.

Laboratory diagnosis techniques that utilize water are NOT recommended for the identification of which of these parasites? a)Cryptosporidium parvum b)Blastocystis hominis c)Toxoplasma gondii d)Balantidium coli

b)Blastocystis hominis Laboratory diagnosis techniques utilizing water, as well as several other solutions, is not recommended for the recovery of Blastocystis hominis because these solutions are known to lysate the vacuolar, multivacuolar, and granular forms of this parasite leading to false-negative results.

Which of the following test is the most useful in differentiating Listeria monocytogenes from Erysipelothrix rhusiopathiae? a)Nitrate production b)Catalase production c)Urease production d)Glucose fermentation

b)Catalase production Catalase production is the only test listed that differentiates Listeria monocytogenes from Erysipelothrix rhusiopathiae. L. monocytogenes is catalase positive, where E. rhusiopathiae is catalase-negative.

This image is a Trichrome-stained protozoan measuring 25 µm that was found in a stool specimen. Which of the following does this image represent? a)Iodamoeba butschlii trophozoite b)Entamoeba coli trophozoite c)Endolimax nana trophozoite d)Entamoeba histolytica trophozoite

b)Entamoeba coli trophozoite Entamoeba coli trophozoite is the correct answer due to the size, uneven peripheral chromatin, and eccentric karyosome.

Which strictly human pathogen causes chancroid, a highly contagious, sexually transmitted genital ulcer disease? The correct answer is highlighted below a)Treponema pallidum subsp. pallidum b)Haemophilus ducreyi c)Chlamydia trachomatis d)Neisseria gonorrhoeae

b)Haemophilus ducreyi Haemophilus ducreyi is the causative agent of chancroid, or soft chancre. H. ducreyi is the only Haemophilus species that is not part of normal human flora

The fungal colony illustrated in the upper image, observed after 4 days of incubation at 30°C, was recovered from dialysis fluid of a 60-year-old patient who had been receiving multiple antibiotics for treatment of bacterial peritonitis. The colony surface is cottony and green in pigmentation. The lower image is of a lactophenol cotton blue-stained section of fruiting heads observed in a mount prepared from a small sample of the colony surface. Based on the colony morphology and microscopic features, what is the genus identification of this isolate? a)Paecilomyces b)Penicillium c)Scopulariopsis d)Fusarium

b)Penicillium Penicillium is the correct response. Characteristic are fruiting heads in the form of a "penicillus" each at the tip of a conidiophore that branches into primary metulae from which in turn are produced secondary phialides. Long chains of small, spherical conidia are produced from the blunt tips of the phialides.

Which bacterial species is most likely represented by the spreading, gray-white, beta-hemolytic colonies with a "frosted glass" appearance as illustrated in the photograph? a)Burkholderia pseudomallei b)Listeria monocytogenes c)Bacillus cereus c)Streptomyces anulatus

c)Bacillus cereus Bacillus cereus colonies are characteristically spreading, gray-white, and beta hemolytic, with a "frosted glass" appearance.

From the list of fungal species below, select the one that requires the use of an enriched agar base such as inhibitory mold agar, SABHI (Sabouraud's dextrose agar + heart infusion agar), or brain-heart infusion with cycloheximide and chloramphenicol. a)Aspergillus terreus c)Cryptococcus neoformans c)Blastomyces dermatitidis d)Fusarium species

c)Blastomyces dermatitidis Blastomyces dermatitidis is the correct answer because as one of the dimorphic fungi, this species would require one of the selective media necessary for their recovery in culture. The addition of cycloheximide and or chloramphenicol to the media is recommended for the culture of certain specimens to inhibit the growth of rapidly growing fungi that may prevent the recovery of the slower growing dimorphic species.

Which Gram-negative organism can produce "gliding motility" on agar plates and is a primary cause of juvenile periodontitis? a)Eikenella corrodens b)Aggregatibacter actinomycetemcomitans c)Capnocytophaga ochracea d)Fusobacterium nucleatum

c)Capnocytophaga ochracea The association of children, teeth, and "gliding" (referring to the unique motility seen on agar plates) all point to Capnocytophaga ochracea, one of the primary causes of localized juvenile periodontitis, an aggressive dental disease that leads to the destruction of teeth and the underlying alveolar bone. A variety of factors lead to this progressive disease, including the production of substances that inhibit neutrophil function, proteolytic enzymes, and penetration of the deeper tissues through its unique gliding motility.

Different species of Neisseria can be differentiated from each other by: a)Oxidase test b)Catalase test c)Carbohydrate utilization d)Nitrate reduction test

c)Carbohydrate utilization Carbohydrate utilization tests are usually employed to identify various Neisseria sp. Rapid carbohydrate testing utilizes a heavy inoculum to determine the organism's ability to ferment glucose, maltose, lactose, sucrose, and fructose within 4 hours. All of the Neisseria species are oxidase positive. It does not differentiate between the various species. The majority of the Neisseria species are catalase positive. A superoxol test utilizing 30% hydrogen peroxide produces weak to strong reactions for the majority of the Neisseria species with only Neisseria elongata being negative. The majority of the Neisseria species are nitrate reduction negative. It is not a useful tool for differentiating the Neisseria species.

A 34-year-old female was seen in the dermatology clinic for some lesions on her fingers that had not responded to topical antimicrobial therapy. A tissue biopsy was sent for histological examination, routine culture, acid-fast bacilli (AFB) culture, and fungal culture. There was no growth on any culture, but AFB were seen in the histological preparations. The tissue culture for AFB had been incubated at both 35oC and 32oC, in liquid media and on media with hemoglobin added for several weeks. What is the most likely diagnosis of her skin lesions? a)Buruli's ulcer b)Swimming pool granuloma c)Leprosy d)AIDS

c)Leprosy Leprosy is the common name for Mycobacterium leprae, which will not grow on artificial media. It is known to infect the skin, mucous membranes, and peripheral nerves. Contrary to historical assumptions, it is not considered highly contagious.

The images show disease presentations associated with Mycobacterium species infections. Which organism correlates to the disease presentation seen in the lower right image? a)Mycobacterium tuberculosis b)Mycobacterium marinum c)Mycobacerium scrofulaceum d)Mycobacterium avium-intracellulare

c)Mycobacerium scrofulaceum The clinical manifestation of Mycobacterium scrofulaceum is scrofula, an enlargement of posterior cervical lymph nodes, as seen in the lower right image. This infection occurs most commonly in young children at the time they are cutting teeth, with commensal organisms in the posterior oropharynx accessing the lymphatic channels with extension to the regional lymph nodes.

Illustrated in the upper image is the anterior portion of a nematode filariform larva with a short buccal cavity. The ovum illustrated in the lower image is also part of the life cycle of this nematode. What presumptive identification can be made from the parasite species listed below? a)Ancylostoma duodenale b)Necator americanus c)Strongyloides stercoralis d)Trichostrongylus spp.

c)Strongyloides stercoralis Strongyloides stercoralis is the correct response. The Strongyloides ovum, as illustrated in the lower image, does not rule out one of the Hookworm species that have similar-appearing ova. However, the short buccal cavity, as illustrated in this upper image, is distinctive for Strongyloides.

The parasitic form represented by this illustration, may be found in the eye and be a cause of keratitis that is associated with contaminated contact lens solution. It measures approximately 25 µm in diameter. What is the likely identity of this parasite? a)Loa loa b)Naegleria fowleri c)Trypanosoma brucei gambiense d)Acanthamoeba species

d)Acanthamoeba species The trophozoites of Acanthamoeba species, such as that pictured, characteristically possess thorn-like pseudopodia (acanthopodia) which serve as a distinguishing feature. Trophozoites of Acanthamoeba species measure 20-45 µm and have a nucleus with a prominent endosome. Both trophozoites and cyst forms may be seen in tissue biopsy

Nitrate reduction is the process by which nitrate is reduced to nitrite; in denitrification, nitrate is completely reduced to nitrogen gas. Which of the following species denitrifies nitrate? a)Yersinia enterocolitica b)Enterobacter cloacae c)Citrobacter amalonaticus d)Pseudomonas stutzeri

d)Pseudomonas stutzeri Most Pseudomonas species, including P. aeruginosa (can be variable) and P. stutzeri, are capable of completely reducing nitrate to nitrogen gas, a process known as denitrification.

This suspicious form was recovered from a stool specimen. What parasite demonstrates this typical morphology? The correct answer is highlighted below a)Brugia microfilaria b)Pseudoparasite c)Taenia solium d)Strongyloides rhabditiform larva

d)Strongyloides rhabditiform larva Strongyloides stercoralis rhabditiform larvae are the only such larvae that are routinely found in stool samples. The rhabditiform larvae are the actively feeding stage. Not as noticeable in the image is the short buccal cavity and prominent genital primordium that is characteristic of Strongyloides. These larvae differ from hookworm larvae because hookworm larvae will have a long buccal cavity and small genital primordium. Hookworm larvae are also rarely found in the stool, and instead, the eggs are more commonly seen.

From the following organisms, which one is considered to be the LEAST pathogenic to humans? A)Corynebacterium ulcerans B)Bacillus anthracis C)Listeria monocytogenes D)Nocardia brasiliensis

A) Corynebacterium ulcerans is correct because this organism is considered a zoonosis and can only occur with close animal contact and human infections are rare. This organism has been linked to causing bovine mastitis.

The tech working on an aerobic wound culture is identifying a colony that is large, gray, and non-hemolytic on blood agar. The tech prepares a Gram stain of the colony and notices a consistency similar to whisked egg whites. Gram stain reveals a large Gram-positive bacillus. What is the most likely identification of this colony? A)Bacillus anthracis B)Bacillus cereus C)Burkholderia mallei D)Francisella tularensis

A) Bacillus anthracis Bacillus anthracis is the most likely identification based on the clues given in this question. B. anthracis is a non-hemolytic colony and has a tenacious consistency, similar to whisked egg whites. The colony morphology can also be called "medusa head" based on the feathery projections that can occur from the margin of the colony. B. anthracis is also a large Gram-positive bacillus that is non-motile and produces endospores. B. anthracis can be present in the wound culture from a cutaneous form of anthrax that causes lesions on the skin.

The addition of Lugol's Iodine to a direct and indirect wet prep is used to detect which of the following protozoan stages? A)Cysts B)Eggs C)Larvae D)Trophozoites

A)Cysts Iodine mounts are helpful to visualize the internal structures of parasites such as protozoan cysts. Protozoans occur as trophozoites and cysts, not as larvae and eggs. Saline mounts help to observe protozoan motility.

Which one of the following adult worms resides in the human intestine? A)Heterophyes heterophyes B)Paragonimus westermani C)Clonorchis sinensis D)Schistosoma haematobium

A)Heterophyes heterophyes Heterophyes heterophyes resides in the human intestine during parasitic infections. Heavy infections cause abdominal pain and discomfort, with chronic mucous diarrhea and eosinophilia. Avoiding undercooked fish and practicing proper fecal disposal are important in preventing and controlling the infection.

This image is of an egg that was found in a stool concentrate, measuring 55 µm. Which of the following parasites does this image represent? A)Trichuris trichiura B)Ascaris lumbricoides C)Echinococcus granulosus D)Enterobius vermicularis

B Ascaris lumbricoides is the correct answer because Ascaris eggs are 45-95 µm x 35-50 µm. The mature eggs of Ascaris lumbricoides vary slightly in their appearance-shape, size, and the presence or absence of an outer albuminous protective coating. This is an example of a mature egg.

An Enterobacteriaceae grows as a clear colony on MacConkey but a salmon-colored colony with a black center on Hektoen enteric agar. Which of the following TSI reactions would match these morphologies? A)Alk/A H2S B)A/A H2S C)Alk/A no H2S D)A/A no H2S

B The Triple Sugar Iron Agar (TSI) contains three sugars; glucose, lactose, and sucrose. MacConkey contains lactose and Hektoen enteric agar contains lactose, sucrose, and an indicator to detect H2S production. From the colony morphologies presented and that the organism was an Enterobacteriaceae, it can be determined that the TSI reaction should demonstrate A/A with H2S. All Enterobacteriaceae ferment glucose resulting *********** of the TSI slant being yellow. The clear colony on MacConkey indicates the organism does not ferment lactose but the salmon-colored colony on Hektoen enteric agar indicates sucrose was ferment resulting in a yellow slant (acid). The black center on Hektoen enteric agar indicates H2S production.

What is the identification and stage of this organism measuring 45 µm that is typically found in stool? A)Balantidium coli cyst B)Ascaris lumbricoides egg C)Schistosoma mansoni egg D)Hymenolepis diminuta egg

B) This image shows a round egg with a distinct corticated outer shell, which is definitive for Ascaris lumbricoides.

Which of the following is the rigid and nonmotile diagnostic stage of amebae that is generally found in a formed stool? The correct answer is highlighted below A)Oocyst B)Cyst C)Trophozoite D)Sporozoite

B) Cyst

Which of the following culture media should be used to attempt to recover mycobacteria from a clinical specimen? A)MacConkey agar B)Lowenstein-Jensen (LJ) medium C)PPLO agar D)Modified Thayer-Martin agar

B)Lowenstein-Jensen (LJ) medium The use of a solid-based medium, such as LJ medium, in combination with a liquid-based medium, is recommended for routine culturing of specimens for the recovery of acid-fast bacilli. Lowenstein-Jensen media is solid-based, and the most commonly used egg-based medium.

Not all strains of Entamoeba histolytica are pathogenic, and recent molecular studies indicated that there is a non-pathogenic variant of Entamoeba histolytica. What is this non-pathogenic variant? A)Entamoeba hartmanni B)Entamoeba moshkovskii C)Entamoeba dispar D)Entamoeba coli

C)Entamoeba dispar Several DNA sequencing assays are available to separate the non-pathogenic variant, Entamoeba dispar, from Entamoeba histolytica. It is important to know that these assays are available in cases where the recovery of an isolate identified as Entamoeba histolytica by conventional methods may not have a clinical correlation.

Illustrated in the upper left image of the composite photograph is a 3-day old colony with a central, granular yellow surface (resembling cinnamon) surrounded by a broad white apron. This colony was recovered from a fungus ball infection of the lung. The microscopic presentation of a methylene-blue stained mount of a sample from the surface of the colony is observed in the upper right and lower left images. The lower right image is a direct mount of the colony showing vegetative hyphae. With these observations, select from the list of multiple-choice responses the correct fungal species as presented. A)Penicillium species B)Aspergillus fumigatus C)Paecilomyces species D)Aspergillus terreus

D Aspergillus terreus is the correct response. Distinctive is the yellow pigmentation of colonies with a granular surface. Observed microscopically is the arrangement of a double rather than a single row of phialides, derived from the surface of a club-shaped vesicle from which straight chains of small, spherical conidia are being produced. Also characteristic of A. terreus is the observation in a direct mount prepared from the colony showing vegetative hyphae with distinctive spherical micro-conidia produced along the outer margins.

This suspicious form, found in a urine concentrate, measures 120 µm by 50 µm. What is the appropriate identification? A)Schistosoma japonicum B)Pseudoparasite C)Trichomonas vaginalis D)Schistosoma haematobium

D) Schistosoma haematobium The only egg typically recovered in urine samples is that of Schistosoma haematobium. This organism as seen in this image is characterized by its distinct shape, particularly the presence of a large terminal spine opposite a rounded end.

Septic arthritis can be caused by Neisseria meningitidis, Streptococcus pyogenes, and Streptobacillus moniliformis. Diagnosing these organisms from joint fluid can be difficult because they may not grow in culture. Which of the following contributes to the cause of non-culturable septic arthritis? A)Antigen/Antibody complexes accumulate in the joint B)T-cells and macrophages invade the joint C)IgE antibodies attach to and activate basophils to the joint D)Antibodies act on red blood cell antigens in the joint

A)Antigen/Antibody complexes accumulate in the joint Antigen/Antibody complexes accumulate in the joint is the correct answer because antigen-antibody complexes form during active infections and the complexes accumulate in the joint causing an inflammatory response that ultimately causes damage to the joint. The complexes accumulate in the joint because they have not been adequately cleared by the macrophages, which causes neutrophils to migrate to the joint. (Type III hypersensitivity)

Which of the following substances may mask parasites in a stool sample? A)Barium B)Saline C)Phosphasoda D)Antimicrobials

A)Barium The presence of barium is known to alter stool specimens so much so that parasites are unrecognizable. If the patient has had a barium enema, the collection of a stool specimen for ova and parasite exam should be delayed for at least 7 days.

A budding yeast with pseudohyphae and clusters of gram-positive staphylococci were observed in a Gram stain smear prepared from a positive blood culture. What is the MOST likely source of the infection? A)Urinary tract B)An indwelling catheter C)Lung abscess D)Subcutaneous cellulitis

B The most likely source of the infection is an indwelling catheter. The budding yeasts with pseudohyphae are indicative of Candida species. The staphylococci seen here are in distinct grape-like clusters, most consistent with S. aureus. Either of these species could account for any one of the clinical conditions indicated in this exercise; however, the most likely common source for both organisms would be an indwelling catheter. Catheters are vulnerable to colonization with organisms found on the patient's skin. Both S. aureus and C. albicans have been recovered as normal skin biota.

Gram stain of a spinal fluid revealed pleomorphic, gram-negative rods. Colonies that appeared on chocolate agar after 24 hours of incubation were gray, opaque, and medium in size. A musty odor was noted when the plate was opened. Gram stain of the colonies on chocolate agar showed small, gram-negative coccobacilli. No growth was seen on sheep blood or MacConkey agar. The next step taken by the technologist to identify this isolate would be to show that the organism: A)Ferments lactose and produces indole B)Decarboxylates lysine C)Requires cysteine D)Requires X and V factors

D) Requires X and V factors Requires X and V factors is the correct answer because the description is typical of Haemophilus influenzae. The best way to identify Haemophilus species is by showing a requirement for X and V factors. Haemophilus species does not ferment lactose, decarboxylate lysine, or require cysteine for growth. Haemophilus species may produce acid from glucose and xylose, but not lactose or sucrose. In addition, Haemophilus species does not grow on sheep blood agar and will give a coccobacilli gram stain morphology.

A CSF specimen is received from a patient with suspected meningitis. Positive Gram stain, along with the results shown here suggest what type of condition? Elevated WBC count Neutrophils predominant Marked protein elevation Marked glucose decrease Lactate level = 37 mg/dL A)Viral meningitis B)CSF leakage C)Multiple sclerosis D)Bacterial meningitis

D)Bacterial meningitis The positive Gram stain, alone, suggests a bacterial infection. The predominance of neutrophils, along with the other abnormal results, point to bacterial meningitis. With viral meningitis, Gram stain does not reveal the presence of bacteria, lymphocytes predominate, and lactate and glucose are normal. CSF leakage would show decreased protein, and multiple sclerosis would show elevated protein, but further tests would be required for diagnosis.

What is the vector for the transmission of Onchocerca volvulus? A)Mosquitoes B)Sandflies C)Reduviid D)Black Flies

D)Black Flies The black fly (Simulium spp.) is the vector that transmits Onchocerca volvulus, a blood nematode, that causes onchocerciasis or "river blindness". This parasite is transmitted during the blood meal by the female fl

What organism with this characteristic morphology that measures 15 µm by 8 µm may be recovered from a stool sample? A)Trichomonas tenax trophozoite B)Enteromonas hominis trophozoite C)Giardia duodenalis trophozoite D)Chilomastix mesnili trophozoite

D)Chilomastix mesnili trophozoite This organism is difficult to distinguish from stool pseudoparasites and artifacts. Fine focusing reveals an irregular oblong organism that comes to a narrow, rounded posterior end (pear-shaped). Keys to the identification of Chilomastix mesnili trophozoites include a spiral groove, when seen; a single nucleus; and a fibril cytostome, which is often difficult to see. The usual size range is 10-15 µm by 4-8 µm.

Which parasite gives birth to live larvae known as microfilariae? A)Strongyloides stercoralis B)Necator americanus C)Diphyllobothrium latum D)Onchocerca volvulus

D)Onchocerca volvulus Helminth parasites that give birth to live larvae do not pass through an egg stage. The larvae mature to adults, multiply, and produce more larvae. Onchocerca volvulus is the correct answer choice and is typically recovered in infected nodules.

Illustrated in the top photograph is a 5-day culture on Sabouraud's dextrose agar obtained from a skin scraping specimen of a "ringworm" lesion from the groin of a 25-year-old male. The appearance of a wine red pigment diffusing into the agar at the margins of a cottony white colony is distinctive. The accompanying microscopic features are observed in the accompanying lactophenol blue-stained mount illustrated in the lower photomicrograph. From the multiple choices, select the species name of the fungal isolate as illustrated. A)Trichophyton rubrum B)Trichophyton mentagrophytes C)Epidermophyton floccosum D)Microsporum gypseum

a) Trichophyton rubrum Trichophyton rubrum is the correct response as the species name and diffuse wine red pigment would indicate. Although the colony morphology is suggestive, the more definitive identification is made by microscopically observing the small, oval-shaped micro-conidia that are directly attached in parallel on either side of thin hyaline hyphae by short, delicate laterally projecting conidiophores. Trichophyton rubrum is an anthropophilic dermatophyte that infects the skin and nails primarily of humans.

The scaling, pink-white appearance of the foot shown in the photograph is characteristic of "Athlete's Foot", a skin infection incurred by athletes after barefoot walks to and from the shower stall. A cottony gray-white fungal colony grew in 5 days from a skin scraping. The identification was made by the microscopic appearance of a mount made from the colony as illustrated in the photomicrograph. From these observations, select the name of this fungal species. The correct answer is highlighted below a)Microsporum gypseum b)Trichophyton tonsurans c)Trichophyton rubrum d)Epidermophyton floccosum

c) Trichophyton rubrum

From the choices listed below, which organism is classified as an aerotolerant anaerobe? The correct answer is highlighted below a)Clostridium novyi b)Staphylococcus aureus c)Lactobacillus species d)Neisseria species

c)Lactobacillus species

Serological detection of the Vi antigen aids in the identification of: A)Escherichia coli B)Klebsiella species C)Salmonella Typhi D)Shigella species

c)Salmonella Typhi Detection of somatic (O), flagellar (H), and capsular (K) antigens are used in the serologic grouping of Enterobacteriaceae. Many members of this family possess somatic and flagellar antigens, whereas non-motile species lack flagellar antigens. From the organism choices, Salmonella Typhi has the capsular Vi (virulence) antigen, which may mask the presence of the O antigen.

Which of the following media would you use to isolate Francisella tularensis: a)Sheep-blood agar b)Lowenstein-Jensen media c)Bordet-Gengou media d)Cystine-heart agar

d)Cystine-heart agar

In the Escherichia coli 0157:H7 serotype. The 0157 portion of the serotype refers to which of the following? A)O somatic antigen B)Vi capsular antigen C)H flagellar protein D)F1 antigen

A)O somatic antigen O somatic antigen is the correct answer because antigen 0157 is found in the lipopolysaccharide layer of the bacteria.

An organism isolated from a sputum specimen and appeared as a dry, wrinkled, off-white colony on sheep blood agar. A Gram stain was performed and Gram positive branching rods were seen. In addition, a modified acid fast was performed and was positive. The organism was later identified as a Norcardia species. Which of the following antibiotics is the appropriate treatment? A)Sulfonamides B)Erythromycin C)Rifampin D)Streptomycin

A)Sulfonamides Sulfonamides is the correct answer. Sulfonamides is a drug of choice in the treatment of Norcadia species infections. Other agents that can be used are amikacin, ceftriaxone, cefotaxime, linezolid, imipenem, and minocyline. The combination of a sulfa-containing agent and one of the primary agents is recommended for serious systemic Norcardia infections.

All of the following are primary routes of transmission for intestinal amoebae, EXCEPT: A)The ingestion of cysts in contaminated food B)The bite of an insect C)The ingestion of cysts in contaminated drink D)Hand-to-mouth contamination

B) BITE The bite of an insect is correct because insect bites are responsible for the spread of hemoflagellates, Plasmodium species, and the filariae.

Illustrated in the top image is the surface of a blood agar culture plate incubated at 35°C for 3 days. Note the growth of tiny smooth, pasty, yellow-white yeast colonies. Although a presumptive identification might be made from the macroscopic morphology, confirmation is made by observing the yeasts forms in the lactophenol stained mount observed in a tease mount prepared from one of the colonies. From these observations, what is the most likely identification? A)Sporothrix schenckii B)Blastomyces dermatitidis C)Histoplasma capsulatum D)Coccidioides immitis

C Histoplasma capsulatum yeast colonies are smooth, white, and glistening. The identification is confirmed by observing microscopically the small 2- 4 µm in diameter yeast cells, often in loose clusters, many of which show a bud connected by a narrow filament. When seen in tissue sections, these budding yeast cells are surrounded by a clear halo appearing as spherical capsules

The 70 µm ovum, illustrated in this high power microscopic view of a saline preparation, is uncommonly found in human feces. This parasite is more commonly found in rats and mice, but infections may be uncommonly transmitted to humans. Water or food contaminated with arthropod related insects within which the cysticercoid larval forms develop may be inadvertently ingested. Once in the human intestine, these larvae develop into adults that attach to the lining cells, and excrete ova that may be observed in fecal specimens. Select the name of the cestode represented by this ovum. A)Taenia solium B)Hymenolepis nana C)Hymenolepis diminuta D)Diphyllobothrium latum

C Hymenolepis diminuta is the correct response. Characteristic of this ovum is its larger size (average 70 µm), spherical shape, smooth thin outer shell, and inner membrane within which are contained three pairs of hooklets. Absent are the pair of polar filaments that extend from either side of the inner hexacanth membrane.

This intestinal parasite was found in a stool specimen and measures 170 µm by 63 µm. What is the most likely identification for this organism? A)Schistosoma japonicum B)Fasciola hepatica C)Schistosoma mansoni D)Ascaris lumbricoides

C Schistosoma mansoni Schistosoma mansoni eggs are yellowish, elongated, have a prominent lateral spine and range in size from 115 to 175 µm x 45 to 75 µm. The size, shape and lateral spine identify the parasite as Schistosoma mansoni. The eggs are typically found in stool.

In which of the following classifications does the helminth Ascaris lumbricoides belong? The correct answer is highlighted below a)Protozoan b)Cestode c)Trematode d)Nematode

d)Nematode

A 55-year-old male immigrant from Korea presented to the ER with severe jaundice. He experienced intermittent but less severe bouts of jaundice in the past. During surgery, his proximal bile duct appeared to be enlarged with a nodular area of inflammation. A surgical biopsy was done and a parasite was observed residing in the lumen in the stained section. Further examination revealed a collection of ova within the ovary of this fluke as see in this image (arrow). Which of the organisms listed below is most likely? A)Clonorchis sinensis B)Fasciola hepatica C)Enterobius vermicularis D)Paragonimus westermani

A) Clonorchis sinensis adult flukes typically occupy the lumen of the biliary ducts within the liver and may on occasion cause intermittent abdominal distress, liver pain, and diarrhea. The identification of this trematode can be suspected in the histopathology section by locating an ovary of the fluke within which the distinctive small (25 µm), urn-shaped ova may be observed, each with a flat shouldered operculum (arrow).

This parasite is typically found in striated muscle and is responsible for which one of the following conditions? A)Trichinosis B)Elephantiasis C)River blindness D)East African sleeping sickness

A) Trichinosis The correct answer is trichinosis. The organism pictured is Trichinella spiralis. This organism is an intestinal-tissue nematode whose larvae encyst by coiling in muscle tissue. Humans are an accidental host that becomes infected when encysted larvae are ingested through poorly cooked pork.

A stool culture from a hospitalized patient produces the following characteristics: Gram-negative bacillusUrease positiveWeakly fermentativeTSI slant is A/A These reactions suggest that the organism is most likely: A)Yersinia enterocolitica B)Escherichia coli C)Plesiomonas shigelloides D)Pasteurella multocida

A) Yersinia enterocolitica Considering the reactions given in this case study, Yersinia enterocolitica would be the best choice. Urease is the key reaction that differentiates these four organisms. Most strains of Plesiomonas shigelloides, Escherichia coli, and Pasteurella multocida are urease negative. Also, Plesiomonas shigelloides demonstrates a K/A reaction on a TSI slant.

The form illustrated in this image is found in stool and measures 45 µm. Please identify the organism: The correct answer is highlighted below A)Balantidium coli cyst B)Ascaris lumbricoides egg C)Fasciolopsis buski egg D)Entamoeba coli cyst

A)Balantidium coli cyst Balantidium coli cyst is the correct answer because of their size of 45 to 55 µm. When visible, the presence of both a macro- and micronucleus as well as cilia around the cyst periphery just inside the cell wall, aid in its identification.

The name of the rapid test seen in the image, often used to differentiate S. pneumoniae from viridans streptococci, in which a drop of 10% deoxycholate was placed on an area of growth, is: A)Bile solubility test B)Bile esculin hydrolysis C)Optochin susceptibility test D)Bacitracin susceptibility test

A)Bile solubility test Bile solubility test is the correct response. The bacterial cells of S. pneumoniae are bile soluble, as shown by the disappearance of the colonies in the area where a drop of 10% deoxycholate had been added to the surface of the agar, as illustrated in the image at the yellow arrow. Lysis depends on the presence of amidase, an autolytic enzyme; bile salts lower the surface tension between the bacterial cell membrane and the media, which enhances the autolytic activity. The colonies of viridans streptococci would remain intact and clearly visible.

Sheep's blood agar is least suitable for the growth of which of the following organisms? A)Haemophilus influenzae B)Staphylococcus aureus C)Streptococcus species D)Neisseria meningitidis

A)Haemophilus influenzae Conventional sheep blood agar is not suitable for the recovery of Haemophilus species. Enzymes in native sheep blood inactivate the V factor, which is required for the growth of Haemophilus species such as Haemophilus influenzae. If the agar medium is supplemented with rabbit or horse blood, Haemophilus species will grow as rabbit or horse blood does not contain these enzymes. Selective Haemophilus isolation media is available: these contain beef heart infusion, peptones, yeast extract (provides V Factor), and defibrinated horse blood (provides X Factor, which is also required for growth of Haemophilus influenza).

This high power image was taken of a saline wet preparation from a stool specimen. The patient, a 45-year-old male with AIDS who recently returned from a vacation to Mexico City, was suffering from recurrent diarrhea. Based on the morphology of the oocyst, select the most probable presumptive identification. A)Giardia duodenalis B)Cystoisospora belli C)Dientamoeba fragilis D)Chilomastix mesnili

B Cystoisospora belli Cystoisospora belli is the correct response. The oocysts of Cystoisospora belli are large, measure up to 30 µm, and have a long oval shape. The oocysts have a thin, smooth outer wall and possess two intra-cytoplasmic sporocysts (immature oocysts may possess only a single sporocyst). In immunocompetent patients, a disease with C. belli is typically self-limiting but is usually more serious in an immunocompromised patient.

The ovum illustrated in this photograph is in an immature stage of development and is surrounded by a residual yolk sack material and membrane. It measures 50 µm in diameter. What is the presumptive identification of this ovum? Please select the single best answer A)Dipylidium caninum B)Taenia species C)Hymenolepis nana D)Diphyllobothrium latum

B Taenia species Taenia species is the intended response. The key distinguishing features are the spherical to oval outline and the distinctive thick shell with radiating striations. At this stage of development, this enclosed immature ovum does not have distinguishing characteristics

The saccharolytic anaerobe that produces red fluorescing colonies when illuminated with a Wood's lamp, as shown in this photograph, is: A)Porphyromonas asaccharolyticus B)Prevotella species C)Bacteroides distasonis D)Fusobacterium nucleatum

B) The production of colonies with black pigment, which also fluoresce red when viewed with a Wood's lamp, are characteristics by which Prevotella species and Porphyromonas species are separated from other anaerobic bacteria, particularly the closely related Bacteroides species. Prevotella species, which produce acids from several sugars (saccharolytic) are separated from Porphyromonas species which are asaccharolytic.

What organism is responsible for a potentially lethal type of food poisoning caused by improperly canned food? A)Bacillus cereus B)Clostridium botulinum C)Clostridium perfringens D)Staphylococcus aureus

B) C. botulinum The correct answer is Clostridium botulinum. Clostridium botulinum causes a potentially lethal type of food poisoning when canned food is improperly canned. According to the Centers for Disease Control and Prevention (CDC), "C. botulinum is an anaerobic, gram-positive, spore-forming rod that produces a potent neurotoxin. The spores are heat-resistant and can survive in foods that are incorrectly or minimally processed." It takes only a small amount of neurotoxin to produce paralysis and death.

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious health concern in the hospital environment and also in the community for patients who have had no contact with the healthcare setting. In order to control the spread of MRSA and prevent infection with the organism, it is recommended to screen patients for MRSA prior to being admitted to a healthcare setting. Which of the following antimicrobials is best to use when testing for methicillin resistance? A)Methicillin B)Cefoxitin C)Penicillin D)Oxacillin

B) Cefoxitin Cefoxitin is the recommended antimicrobial to use for the detection of methicillin resistance in Staphylococcus aureus isolates. Since methicillin is no longer used in the US, resistance has routinely been tested by using oxacillin. However, it is now known that cefoxitin is a better inducer of resistance mediated by the mecA gene - the gene responsible for methicillin resistance in S. aureus.

This suspicious form was seen on a peripheral blood smear. The most likely identification is: The correct answer is highlighted below A)Onchocerca microfilaria B)Plasmodium schizont C)Leishmania amastigote D)Plasmodium gametocyte

B) Plasmodium schizont Plasmodium schizonts are distinct in that they consist of numerous merozoites (the size and arrangement of them vary by species) that when mature may infect previously uninfected red blood cells or develop into macro- and microgametocytes that unite, both routes of which keep the parasite viable.

Which of the following parasites enters the human host through the ingestion of infected pork? A)Schistosoma mansoni B)Trichinella spiralis C)Necator americanus D)Ascaris lumbricoides

B) Trichinella spiralis Trichinella spiralis enters its host through the ingestion of undercooked pork containing encysted larvae. The larvae are released in the intestine and the offspring migrate to muscle tissue to complete the maturation cycle.

Choose the fungi that may be identified to a genus level, when the fungal structures that are seen in this photomicrograph are present in tissue sections. A)Curvularia species B)Aspergillus species C)Penicillium species D)Microsporum canis

B)Aspergillus species Aspergillus species is the correct selection. A suggested genus identification of Aspergillus can be made if distinctive uniform septate hyphae are observed, characterized by dichotomous branching at 45-degree angles.

The tech in microbiology receives a call from the ER where the doctor suspects a patient has inhalation anthrax. What should the tech indicate is a proper specimen for collection to detect inhalation anthrax? A)Sputum B)Blood C)Urine D)Stool

B)Blood The specimen of choice for diagnosis of inhalation anthrax is blood. With inhalation anthrax, the organism will get into the bloodstream. Blood cultures can be taken but will require incubation and waiting for the organism to grow, which can delay diagnosis. Blood can also be taken to look for antigens or antibodies in the blood against anthrax to assist with a diagnosis.

A patient grew out a Staphylococcus lugdunensis and after susceptibility testing, the isolate gave results indicating probable resistance to oxacillin. Which of the following is the best method to detect the mec-A gene to determine if the organism has true oxacillin resistance? A)Oxacillin agar screen B)Cefoxitin disk diffusion C)Vancomycin agar screen D)D-zone test

B)Cefoxitin disk diffusion Cefoxitin disk diffusion is the correct answer because the use of a cefoxitin disk can detect the presence of the mecA gene in Staphylococcus aureus, Staphylococcus lugdunensis, and coagulase negative staphylococcus. For Staphylococcus aureus and Staphylococcus lugdunensis, if zone growth is = 21mm, this indicates mecA positive. If zone growth is = 22mm, the organism is mecA negative. For coagulase negative staphylococci, zone growth = 24 mm indicates mecA positive. Zone growth = 25 mm, the organism is mecA negative.

The term "hydatid sand" is used in reference to which of the following tapeworms? A)Taenia saginata B)Echinococcus species C)Hymenolepis diminuta D)Hymenolepis nana

B)Echinococcus species Echinococcus species eggs, passed by infected animals, are ingested by grazing farm animals or humans and then, localize in different organs, where they develop into hydatid cysts containing many larvae. Echinococcus eggs, when swallowed by humans, produce embryos that penetrate the small intestine, enter the circulation and form cysts in the liver, lung, bones, and sometimes, the brain. The cyst is very slow growing in humans and is generally fluid-filled with a germinal layer from which thousands of scolices bud. The scolices in the hydatid fluid resemble grains of sand and are thus referred to as hydatid sand.

Illustrated in the top photograph is a circumscribed colony after 3 days of incubation at 30o C. The consistency is cottony to wooly and pigment ranges from gray to deep brown. A light pigmented outer apron is seen at the margins of growth. The reverse is dark brown to black, resulting from a darkly pigmented mycelium. As the colony morphology is not species specific, the identification can be made by the appearance of the macroconidia observed in a stained tease mount made from the surface of the colony as observed in the bottom photomicrograph. From these observations, select from the multiple choices the name of this fungus. A)Curvularia species B)Exserohilum species C)Nigrospora species D)Bipolaris species

B)Exserohilum species Exserohilum species is the correct response. The conidia are distinctive in being long and pencil-shaped, with a large number of cells (8 - 10) separated by transverse septa. Of particular note is the extended, prominent protruding extension from the hilar cells, from which the genus name "Exserohilum" is derived.

The reactions in the tubes illustrated in this exercise (reading from left to right: TSI, Pseudosel, OF glucose closed, and OF glucose open) indicate that the bacterial species in question is: A)Glucose fermenter B)Glucose oxidizer C)Lactose fermenter D)Asaccharolytic

B)Glucose oxidizer The lack of yellow conversion of either the slant or the deep of the TSI tube or both indicates that the unknown bacterial species is not a glucose or a lactose fermenter. The conversion of the open tube to a yellow color in comparison to the closed tube which remains green indicates that the bacterial species utilizes glucose oxidatively; therefore, is a glucose oxidizer. The production of a green pigment in the Pseudosel tube identifies this glucose oxidizer as Pseudomonas aeruginosa.

The segmented, dark-staining grains seen in this photomicrograph are most commonly seen in cases of chromoblastomycosis. Which of the fungal species listed below is known to cause this disease? A)Trichophyton schoenleinii B)Phialophora verrucosa C)Sporothrix schenckii D)Epidermophyton floccosum

B)Phialophora verrucosa Of the fungal species listed, only Phialophora verrucosa is associated with chromoblastomycosis and has the capability of producing the grains seen in the photograph. Chromoblastomycosis is a chronic fungal infection of the skin that develops over months to years. It is asymptomatic and commonly found on the lower extremities.

The entire, smooth, transparent colonies surrounded by distinct zones of beta hemolysis, as illustrated in the photograph to the upper left, were recovered after 24 hours of incubation from a vaginal canal swab culture from a 26-year-old mother with signs of premature labor during her 35th week of gestation. Observed in a Gram stain prepared from one of the colonies were Gram-positive cocci that were arranged in chains of 4 to 15 cells (upper right). More characteristic is the arrow-head zone of beta hemolysis observed in the agar CAMP test shown in the lower right image. From these observations, the presumptive identification of this isolate is most likely? A)Streptococcus pyogenes B)Streptococcus agalactiae C)Streptococcus bovis D)Streptococcus pneumoniae

B)Streptococcus agalactiae Streptococcus agalactiae (Group B Streptococcus is the correct response. The colonies observed on the surface of the agar plate are relatively large compared to the surrounding zones of beta hemolysis. The hemolysis is also described as "ground glass" rather than clear. Characteristic is the production of the arrow-shaped zone of beta hemolysis at the junction of the streak marks on the agar CAMP test. The Lancefield antigen test is reactive for Group B. S. agalactiae is commonly recovered from cases of in-utero infections related to pre-mature labor. Para-natal organism transmission during fetal delivery may result in infections of newborns if the bacteria are not detected and removed with antibiotic therapy.

A CSF spinal shunt specimen grew out an Enterococcus species. What parasitic species should be of concern when an Enterococcus species is isolated from a spinal fluid? A)Trichuris trichiura B)Strongyloides stercoralis C)Necator americanus D)Ancylostoma duodenale

B)Strongyloides stercoralis Strongyloides stercoralis is correct. Strongyloides stercoralis is an intestinal parasite that can penetrate the skin and then migrate to the heart and lungs by the circulatory system. From the lungs, it will become swallowed and enter the digestive tract until it matures into an adult worm. In hyper infections, penetration of the intestines by the filariform larvae can damage the bowel, which can lead to septicemia or meningitis. Enterococcus species is a common finding in shunt-associated infections since this organism is part of the human microbiota of the intestines. However, when Enterococcus species is isolated from CSF specimens, this parasite should be under consideration as a contributor to the cause of meningitis.

Illustrated in the top image are 10 day old rough, buff, gray-white colonies growing on Middlebrook 7H11 agar. These colonies are commonly recovered from expectorated or induced sputum specimens obtained from patients with signs and symptoms of pneumonia. The appearance of these colonies provide for a presumptive identification, supported by the positive yellow-pigmented niacin reaction seen in the reagent tube in the lower photograph. From these observations, select from the multiple choices the presumptive identification of this isolate. A)Mycobacterium fortuitum B)Mycobacterium kansasii C)Mycobacterium tuberculosis D)Mycobacterium gordonae

C Mycobacterium tuberculosis requires 10 days or more of incubation for growth. It is characteristically described as a rough, non-pigmented or buff colony. It also produces a rapid positive nitrate test reaction. Reactivation adult tuberculosis is a slowly progressive inflammatory process in the lungs, with intense granulomatous inflammation and cavity formation.

The blue color seen in Simmon's citrate agar slant to the right tube shown in this photograph, indicating a positive reaction, results from: A)Reduction of citric acid to sodium citrate B)Assimilation of carbon from sodium citrate C)Production of ammonia from ammonium phosphate D)Formation of amines from peptones in the medium

C Simmons citrate medium contains inorganic sodium citrate as a source for carbon, and ammonium phosphate, which serves both as a buffer and as a source of nitrogen. Bacterial species that can extract carbon from the sodium citrate can also extract nitrogen from the ammonium phosphate, resulting in the release of ammonia (NH3), causing a rise in pH of the medium and conversion of the bromthymol indicator from green to blue. Although the utilization of carbon from sodium citrate may reduce the amount of acid ions making the medium more alkaline, this pH shift is insufficient to convert the indicator.

A key laboratory characteristic by which Mycobacterium bovis can be separated from Mycobacterium tuberculosis is: A)Niacin accumulation when grown on egg based medium B)Ability to take up iron salts from the culture medium C)Growth inhibition by thiopine-2-carboxylic acid hydrazide (T2H) D)Semi-quantitative catalase

C) Mycobacterium bovis is selectively inhibited by T2H, a key characteristic by which it can be separated from M. tuberculosis.

When a lumbar puncture is performed, what volume of spinal fluid is needed for optimal recovery of meningitis-causing organisms? A)4-5 mL B)1-2 mL C)5-10 mL D)3-5 mL

C) 5-10mL 5-10 mL is the correct answer because this volume of cerebral spinal fluid will allow for optimal recovery of meningitis-causing organisms. In addition, volume is important for detecting certain microorganisms such as mycobacteria and fungi because these organisms are slow-growing and may be difficult to recover in small numbers.

Which of the following fungal infections is endemic in the Southwestern United States desert regions? A)Histoplasmosis B)Blastomycosis C)Coccidioidomycosis D)Sporotrichosis

C) Coccidioidomycosis Coccidioides immitis, the agent of coccidioidomycosis, is found primarily in the desert areas of the southwestern United States. It may also be found in the semiarid areas of Mexico and Central and South America.

This micrograph is most consistent with the cell morphology of: A)Bacillus cereus B)Rothia dentocariosa C)Corynebacterium diphtheriae D)Actinomyces meyeri

C) Corynebacterium diphtheriae The morphology of the "diphtheroids" is sometimes described as resembling Chinese or Oriental letters (also described as palisades: cells lying in parallel rows).

This 30 X 50 µm ovum is most commonly observed by the microscopic examination of transparent adhesive tape mounts of perianal skin from children complaining of nocturnal anal pruritus. What is the most likely presumptive identification? A)Cystoisospora belli B)Necator americanus C)Enterobius vermicularis D)Trichuris trichiura

C) Enterobius vermicularis Enterobius vermicularis is a correct response. The eggs are collected using a sticky paddle or a piece of clear cellophane tape pressed against the perianal region. Enterobius ova are oval in outline with flattening along one margin, simulating a deflated football. The shell is smooth and slightly thickened. A well-developed larva is commonly observed internally, which retracts away from the inner shell membrane, leaving an open space.

The upper image of a blood agar plate illustrates the smooth, gray, nonhemolytic colonies that were recovered after 36 hours incubation from a wound of the forearm of a 14-year-old boy following a dog bite. The colony had a musty or mushroom odor and is oxidase positive. It did not grow on MacConkey agar. The lower image illustrates the gram stain prepared from the colony. The most likely identification is: A)Capnocytophaga canimorsus B)Moraxella catarrhalis C)Pasteurella multocida D)Bordetella bronchiseptica

C) Pasteurella multocida Pasteurella multocida is a small Gram-negative, oxidase positive bacilli frequently associated with bite wounds from canines or felines. The organism grows on sheep blood agar as a smooth, gray, nonhemolytic colony with a musty, mushroom odor. It does not grow on MacConkey agar.

The attached photograph shows a POSITIVE Christiansen's Urea slant four hours after it was inoculated with a Gram-negative rod. Which of the following organisms is the most likely? The correct answer is highlighted below A)Salmonella species B)Escherichia coli C)Proteus mirabilis D)Shigella sonnei

C) Proteus mirabilis Proteus mirabilis is the correct response. Most strains of Proteus species show rapid production of urease. In Christiansen's urea slant, the production of urease is indicated by the pink-red color. The color change is due to the urease produced hydrolyzing the urea in the media to form ammonia which is alkaline resulting in a pH change. The phenol red indicator in the media changes to pink-red in alkaline conditions. This positive reaction often can be demonstrated within a few hours of incubation.

Based on the structures observed in this microscopic image, the most probable identity of the fungus recovered from an induced sputum specimen is: A)Fusarium species B)Penicillium species C)Aspergillus species D)Syncephalastrum species

C)Aspergillus species Shown by the red arrow is a vesicle of Aspergillus species, with the production of irregular chains of conidia from phialides that are hidden. The yellow arrow points to a cleistothecium, the telomorphic form that may be produced in clinical isolates by certain strains. Aspergillus nidulans produces cleistothecia in culture isolates from clinical specimens.

In hookworm infections where progressive anemia is present, what additional test procedure should be performed to determine infection in stool specimens? A)Permanently stained smear B)Modified acid-fast stain C)Concentration technique D)Wet mount preparation

C)Concentration technique The diagnosis of hookworm infection relies on detecting eggs in the patient's stool. There may be few eggs in a sample with light infections, so a concentration technique would be the best procedure for the detection of eggs. The concentration technique removes as much debris as possible, and the sediment is either stained with iodine or left unstained. Increased egg counts of 20/mg or more are associated with symptoms indicative of heavy worm burdens. Egg counts of 5/mg are rarely associated with symptoms.

This ubiquitous parasite is found primarily in areas where sheep and cattle are raised. The natural hosts for the completion of its life cycle are sheep. Humans often serve as accidental hosts. Which of the following conditions may be associated with the presence of this stool parasite 130-150 µm long by 60-90 µm wide? A)Paragonimiasis B)Fasciolopsiasis C)Fascioliasis D)Ascariasis

C)Fascioliasis The disease caused by Fasciola hepatica is called Fascioliasis. The egg shown here resembles that of either Fasciola hepatica or Fasciolopsis buski. The eggs of both flukes are identical and are considered indistinguishable. They both consist of an oblong undeveloped miracidium equipped with a distinct operculum. However, the upper limit of size is considered Fasciola hepatica. Both of these parasites are transmitted through ingestion of raw infected water plants. Additionally, the geographic distribution of Fasciola hepatica is worldwide and the natural host for completion of the life cycle is the sheep. Recovery of the adult flukes is necessary to confirm the identification between the two organisms.

Select the genus/species identification for the ovum (30-47 µm) observed in this high-power image of an unstained saline wet mount. A)Hymenolepis diminuta B)Diphyllobothrium latum C)Hymenolepis nana D)Taenia solium

C)Hymenolepis nana The ovum of Hymenolepis nana has a smooth, thin outer capsule and an inner hexacanth membrane. Within the inner hexacanth membrane is a pair of hooklets. Of most distinction are the pair of polar filaments that extend from either side of the inner membrane.

Norcardia species can be isolated from cutaneous specimens and can produce sulfur granules. These granules can be found in tissue specimens and can aid in detecting aerobic actinomycetes. To help identify the presence of sulfur granules in tissue specimens, which of the following methods will be most beneficial? The correct answer is highlighted below A)Gram stain B)Acid fast stain C)KOH Mount D)Gomori methenamine-Silver (GMS)

C)KOH Mount KOH Mount is the correct answer because this is a rapid test that can detect sulfur granules in tissue. By performing a KOH mount on tissue specimens, proteinaceous material can be digested in order to detect the presence of sulfur granules. Aerobic actinomycetes, such as, Actinomadura species, Nocardia species, and Streptomyces species can grow in tissue as small, hard colonies, which are referred to as sulfur granules.

Infections of the bone marrow are not only caused by bacteria and fungi, they can be caused by viruses as well. Which of the following viruses can often be isolated from bone marrow specimens? A)Varicella-Zoster Virus B)Herpes Simplex Virus C)Parvovirus B19 D)Respiratory Syncytial Virus

C)Parvovirus B19 Parvovirus B19 is the correct answer because viral replication takes place in human cells and is largely restricted to erythroid progenitor cells, adult bone marrow, and fetal liver cells. Parvovirus B19 is also known as fifth disease and can cause aplastic anemia in patients who have hemoglobinopathies and fetal infections by transplacental inoculation.

A flagellar stain would show peritrichous flagella for each of the following organisms except: A)Bordetella bronchiseptica B)Alcaligenes faecalis C)Pseudomonas aeruginosa D)Escherichia coli

C)Pseudomonas aeruginosa Pseudomonas aeruginosa, and other Pseudomonas species, are motile via a single polar flagellum. All of the other motile strains listed possess peritrichous flagella.

A 16-year-old male athlete presented to his physician complaining of a persistent cough, fever, bloody diarrhea, and lethargy. The patient noted that he had recently competed in a freshwater swimming competition in the Caribbean. Physical examination revealed dermatitis on the patient's right calf. A battery of tests was ordered including a CBC, chemistry profile, and a stool specimen for both culture and parasitic examination. The CBC revealed the presence of eosinophilia; other hematology and chemistry tests were unremarkable. The stool culture was negative. A suspicious egg seen here measuring 165 µm by 68 µm with a large lateral spine was seen on the parasite preparations made from the stool sample. This patient is most likely suffering from an infection with: A)Schistosoma japonicum B)Fasciolopsis buskii C)Schistosoma mansoni D)Fasciola hepatica

C)Schistosoma mansoni Schistosoma mansoni is the correct response. This parasite is found in Africa, South America, West Indies, and Puerto Rico. The eggs are elongated and oval in shape. They measure 114-180 µm and have a large lateral spine. Human contraction of the schistosomes occurs following swimming in contaminated fresh water. Infective cercariae, residing in such water, penetrate human skin and establish a residence in select blood vessels of the body.

In the late 1990s, an outbreak of pneumonia was experienced by several high school students involved in a clean-up day held in a Midwestern community. One student experienced a severe disseminated infection. The colony growing on Sabouraud Dextrose with Brain Heart Infusion (SABHI) agar and incubated at 30o C and shown on the top photograph was recovered from an induced sputum specimen. The colony matured in 8 days, presenting a hair-like, cottony surface mycelium. The identification was confirmed by observation of the lactophenol tease mount obtained from the surface of the mycelium. From the list of choices below, select the name of this isolate. The correct answer is highlighted below A)Coccidioides immitis B)Sporothrix schenckii C)Blastomyces dermatitidis D)Histoplasma capsulatum

D Histoplasma capsulatum is the correct response. Although the appearance of the colony is not species-specific, the delayed growth and hair-like, cobweb surface of the mycelium would suggest a dimorphic fungus. The identification of Histoplasma was made microscopically based on the appearance of the 10 - 20 um, circular, roughened, spike-like (tuberculate) macroconidia being borne along delicate hyphae, as illustrated in the image.

When working up a culture, Scedosporium species may presumptively be identified if colonies have a "house mouse" gray appearance and microscopically observed are long delicate condiophores from the tips of which are produced a single oval conidium ("lollipop"). In some cases, further examination of the microscopic mount may reveal the branching, sheath-like arrangement (graphium form) of conidiophores as seen in the top image, and/or the spherical conidia-containing ascospores seen in the lower image. From the multiple choices, indicate the fungal species to be recognized. A)Sepedonium species B)Chrysosporium species C)Scedosporium species D)Pseudoallescheria boydii

Pseudoallescheria boydii Pseudoallescheria boydii is the correct response. As both the "house mouse gray" colonies and portions of the microscopic view of the hyphae and conidia are consistent with Scedosporium species, the added observation of the sheath-like arrangement of conidiophores and the presence of ascospores containing small spherical conidia would indicate Pseudallescheria.