Microbiology Study Set

The fungal colonies illustrated in 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 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. Select from the multiple choices the Aspergillus species represented by these observations.

Aspergillus flavus

Who am I, here in this mush,Looking like a test tube brush?

Erysipelothrix rhusiopathiae

The tubes below are the Hugh and Liefson O/F basal medium with glucose and a pH indicator of bromthymol blue. The image below demonstrates a reaction of:

Glucose non-oxidizer

Several methods of detection are available for the detection of Clostridium difficile in clinical samples. Which methods have the capability for detection in less than 48 hours? (Choose all that apply.) a. Cytotoxicity neutralization assay b. Glutamate dehydrogenase (GDH) antigen assay c. Antigenic detection of toxins A and B d. Polymerase chain reaction (PCR) e. Cultivation on selective media

Glutamate dehydrogenase (GDH) antigen assay Polymerase chain reaction (PCR) (partially correct)

Illustrated in the high power photomicrograph is a large 140 um ovum as it would appear in a stool specimen preparation. The adult flukes reside in the portal veins of the large intestine where ova are discharged into the lumen and into the feces. Low grade diarrhea may be experienced. From the multiple choices select the species of fluke related to this ovum.

Schistosoma mansoni

Which one of the following parasites migrates through the circulation (blood) before maturing in the portal venous system?

Schistosoma mansoni

A gram-negative coccobacillus produces small gray colonies surrounded by a zone of hemolysis on a potato-blood-glycerol agar. The organism also grew on chocolate agar, but NOT on sheep blood agar. This is MOST likely to be which organism?

Bordetella pertussis

A gram-negative coccobacillus produces small gray colonies surrounded by a zone of hemolysis on a potato-blood-glycerol agar. The organism aslo grew on chocolate agar, but NOT on sheep blood agar. This is MOST likely to be which organism?

Bordetella pertussis

The small, slowly growing gray-white colonies seen on the blood agar plate were recovered from a blood culture of a 40-year-old farm worker who developed fever and chills leading to septicemia, following ingestion of contaminated milk. The gram stain of this organism is seen in the lower image revealing small gram-negative coccobacilli in loose clusters. Key to the identification of this blood culture isolate is the rapid urease reaction. From these observations, select from the multiple choice the presumptive identification of this isolate.

Brucella species

Spinal fluid cultures on a 3-day-old infant revealed beta-hemolytic, Gram-positive cocci occurring in pairs and chains. The organism was catalase-negative and bile esculin-negative. Resistance to 0.04 U disk of bacitracin was noted. The other test necessary to identify this organism is a positive test by:

CAMP

A definitive diagnosis of malaria can be made by:

Demonstration of the organisms in peripheral blood

Infectious disease processes in which large numbers of activated macrophages and histiocytes are collected at the site of inflammation is called:

Granulomatous

Illustrated in the upper image is a 4 day growth of a fungus colony on Sabouraud's Dextrose agar. Note the cottony to wooly surface, and the distinctive lavender, pink pigmentation. The lower image is of a lactophenol blue pigmented view of long, narrow multi-celled macro-conidia that are sickle shaped. Based on these observations, select from the multiple choices the genus identification of this isolate.

Fusarium

Which one of the following organisms is sensitive to bacitracin:

Group A Streptococcus

The biochemical testing results of an alpha-hemolytic streptococcus show that the isolate is bile esculin-positive, but does not grow in the presence of 6.5% NaCl. The MOST probable identity of this isolate is what?

Group D streptococcus, non-enterococcus

A 30 year old man with chronic persistent hepatitis developed an abscess in the right hepatic lobe. A needle aspiration revealed purulent material. The small colonies shown in the upper photograph were isolated after 36 hours incubation at 35 degrees C. They emitted a butter scotch odor. The lower photomicrograph reveals the gram stain features. The antigen most likely carried by this isolate is:

Group F

Which one of the following descriptions about Pasturella is FALSE? Select one: a. Forms large amounts of indole. b. Grows well on MacConkey agar. c. Many infections caused by domesticated animals. d. Multocida is species most frequently isolated from humans. e. Produces an odor similar to E. coli.

Grows well on MacConkey agar.

Look, oh look at the little red dot, Tell me, oh tell me, who I am not.

Haemophilus influenzae

Illustrated in this photograph is an H & E-stained section of a gastric biopsy obtained from a patient with suspected peptic ulcer disease. Based on the biopsy findings, the bacterial species that would be most likely to be recovered is:

Helicobacter pylori

What two glycoproteins are expressed on the surface of influenza A viruses and are used for subtyping of the viruses? Select one: a. Hemagglutinin b. Glycoprotein120 (gp120) c. Glycoprotein41 (gp41) d. Neuraminidase

Hemagglutinin Neuraminidase

Match the viruses below with their associated diseases

Hepadnavirus - Hepatitis Arbovirus - Encephalitis Parvovirus - Fifth disease Paramyxovirus - Measles-Mumps

Illustrated in this photograph is a sulfide indole motility (SIM) tube (left) and an esculin hydrolysis slant (right) after inoculation with an unknown gram positive bacillus and incubation at 30 degrees C for 24 hours. Based on the reactions observed, the most likely identification is:

Listeria monocytogenes

The CAMP reaction is most helpful in the identification of n=beta hemolytic streptococci, group B (shown in the photograph as the arrowhead-shaped zone of the hemolysis at the tip of the red arrow). A beta hemolytic gram positive bacillus that produces the rectangular-shaped area of hemolysis as shown by the blue arrow in the photograph is:

Listeria monocytogenes

Which bacterial species is a common agent of neonatal bacteremia?

Listeria monocytogenes

What is the primary target of the Hepatitis B virus?

Liver

Which of the following species of Mycobacteriummight be associated with contamination of the hot water system in large institutions such as hospitals?

M. xenopi

Any laboratory that analyzes microbes or refers specimens that have the potential to contain microbial agents or toxins is a sentinel laboratory.

True

In molecular diagnostic testing, hybridization employs complementary base pair binding of a synthetic strand to DNA or RNA

True

The bacterial species illustrated in these photographs was recovered from septic peritoneal fluid of a patient undergoing continuous peritoneal dialysis. The most likely identification is:

Micrococcus luteus

Illustrated are photomicrographs prepared from histological sections of a duodenal biopsy obtained from a patient with AIDS who was experiencing chronic diarrhea. Tiny intra-cytoplasmic spores are observed in both the left hand PAS stained and on the right Methylene blue-stained sections. The spores are best visualized in the PAS-stained section on the left (arrow). Stool specimens had been negative for parasites or bacterial pathogens. The acid-fast is negative with a positive Weber stain (Chromotrope 3R. Fast Green, phosphotungistic acid) confirming an identification. From the list of multiple choices, select the most probable presumptive identification.

Microsporidium species

Under a Woods' lamp, infected hair strands from several children with tinea capitis showed green fluorescence, and subsequent cultures grew fungi with aerial mycelia and terminal chlamydospores. These isolates are most likely:

Microsporum audouinii

Each of the following tests is helpful in the species identification of Staphylococcus aureus except: Select one: a. Thermostable endonuclease b. Deoxyribonuclease c. Modified dimethyl sulfoxide (DMSO) test d. Tube coagulase test

Modified dimethyl sulfoxide (DMSO) test

Surprise. The purulent exudate the intracellular bacteria (shown by the arrows) as illustrated in this photomicrograph was observed in a direct sputum Gram stain of a 70 year-old patient with chronic obstructive pulmonary disease. The bacterial species that most likely grew out in culture is:

Moraxella catarrhalis

Look, look, can you not see What penicillin has done to me?

Moraxella osloensis

The colonies shown in this 5% sheep blood agar (left) and MacConkey agar (right) split frame photograph are most likely those of:

Morganella morganii

Illustrated in these paired photomicrographs are acid fast stains of tissue sections of colon obtained from an AIDS patient with chronic diarrhea, illustrating a heavy infiltration with acid-fast bacilli (upper image), literally engorging the submucous macrophages (lower image). The Mycobacterium species most commonly associated with this infection is:

Mycobacterium avium intracellulare complex

The Mycobacterium species capable of growing on modified MacConkey agar (crystal violet removed from the formula), as illustrated in this photograph, is:

Mycobacterium fortuitum

The red ring at the top of the media in this tube indicates a positive indole reaction. The precursor substance in the medium from which the indole is produced is:

Tryptophan

Which of the following specimens is the most sensitive for detecting active CMV infection:

Urine

Select from the following choices the specimen that is inadequate for the recovery of anaerobes and should be summarily rejected upon receipt in the microbiology laboratory. Select one: Swab specimens taken from a deep sub-cutaneous abcess Needle aspirate in an anaerobic E-swab tube Syringe aspirate hand-carried to microbiology laboratory Uterine cervical swab in Cary-Blair transport medium

Uterine cervical swab in Cary-Blair transport medium

The end product of the fermentative metabolism that characterizes members of the Enterobacteriaceae is:

Various mixed acids

Illustrated in the photograph is what appears to be a tapeworm strobili in which the individual proglottids appear broader than long. If this segment was observed in a stool specimen, select from the multiple choices the presumptive identification.

Vegetable artifact

A cerebrospinal (CSF) cell count is 1000 cells/µL. The cells on differential are predominantly lymphocytes. CSF protein is moderately elevated and the glucose is normal. No microorganisms were observed on a Gram's stain smear of the CSF sediment. What is the MOST likely condition?

Viral meningitis

Which of the following assays is routinely used for confirmation of HIV infections:

Western blot

In order to speciate a swarming Proteus organism found on an eosin methylene blue agar plate, the BEST approach would be to:

determine Indole production, phenylalanine and urease activity

The skin infection of the foot of a farmer as illustrated in the upper photograph was caused in a farmer when walking barefoot in soil contaminated with a filariform larva. Based on the morphology of the 50 um in diameter ovum (lower image), select from the question/answer list the species that is the presumptive cause of the infection.

Necator americanus

The Quellung test is useful for which of the following:

Serological typing of Streptococcus pneumoniae

This isolate is a catalase negative, gram positive coccus on sheep blood agar. The P disk has 5 ug of optochin and the zone around it is 16 mm. It has been streaked perpendicular to a beta lysine-producing Staphylococcus aureus. The presumptive identification is:

Streptococcus pneumoniae

Bacitracin susceptibility is useful for which two of the following: Select one or more: a. Distinguishing Staphylococci from micrococci b. Presumptive identification of Group A streptococci c. Identification of Haemophilus d. Identification of Neisseria

a. Distinguishing Staphylococci from micrococci b. Presumptive identification of Group A streptococci

The sequence of nucleic acid in a variety of viruses and viral host, will find more similarities

between viruses and their hosts than among different viruses

Which of the following two media are appropriate for Bordetella pertussis: Select one or more: a. Thayer-Martin media b. Lowenstein-Jensen media c. Bordet-Gengou media d. Regan-Lowe charcoal agar

c. Bordet-Gengou media d. Regan-Lowe charcoal agar

In tissues infected with Histoplasma capsulatum, which of the following is usually true? Select one: a. hyphae usually invade blood vessels b. encapsulated yeast cells are typical c. conidiophores with metulae and phialides are typical d. fungus is usually intracellular

fungus is usually intracellular

Compared to blood agar media, chocolate blood agar FAVORS the growth of which organisms?

more fastidious bacteria

Which virus is the MOST common etiological agent of viral respiratory diseases in infants and children?

respiratory syncytial virus

An acid-fast bacillus is isolated and produces an orange pigment when grown in either the light or the dark. Which type of organism has most likely been isolated?

scotochromogen

The isolate is represented by the slow growing small, gray-white, opaque and non-hemolytic colonies on blood agar. Short, gram-negative bacilli are, lying singly but also in the form of characteristic "rosette-like" clusters (arrows) are observed in the lower photomicrograph. As additional biochemical reactions necessary to confirm a presumptive identification, oxidase and indole reactions are positive; catalase, nitrate and urease reactions are negative. Based on these observations, select from the multiple choices the presumptive identification of this isolate.

Cardiobacterium hominis

Match each virus with its appropriate nucleic acid content.

RNA - Paramyxovirus RNA - Rhabdovirus DNA - Poxvirus RNA - Orthomyxovirus

HIV is known as a retrovirus because:

RNA is used as the template for DNA synthesis

Illustrated in the image shown is the fruiting head of one of the fungal agents of chromomycosis. Note the small clusters and short chains of elliptical conidia produced from the tips of branching conidiophores. Which of the following choices represents the type of sporulation illustrated in this image?

Acrotheca sporulation

The entire, smooth, golden yellow-pigmented non-hemolytic colonies on the surface of the blood agar plate seen in the upper image have been recovered in hospital acquired infections from patients with cystic fibrosis. A Gram stain prepared from one of the colonies as shown in the lower image, reveal long, narrow gram-negative bacilli arranged singly. Polar flagella would be seen in flagellar stains. All carbohydrate reactions are negative except for the oxidative utilization of maltose. Positive biochemical reactions for DNA'se and for esculin assist in making a definitive identification. Based on these observations, select from the multiple choices the identification of this isolate.

(One of these three) Stenotrophomonas maltophilia Flavobacterium meningosepticum Bordetella bronchiseptica

Which of the following would be the most appropriate temperature for long term storage of viral cultures:

-70° C

The fungus illustrated in this photomicrograph was recovered from an induced sputum specimen from a 74 year old man with chronic obstructive pulmonary disease. This isolate is most likely:

A contaminant

The dark brown, wooly to velvety surface of the colony shown in this image suggests one of the dermatiaceous fungi. What additional feature would suggest recovery of one of the agents of chromomycosis, rather than one of the phaeohyphomycetes?

A delay in growth beyond five day

Which of the following are useful serological tests to document antecedent Streptococcal infections: Select one or more: ASO anti-DNAse M-antigen Hemolysin

ASO and anti-DNAse

Which of the following test(s) that are the most useful in separating Listeria monocytogenes from Erysipelothrix rhusiopathiae? Room temperature motility Catalase Esculin hydrolysis

All of the above options

A major difference between Salmonella enterica and Shigella infections is that ONLY in salmonellosis can which of the following be observed? Select one: a. Animals serve as a reservoir of infection. b. Diarrhea becomes the major symptom. c. Endotoxin plays a role in the disease process. d. Exotoxin produces profuse, watery stools.

Animals serve as a reservoir of infection.

The presence of hyaline, septate hyphae, and a young conidiophore with a foot cell and a swollen vesicle in a fungus culture are excellent clues indicative of:

Aspergillus

Based on the structures observed in this photomicrograph, the most probable species of the fungus recovered from an induced sputum specimen is:

Aspergillus nidulans

Illustrated in the composite image on the left is a 72-hour growth on Sabouraud's dextrose agar of a finely granular, black pigmented colony obtained from a subcutaneous abscess at the site of an intravenous transfusion. The image to the right illustrates the microscopic appearance of a small inoculum taken from the surface of the center portion of the colony. A small spherical vesicle is surrounded by a row of phialides producing small, black-staining conidia. With these observations, select from the multiple choices the name of the fungus presented.

Aspergillus niger

Illustrated in the upper left image of the composite photograph is 3 day old colony with a central, granular yellow surface 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. In the lower right image taken of a dig-mount of the colony showing vegetative hyphae. With these observations, select from the list of multiple choice responses the fungal species as presented.

Aspergillus terreus

The photomicrograph shows a close-in view of erythrocytes three of which are infiltrated by what appear to be ring like malarial trophozoites. More mature ones are arranged as doublets. The smear was obtained from a 40-year-old forester working in Connecticut who was complaining of malaise and fatigue. The infected erythrocytes are not enlarged and are normo-chromic. From these observations, select from the multiple choices the presumptive identification of the etiologic agent.

Babesia microti

The lecithin hydrolysis, indicated by the tips of the arrows in this photograph of an egg yolk agar plate, may be produced by each of the following Bacillus species except:

Bacillus subtilis

Which of the following is a presumptive test for the identification of Lancefield group A Streptococcus:

Bacitracin susceptibility

Cultures from past-abdominal cellulitis grow gram negative pleomorphic rods with the following characteristics: Grows on KV agar but does not show fluorescence Produced black colonies BBE agar Resistant to penicillin Which of the following is the MOST likely identification?

Bacteroides fragilis

An abdominal wound culture grows E. coli on the aerobic culture. The anaerobic culture has growth of two gram negative rods, one of which is aerobic. The other gram negative rod has 2+ growth on BBE plate and is resistant to Kanamycin, Colistin, and Vancomycin disc. This organism can be identified as:

Bacteroides fragilis group

The trophozoite illustrated in the photograph is large, measuring 120 um, representative of what might be observed in a stool specimen obtained from an immune-compromised patient with low-grade diarrhea. Select from the multiple choice responses to derive a presumptive identification.

Balantidium coli

A beta-hemolytic Streptococcus was isolated from a throat culture. It gave the following biochemical reactions:· Bacitracin - Susceptible· Bile esculin - Negative· 6.5% NaCl - No growth· CAMP - Negative· SXT - Resistant What is the presumptive identification?

Beta Streptococcus, group A

Illustrated in the photomicrograph is the tail portion of an adult worm of a filarial nematode as it may be observed in a peripheral blood smear. These worms measure up to 300 um in length and commonly inhabit the lymphatics. This nematode species more commonly inhabit the lymphatics. This nematode species more commonly involves the lymphatics of the inguinal region resulting in swelling below the knee in what is known as "elephantiasis". The species indicated in this exercise can be presumptively determined by the orientation of the nuclei within the tail section (arrows). From the nematode species listed below, indicate the most likely species identification.

Brugia malayi

Surprise! Animals are not the only creatures with bacteria. The bacterial species causing onion rot is:

Burkholderia cepacia

A small, microaerophilic, curved, gram-negative rod which was isolated from a diarrhea stool specimen gave the following results:Grew best at 42 ˚C Oxidase positive Resistant to cephalosporin Susceptible to nalidixic acid Hippurate hydrolysis positive What is the MOST probable identification of this organism?

Campylobacter jejuni

I smear the streak line through And grow best at forty two.

Campylobacter jejuni

Illustrated in the top photograph are small, smooth, 48 hour old white yeast colonies growing on potato dextrose agar. The rudimentary spikes from the surface of the colonies (arrows) indicate that a germ tube test should be performed. The bottom image is the germ tube test for this isolate. Select from the multiple choices the identification of this yeast isolate

Candida albicans

Illustrated in the top photograph are smooth white yeast colonies growing on Sabouraud's heart infusion agar (SABHI agar) after 48 48 hours incubation at 30˚ C. The colonies were recovered from a post-operative wound infection in a 65 year old man following an organ transplant. The bottom photograph is representative of more mature colonies after an additional 24 hour incubation. From these observations, select the presumptive identification of this yeast isolate.

Candida albicans

This photomicrograph was prepared from tease mounts of 3 day-old smooth, white yeast colonies obtained from an aspirate of nasal fluid of a middle aged patient with sinusitis. Note the clusters of small blastoconidia along the pseudohyphae and also the larger spherical chlamydospores (arrow), as observed in the right lower corner. From the multiple choices, select the identification of this yeast isolate.

Candida albicans

The media used to isolate Legionella pneumophilia should contain which of the following additives?

Charcoal and yeast extract

In the photgraph to the left is shown a 4 day old colony grown on Sabouraud's Dextrose agar. It was recovered from what was considered a "contaminant" from a bacterial culture. The image to the right was is a high power photomicrograph of a methylene-blue stained mount prepared from the surfaces of the colony. With these observations, select the fungus genus from the multiple choices as listed.

Chrysosporium (best guess)

Except for its two day rapid growth on SABHI agar incubated at 30° C, the hair-like gray-white colony illustrated in the top photograph, consistent with a Zygomycete, was recovered in culture as an environmental contaminant of a skin ulcer. The species identification can be made from the lactophenol blue stained microscopic mount seen in the bottom photomicrograph. From these observations, select from the multiple choices the name of this isolate.

Circinella species

The flat, spreading gray-white colonies with an outer zone of beta hemolysis as observed on the surface of an anaerobic blood agar plate (upper photograph) were recovered from a blood culture of an elderly man leading to a potential diagnosis of cancer of the colon. Observed in the gram stain are short gram-positive bacilli, some with distinctive central and sub-terminal spores. From these observations, select from the multiple choices the name of this isolate.

Clostridium septicum

Although care should be taken when working with all fungus cultures in the laboratory, personnel are particularly prone to develop laboratory acquired infections from the inhalation of airborne species of:

Coccidioides immitis

The growth of the colonies shown in the upper image was obtained on blood agar from a sputum specimen after 8 days of incubation at 30˚ C. The lower image is a photomicrograph of a lactophenol blue mount made from a portion of the colony. The diagnosis is:

Coccidioidomycosis

Which of the following fungal infections is endemic in the southwestern US desert regions?

Coccidioidomycosis

The Chinese transcription shown here is most consistent with the cell morphology of:

Corynebacterium diphtheriae

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?

Costridium difficile

The India ink preparation is used as a presumptive test for the presence of which organism?

Cryptococcus neoformans in CSF

The light gray-white, border to border colony extension when covered in clinical specimen is usually considered as a Zygomycetecontaminant. In this exercise the recovery of this fungus may have been involved as a commensal in both skin and internal infections of patients with immune deficiency or who may have received recent chemotherapy or are post-surgery. The identification can be made by observing the fruiting bodies in the lactophenol blue mount illustrated in the photomicrograph to the right. From these observations, select from the multiple choice selections the name of this isolate.

Cunninghamella species

Which of the following tests would be used to directly document the presence of a specific organism in a clinical specimen:

Direct fluorescent antibody test

Enterobacter cloacae colonies were isolated from a blood culture taken from a 45-year-old woman undergoing chemotherapy for breast cancer. Observe this Kirby-Bauer susceptibility plate and the result report form for this organism. From the multiple choices, identify the resistance mechanism (if any) that this organism demonstrates.

ESBL - Extended-Spectrum Beta Lactamase with chromosomal AmpC

Which one of the following in the INCORRECT match between organism and the appropriate diagnostic procedure? Select one: Trichinella spiralis - serologic testing Cryptosporidium - modified acid-fast stain Echinococcus granulosus - routine ova and parasite examination Schistosoma haematobium - examination of urine sediment Mycobacterium tuberculosis - acid fast stain

Echinococcus granulosus - routine ova and parasite examination

Illustrated in the trichrome-stained mount of a stool specimen, submitted to rule out a parasitic infection, are small 8 - 10 um amoebic cysts. Note the owl-eye nuclei beneath the outer membrane. From this high power microscopic view, select a presumptive identification from the multiple choice selections.

Endolimax nana

Observed in a stool specimen passed from a person with minor intestinal symptoms is an 8 um in diameter cyst as shown in the photomicrograph. Note the four nuclei and their distinctive blotlike karyosomes. Based on the microscopic appearance of this cyst, select from the list of answer choices the presumptive identification.

Endolimax nana

I reside in the mouth where I measure approximately 17 micro meters.

Entamoeba gingivalis trophozoite

What is the probable identity of an organism isolated from a wound culture that demonstrates the following test results? Phenylalanin Deaminase = negative TSI - A/A gas Citrate = positive Lysine = positive SIM = negative/negative/negative Urea = weakly positive

Enterobacter aerogenes

An alpha-hemolytic streptococcus isolated from a wound is resistant to optochin and bacitracin, grows in 6.5% NaCl broth, and is PYR positive. The organism is MOST likely a streptococcus belonging to;

Enterococcus (best guess)

As a gram positive coccus, I've become a bit fancy Short chains and motile, plus I carry the gene VanC.

Enterococcus cassilflavus

Illustrated in the photograph is a bile esculin agar plate inoculated with a bacterial isolate from a urinary tract infection. The most likely identification is:

Enterococcus faecalis

Match the viruses below with their associated diseases.

Epstein-Barr - Infectious mononeucleosis Varicella-Zoster - Chicken pox Rhabdovirus - Rabies Picornavirus - Polio

Which one of the following viruses requires a complex lymphoblastoid cell culture, and is rarely if ever diagnosed by culture:

Epstein-Barr Virus

A patient with atypical (reactive) lymphocytes in his peripheral blood smear should be tested for

Epstein-Barr virus infection

Which two of the following organisms are gram-positive? Pasteurella Erysipelothrix Aeromonas Lactococcus

Erysipelothrix Lactococcus

Among the gram-positive bacilli, the unique species producing H2S as seen in the Kligler Iron Agar slant illustrated in this photograph is:

Erysipelothrix rhusiopathiae

Which of the following dematiaceous fungal species produce conidia in clusters?

Exophiala species

The long, pencil-shaped, multi-celled, thin, and smooth-walled macroconidia illustrated in this image are characteristic of which species?

Exserohilum species

Human papillomavirus (HPV) is a rare infection that always results in a malignant cancer.

False

Minimum inhibitory concentration (MIC) susceptibility tests should be performed against other beta lactam antibiotics on important S. pneumonia isolates from blood cultures and other sterile body fluids when a MIC for penicillin is performed.

False

The age groups that have been most affected by the H1N1 virus are children and younger adults.

False

There is an effective vaccine available on the market to develop HIV specific immunity.

False

Illustrated in the close-in high power microscopic view is a large spherical ovum measuring 130 um as it may appear in a mount of fecal material. These ova often have a brown staining that suggests passage through a biliary duct on its way through the large intestine. Identifying characteristics include a thin, smooth shell and an indistinct, flat, non-shouldered operculum (blue lines). From the appearance of this ovum, select from the multiple choices the presumptive identification.

Fasciola hepatica

Each of the following characteristics will differentiate between Listeria monocytogenes and Erysipelothrix rhusiopathiaeexcept: Select one: a. Hydrolsis of esculin b. Motility c. Catalase d. Fermentation of glucose

Fermentation of glucose

The well circumscribed cutaneous papule with the distinct outer erythematous border illustrated in the upper photograph developed over a period of 5 days at the site of a tick bite. The lower photograph illustrates colonies growing on a buffered charcoal yeast extract agar plate that had been inoculated with material from the ulcer bed three days before. Tiny, pale-staining gram negative coccobacilli were seen on a gram stain. The most likely causative agent is:

Francisella tularensis

The image illustrates a Gram stain of a vaginal smear obtained from an 11-year-old girl suspected of being a victim of sexual abuse. The appearance of intracellular gram-negative diplococci (GNDC), as seen in the segmented neutrophil at the tip of the arrow, can represent different organisms. Therefore, recovery of th eacterial species in culture and biochemical identifications is needed before the case can be resolved. Each of the following may appear as intracellular GNDC EXCEPT for which organism? Neisseria gonorrhoeae Moraxella osloensis Acinetobacter baumannii Gardnerella vaginalis

Gardnerella vaginalis

Illustrated in the top photograph is a 4 day old white to cream-colored colony with a yeast-like background, but with the surface having a delicate silk-like consistency. Such colonies may be recovered as a contaminant in laboratory cultures. The identification is illustrated in a cornmeal agar mount shown in the bottom photomicrograph. From these observations, select from the multiple choices the identification of this yeast-like isolate.

Geotrichum candidum

Match the viruses below with their associated conditions.

Herpesvirus - Herpes Papovirus - Warts Rhinovirus - Common Cold Rotavirus - Gastroenteritis in infants

The mechanism by which certain strains of Enterococcusspecies have developed resistance to the synergistic combination of aminoglycoside and beta-lactam antibiotics is:

High level gentamicin resistance

The colonies shown in the upper image were obtained on blood agar from a sputum specimen after 10 days incubation at 30° C. The lower image is a photomicrograph of a lactophenol blue mount made from a portion of the colony.The delicate cob-web appearance of the colonies on blood agar (upper image) and the production of macroconidia with a conspicuous prickly surface as seen in the lower image are characteristic of:

Histoplasma capsulatum

The most common rapid slide test (MONOSPOT©) for infectious mononucleosis employs:

Horse erythrocytes

In the upper photograph is seen a segment of large bowel to include a short, thin, thread-like adult worm. In the lower photograph is show the scolex of this worm, with a protruding armed scolex and a row of hooklets. Also known as the "dwarf tapeworm", this cestode more commonly causes intestinal infections in children. Select the presumptive identification of this ovum from the choices shown below.

Hymenolepis nana

Which one of the following statements is true regarding the 2009 H1N1 virus?

In 2009, the novel H1N1 virus spread during warmer months

The combination of organisms that is correctly paired with the reactions for appropriate quality control (one organism positive for the reaction and one organism negative for the reaction) are: a. Coagulase: Staphylococcus saprophyticus and Staphylococcus epidermidis b. H2S production: Proteus mirabilis and Salmonella c. Phenylalanine deamination: Escherichia coli and Yersinia enterocolytica d. Indole: Escherichia coli and Proteus mirabilis

Indole: Escherichia coli and Proteus mirabilis

Which enzyme is responsible for joining the reverse-transcribed HIV DNA to the host cell's DNA?

Integrase (best guess)

A 20-year-old female was admitted into the hospital complaining of 10 to 15 bloody mucous stools per day, fever, gastrointestinal disturbances, abdominal pain, and nausea. The preliminary O & P report went out as "Probable Entamoena histolytica trophozoites and cysts, confirmations pending." What is the patient most likely suffering from?

Intestinal amebiasis

I measure 12 micro meters and am found in stool.

Iodamoeba butschlii cyst

Which substance acts as a mordant in the Gram Stain process?

Iodine

Which one of the following comments about Francisella is not true? Select one: a. Can penetrate minute skin breaks b. Causes Tularemia c. Possesses a thin capsule d. Is a strict anaerobe e. Transmitted by tick bites

Is a strict anaerobe

The high power photograph was taken from a saline wet preparation of 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 from the multiple choices the most probable presumptive identification.

Isospora belli

A 65 y/o male with type 2 diabetes presented to ED complaining of febrile episodes following his last dialysis treatment. The microscopic examination of his urine showed numerous white blood cells and bacteria. His urine was sent to the lab for culture and sensitivity. Urine colony count was >100,000 CFU/mL for a single organism that was identified as Klebsiella pneumoniae. Observe the reactions of this organism on the Kirby Bauer antibiotic susceptibility plate and review the susceptibility results on the AST report form. The Hodge Test was positive. Select from the multiple choices the resistance mechanism that this organism demonstrates.

KPC - Klebsiella pneumoniae Carbapenemase

An 87-year old patient had a foot wound that grew gram-negative rods on MacConkey agar as pink to dark pink oxidase-negative colonies along with the following results: TSI: A/A Indole: neg. MR: neg. VP: pos. Citrate: pos. H2S: neg. Urea: pos. Motility: neg. Ornithine: neg. susceptibility: Carboxicillin and ampicillin resistant, all others sensitive. What is the MOST likely organism?

Klebsiella pneumonia

A 30 year old Hispanic pregnant female developed fever and signs and symptoms of meningitis following ingestion of feta cheese sent by relatives in Mexico. The colonies recovered from a positive blood culture is shown in the upper photograph; the microscopic features in the lower photograph. The most likely identification is:

Listeria monocytogenes

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 identification. This species is most commonly recovered from respiratory specimens of patients with pneumonia. Observing 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 in this exercise.

Klebsiella pneumonia

This member of the Enterobacteriacea gave these reactions: TSIA . . . . . . . . . . . . . A/A, gas (+), no H2S Ornithine . . . . . . . . . Negative Lysine . . . . . . . . . . . . Positive Citrate . . . . . . . . . . . . Positive Urea . . . . . . . . . . . . . . Positive Phenylalanine . . . . . . Negative Motility . . . . . . . . . . . . Negative The organism is identified as:

Klebsiella pneumoniae

If CFS tubes numbered #1, #2, and #3 CANNOT be analyzed within one hour, the correct procedure for the microbiology sample tubes is to:

Leave it at room temperature

The entire, smooth, convex Mycobacterium species colonies growing on 7H10 agar were observed to be dark yellow pigmented early in culture even before having been exposed to light. This isolate was found to be Tween-80 positive as seen in the reaction tubes in the bottom photograph. Select from the multiple choices the presumptive identification of this isolate.

Mycobacterium gordonae

Illustrated in this exercise are colonies growing on Middlebrook 7H10 agar before (lower) and after (upper) exposure to light. Colonies are intermediate between smooth and rough depending on the strain. Prior to exposure to light the colonies are gray white. Upon exposure to ambient light, visible yellow pigment production is observed characteristic of one of the "photochromogens", as illustrated in the top composite colony photograph, The acid-fast stain reveals slender acid fast bacilli with cross banding. Characteristic for the presumptive identification of this isolate are positive reactions for several biochemical reactions - nitrate reduction, Tween 80 hydrolysis, catalase, urease and pyrazinamidase. With these observations, select from the multiple choices the species name of this isolate.

Mycobacterium kansasii

Illustrated in this photograph are two Middlebrook 7H-11 plates incubated at 35 degrees C, on which are growing colonies of an unknown Mycobacterium species. The plate on the left was incubated in the dark; the plate at the right had been exposed to light for 24 hours. The most likely identification is:

Mycobacterium kansasii

Which organism is a cell wall deficient bacterium that commonly causes atypical or "walking pneumonia?"

Mycoplasma pneumonia

The bacterial species shown in this composite photograph of a chocolate agar plate and accompanying gram stain, recovered from an autopsy blood culture of a patient dying with Waterhouse Friderichsen syndrome is most likely:

Neisseria meningitidis

As one of the aerobic actinomycetes, the light yellow, entire, convex, smooth, non hemolytic colonies are observed on blood agar. The gram stain, showing gram-positive bacilli, with filamentous forms seen in younger cultures, is not distinctive. Key to the identification is the hydrolysis of casein, as seen in the lower photograph. Xanthine was not hydrolyzed. The presumptive identification is:

Oerskovia turbata

The definitions listed below define terms that are used in molecular testing. Match each definition to the term from the drop-down box that it defines.

Oligonucleotide - a short synthetic strand of nucleic acid Probe - A fragment of nucleic acid that is complementary to another nucleic acid sequence; it is labled and used to identify the complementary sequence Target - A specific region of DNA or RNA unique to the organism, mutation or disease that is detected by the molecular testing method

Which EBV markers would be MOST likely positive for an individual who had infectious mononucleosis nine years ago?

Only anti-VCA (IgG) and anti-Epstein-Barr nuclear antigen (EBNA) are positive

Which one of the following results is typical of Campylobacter fetus subspecies jejuni?

Optimal growth at 42 degrees C

The increased resistance of MRSA strains to beta-lactam antibiotics is due to production of which of the following penicillin binding proteins (PBPs)?

PBP 2a

The fungal colony illustrated in the upper image was observed after 4 days incubation at 30 ˚C, and recovered from dialysis fluid of a 60 year-old patient who had been receiving multiple antibiotics for treatment of bacterial peritonitis. The lower image is of microscopic view of a lactophenol blue stained mount taken from a small sampled of the surface of the colony. Note the distinctly pointed phialides from which long chains of small, spherical conidia are derived. Based on the colony morphology and microscopic features as observed in the lactophenol stained preparation, the identification is:

Paecilomyces

MacConkey agar contains all of the following except: Select one: a. Penicillin b. Bile salts c. Lactose d. Crystal violet

Penicillin

Which type of healthcare occupational exposure has the greatest risk of HIV transmission?

Percutaneous injury

A 40-year-old business man developed intermittent spiking fevers one week following a trip to Western Africa. The Wright-stained peripheral blood smear as illustrated in the image was observed. Based on the morphology of the erythrocytes and the heavy invasion with ring form trophozoites, the diagnosis of malaria could be made. With particular focus on the sickle-form gametocyte, which Plasmodium species is represented by the peripheral blood smear?

Plasmodium falciparum

The suspicious form was recovered in blood. Please identify the species listed below that matches the parasites shown in the image with arrows.

Plasmodium falciparum

Thick Giemsa-stained smears are primarily used to screen for the presence of

Plasmodium species

The condition most likely to predispose a person to septicemia by viridans streptococci is:

Poor oral hygiene

The colonies illustrated in the composite blood agar/MacConkey agar to the left were recovered from an inflammatory infection of the oral cavity of a 16-year-old student. The colonies on both agar plates incubated anaerobically are small, entire, and smooth with a light gray-yellow pigmentation. Small gram-negative rods arranged singly and in loose clusters had been observed microscopically in a gram-stained preparation. Spot indole and lipase reactions are positive. Note in the image to the right the alk/alk non-fermentative carbohydrate reaction on Kligler Iron agar, with lack of fermentation of the sugars presented in the tubes the the right (asaccharolytic). Select from the multiple choices the name of the anaerobic, asaccharolytic, gram-negative isolate.

Porphyromonas asaccharolytica

Illustrated in the photographs are smooth, entire, gray-white colonies growing on blood agar (left image) that are faintly beta hemolytic. Light pink-red pigmented entire, smooth colonies on MacConkey agar are shown in the image to the right. These isolates were recovered from a skin infection incurred by a 28 year old man after swimming in a lake. The pink-red pigmentation of colonies on MacConkey agar suggest lactose fermentation. Biochemical reactions included Acid/Acid KIA reactions indicating fermentation of glucose. Oxidase was positive. Other positive reactions include indole, DNA'se, and esculin. Additional biochemical tests identified this isolate as Aeromonas species. The pink-red colonies growing on MacConkey may suggest one of the Enterobecteriaceae. From the multiple choices, select the key presentation that excludes this possibility. a. Beta hemolysis on blood agar b. Pink red colonies on MacConkey Agar c. Positive oxidase reaction d. Positive esculin reaction

Positive oxidase reaction

Each of the following properties inherent in a bacterium contribute to the virulence except:

Production of opsonins

The reactions observed in this Kligler Iron Agar slant (left) and Christensen's urease slant (right) provide the presumptive identification of:

Proteus Mirabilis

The bacterial species producing the swarming on the surface of the 5% sheep blood agar plate shown in the photograph was indole negative. The most likely identification is:

Proteus mirabilis

Prior to receiving antibiotic therapy, a patient had a urinary tract infection with gram-negative, motile rods producing the following reactions: Indole: pos. H2S (TSI): pos. MR: pos. VP: neg. Phenylalanine deaminase: pos. Urea: pos. Citrate: pos. Ornithine decarboxylase: neg. Gelatin hydrolysis: pos. Based on the reactions above, what organism is MOST likely causing the infection?

Proteus vulgaris

Sodium thiosulfate is often added to selective culture media to:

Provide sulfur atoms for H2S positive isolates

Illustrated in this photograph is a Pseudo F agar slant after inoculation and incubation with an unknown bacterial species. The bright blue-fluoresce when observed with a UV light indicates that the unknown is most likely:

Psuedomonas putida

The test used for the indentification of specific capsular serotypes of Streptococcus pneumonia is:

Quellung

The core (genome) of the HIV viron contains:

RNA

The disappearance of HBsAg and HBeAg, the persistence of anti-HBc (total), the appearance of anti-HBs, and often of anti-Hbe indicate:

Recovery phase of HBV infection

The Xylose Lysine Decarboxylase medium shown in this photograph was isolated from a stool specimen on an immunocompetent adult. Your best action would be to:

Report it as no Salmonella or Shigella isolated.

On a plate growing S. pneumonia, the zone of inhibition around the disk shown in the image has been measured at 23 mm. Based on this result, you should:

Report oxacillin-susceptible

If a CAMP test had an arrowhead appearance, the bacitracin disk had a zone of 6 mm with a 6 mm disk, the bile esculin was tan throughout, and the SXT disk had a zone of 6 mm with a 6 mm disk, the action you should take would be:

Report the isolate as Beta streptococcus Group B

Which of these laboratory methods are recommended for confirmation of influenza A H1N1 subtype infection?

Reverse transcriptase-polymerase chain reaction (RT-PCR)

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 37 degrees C. In the photomicrograph, clusters of gram-positive cocci were observed microscopically in a gram stain prepared from one of the colonies. The coagulase reactions are pictured in the lower images. With these observations, select the name of this isolate from the multiple choices as listed.

S. aureus

Which one of the following does NOT have capsular material as a defense mechanism?

S. aureus

Which of the following yeasts listed below is known as brewer's or baker's yeast?

Saccharomyces cerevisiae

Multiple young 3-day old colonies having a low cottony surface mycelium that upon maturity develop a distinctly gray pigmentation (referred to as "house mouse gray"). The reverse of the colony remains light gray in color and does not show the darker pigmentation. Microscopic examination of a small inoculums from the surface of the colony is illustrated in the lower photomicrograph. From the list of multiple choices, select the genus name of the fungus being represented.

Scedosporium

This suspicious form, found in urine, measures 120 micrometers by 50 micrometers.

Schistosoma haematobium

The portion of a tapeworm used for attachment to the host's intestine is called the:

Scolex

An isolate of S. pneumoniae from a respiratory specimen gave a zone of inhibition of 18 mm around a 1 ug oxacillin using the disk diffusion test. What should the next step be?

Set up an MIC on the isolate

The appearance of the bacterial colonies growing on the surface of the Hektoen Enteric agar plate shown in this photograph are consistent with each of the following bacterial species except: Serratia marcesens Shigella sonnei Klebsiella oxytoca Enterobacter sakasakii

Shigella sonnei

Which of the following are the most frequently associated with infective endocarditis? Select two of the choices provided. Select one: Viruses Neisseria Staphlyococci Streptococci

Staphlyococci Streptococci

Who are we huddled here so tight,Like clusters of stars in the night.

Staphlyococcus epidermis

This is a catalase-positive, coagulase-negative gram-positive coccus isolated from a urine specimen from a 20-year-old college student. The image below is a Mueller Hinton plate streaked with a 0.5 MacFarland standardized inoculum and a 5 microgram disk of novobiocin after overnight incubation. What is the identification of the isolate?

Staphylococcus saprophyticus

The observation of darkly pigmented colonies on blood agar as illustrated in this photograph is somewhat of a surprise. The colonies of each of the following bacterial species may have an appearance similar to that seen here except:

Stentotrophomonas maltophilia

The Optochin (ethylhydrocupreine hydrochloride) disc is MOST often used for the identification of which organism

Streptococci pneumoniae

Tiny, gray-white colonies growing on the surface of chocolate agar were initially thought to be Haemophilusspecies. Consistent with this observation, streaks of colony growth had been observed adjacent to a beta hemolytic Staphylococcus test streak. A gram stain of this isolate is pictured here taken, from this blood agar plate. What presumptive identification can be made?

Streptococcus anginosus (milleri)

A paitent was admitted to the hospital recently with an obvious infection. A sputum specimen was submitted and the microbiologist inoculated it to sheep blood agar. Based on the colony morphology and the alpha hemolysis seen in the image to the right, the most likely identification is:

Streptococcus pneumonia

Observe the Optochin "P" disc reaction illustrated in the upper left photograph on the surface of blood agar. Heavy growth of tiny, alpha hemolytic colonies are observed growing on the agar surface that extend to the outer margins of the paper disc. The gram stain presented in the lower photomicrograph reveals small gram-positive cocci lying singly, in small clusters, and more typically in long chains. This isolate has been recovered from blood cultures in cases of post-valvular endocarditis. From the list of multiple choices, select the presumptive identification of this isolate.

Streptococcus viridans

The colonies growing on Middlebrook agar shown in the upper left photograph were recovered after 5 days incubation from an aspirate of a superficial skin infection. Gram stain revealed branching bacilli as seen in the lower image. These were non-acid fast. Illustrated in the upper right photograph are colonies growing on casein medium demonstrating hydrolysis. The presumptive identification is:

Streptomyces species

The target cell of the AIDS virus is the

T lymphocyte

A cyst was found in a human brain biopsy with characteristics of cysticerus. These cysts may develop also in other body sites, particularly in the lungs. Cysticercosis in humans most commonly occurs as part of the life cycle of a tapeworm, the species of which is indicated by the proglottid shown in this image, From these observations, what is the name of the tapeworm of which cysticercosis is part of its life cycle?

Taenia solium

What is the source of the HIV envelope?

The host cell membrane

What is the identifying characteristic of Aureobasidium pullulans?

The production of a black yeast-like colony

The federal government has categorized critical biological agents into three groups: A, B, and C. Why are the agents in category A classified as the highest priority?

These organisms can be easily disseminated or transmitted person-to-person

Which of the following is a characteristic of Francisells tularensis?

Tiny, weak-staining, gram-negative coccobacilli

Illustrated in the photomicrograph is a Giemsa-stained impression smear prepared from an aspirate of an enlarged cervical lymph node. Human infections are acquired through the ingestion of poorly cooked meat. Pregnant women in particular are advised to avoid handling of cats and the ingestion of under-cooked meat. Based on the morphology of the 8 um long tachyzoites observed in the photomicrograph, select the name of the protozoan parasite as listed for making a presumptive identification.

Toxoplasma gondii

Illustrated in the upper photograph is a 50 mm long nematode adult worm primarily found in the cecum in cases of human infection. Rectal prolapse may be a complication if infection is heavy. These adult worms are not observed in stool specimens but more commonly may be seen embedded in the epithelium of a prolapsed rectum. The identification can be made by observing the characteristic ovum in fecal specimens as illustrated in the high-power lower photomicrograph. From the multiple choices listed below, select the presumptive identification.

Trichiuris trichiura

Illustrated in the photomicrograph is the tail portion of an adult worm of a filarial nematode. Human infections with this nematode are more commonly found among those living in Southeast Asia, but may be observed in recent travelers there and to surrounding regions. These adult worms measure up to 300 um, occupy lymphatic channels and may cause lymphatic obstruction. Varying degrees of fever and chills may be experienced. The species indicated in this exercise by orientation of nuclei within the tail section (arrows), more commonly involves the lymphatics of the genital tract resulting in orchitis and hydrocele. From the nematode species listed below, indicate the most likely species identification.

Wuchereria bancrofti (best guess)

A small gram-negative rod isolated from an eye grows on chocolate agar but NOT on sheep blood agar. It produces satellite growth around staphylococci on sheep blood agar, however. The organism requires:

X and V factor

Assume you perform microbiology for an institution submitting surveillance cultures for MRSA. Which isolate should receive further workup to rule out methicillin (oxacillin) resistance?

Yellow colonies on Mannitol Salt agar; catalase-positive, coagulase-positive.

Which of the following HPV types are most likely to be associated with cervical cancer?

16 and 18

Illustrated in the upper image is a stained histological section of bowel illustrating a heavy inflammatory reaction within which 10-12 um spherical cysts are observed. The lower image is a close in view of one of these cysts as seen in a smear preparation of the exudates. Based on these observations, select from the list of multiple choices the disease that can be presumptively reported.

(one of the three) Balantidiasis Amebiasis Cysticercosis

If a Brucella species is suspected in a blood culture it should be held for a maximum of how many days on a commercial blood culture system?

10-14

Illustrated in the upper composite photograph are non-hemolytic, smooth, entire non-pigmented white colonies growing on blood agar. Human isolates are most commonly from nosocomial infections related to endotracheal tubes and tracheostomies, with peritonitis inpatients receiving peritoneal dialysis. Distinctly light lavender-pink pigmented colonies are observed growing on MacConkey agar. Tiny coccobacilli simulating those of Neisseriaspecies are observed in gram stains as illustrated in the lower photmicrograph. Other identifying features include the oxidative production acids from most carbohydrates (saccharolytic) and a negative oxidase test. From these observations, select from the multiple choices the presumptive identification of this isolate.

Acinetobacter baumannii

Illustrated in the top image are small, entire gray-white colonies growing on the surface of an anaerobic blood agar plate. Hemolysis is absent. Small, gram negative coccobacilli with rounded ends are seen on gram stain. Positive biochemical reactions include strong hydrolysis of esculin, positive indole and the fermentation of glucose and other carbohydrates (saccharolytic). From these observations, select the correct identification of this isolate from the choices below:

Bacteroides fragilis

Illustrated in the top image is a 10-day-old colony growing on the surface of Sabouraud Dextrose with Brain Infusion (SABHI) agar, incubated at 30 degrees C, recovered from an induced sputum sample obtained from a 42 year-old Mid-western farmer. The colonies are not genus/species specific, and appear as a mold with delicate, silky, cob-web like yellow-white mycelium. The species identification is made by observing the Lactophenol blue-stained tease mount preparation illustrated in the bottom image. With these observations, select the presumptive identification of this isolate from the choices shown below.

Blastmyces dermatitidis

Within three days at 28°C a sputum specimen placed in Sabouraud's dextrose agar with chloramphenicol and cycloheximide produced moist, grayish growth, with a white aerial mycelium, the organism is MOST likely:

Blastomyces dermatitidis

Within three days at 28°C a sputum specimen placed in Sabouraud's dextrose agar with chloramphenicol and cycloheximide produced moist, grayish growth, with a white aerial mycelium, the organism is MOST likely:

Blastomyces dermatitidis ?

The pair of nonfermentative gram negative bacilli producing the motility reactions illustrated in the left (motile) and right (nonmotile) tubes respectively shown in the photograph are:

Bordetella bronchiseptica and Acinetobacter baumannii

Illustrated in the upper photograph of the composite is the surface of a blood agar plate on which small, entire, gray-yellow colonies are observed, with yellow pigmentation shown on the cotton swab. Light pink, non-fermentative colonies are seen on MacConkey agar (composite upper right), confirmed by the Alk/Alk reaction on KIA (left tube in composite lower image). Shown in this composite also are key reactions - positive lysine decarboxylase (center), and oxidative utilization of maltose and sucrose (right). This non-fermenter is most commonly an opportunistic pathogen in cases of respiratory infection associated with chronic granulomatous disease and cystic fibrosis. From these observations, select from the multiple choices the identification of this isolate.

Burkholderia cepacia

After a one week visit in the Philippines, a 42-year-old male missionary had noticed a gradual onset of abdominal pain, belching, and intermittent diarrhea during the past month. Upon further examination, dehydration and electrolyte imbalances with low plasma levels of potassium, sodium, and calcium were detected. The 60 um ovum, as illustrated in the image, was observed in a stool preparation. Select the presumptive identification from the answer choices shown below.

Capillaria philippinensis

The irregular-sized, gray-white colonies, with irregular margins as shown in the image to the left in the upper composite photograph were recovered from a stool specimen in a case of antibiotic associated colitis. The colonies are flat, gray-white and spreading with irregular margins. Some patients with this infection develop pseudo-membanous colitis that can be life threatening. Growth is enhanced when Cycloserine-cefoxitin-fructose agar (CCFA) is used, as seen in upper right photograph. The observation of elongated, gram positive bacilli with distinctive sub-terminal and central spores in gram stain mounts provides for a presumptive identification. An additional key identifying biochemical reaction is the hydrolysis of esculin and gelatin. With these observations, select from the multiple choices the presumptive identification of this isolate.

Clostridium difficile

Oral candidiasis may be directly exacerbated by the habitual ingestion of:

Cola

________________ is predominantly associated with skin and soft tissue infections (SSTIs), such as abcesses, cellulitis, folliculitis and impetigo.

Community-associated MRSA

The story might be told that a pathologist, when first viewing an H & E - stained section of an endoscopic biopsy of duodenum (upper left image), may seek a consultation. The specimen was obtained from a patient with a malabsorption syndrome. After observing tiny acid-fast globules along the intestinal epithelial lining cell (arrows, upper right image), one of the laboratory microbiologists was consulted for an answer. Having presumptive identification in mind (lower left image), the microbiologist prepared an acid-fast stained smear of intestinal fluid (lower right image) and observed tiny 5 um in diameter oocysts. From the multiple choices listed, select the presumptive identification, select what parasite the microbiologist might have reported.

Cryptosporidium parva

The infective stage for the majority of all intestinal amoebae is the

Cyst

The colonies illustrated on the blood and chocolate agar plates represent a slow-growing bacterial species that is endogenous in the oral cavity and upper respiratory tract, but may be recovered from human bite skin infections incurred during fist fights. Note the pitting of the agar surrounding the colonies growing in the chocolate agar plate. The Alk/Alk non fermentative reaction seen in the Kligler Iron Agar tube to the left in the lower photograph indicates the non fermentation of glucose, also indicated by the lack of carbohydrate assimilation in the individual carbohydrate reaction tubes to the right of the KIA tube. A reduction of nitrate demonstrated and decarboxylation of ornithine are the positive reactions included in this exercise. From these observations, select from the multiple choices identification of this bacterial isolate.

Eikenella corrodens

The 6 um in diameter cyst illustrated in the trichrome-stained photomicrograph was inadvertently observed in the stool specimen that was being examined for reasons not clinically related to a parasitic diseases. Further history revealed that the patient for whom the stool examination was being performed had only rare bouts of mild diarrhea. From the multiple choices listed below, select the appropriate genus/species designation to enter in the laboratory report to be sent out.

Entamoeba histolytica/dispar

The 30 X 50 um ovum illustrated in the image are most commonly observed by microscopic examination of transparent adhesive tape mounts of perianal skin of children who have complained of nocturnal anal pruritus. From the list of answer choices below, select the most likely presumptive identification.

Enterobius vermicularis

A large number of antigen detection procedures and assays are available to diagnose clinically suspected parasitic diseases in the absence of the finding of ova or other forms of parasites in preparations of stool or other body fluids. Illustrated in the photograph are antigen positive-staining green dots at sites where small drops of duodenal aspirated fluid had been applied to the test reagents. Trophozoites of this protozoan occupy the upper gastrointestinal tract and the excreted ova may not find the way down the long stretch of bowel to be excreted in stool specimens. From the list of multiple choice selections, indicate the genus/species in which antigen detection may be required to make a diagnosis.

Giardia duodenalis

Detection of antigens in clinical specimens when parasites are observed in stool specimens is the current test of choice for identification when a diagnosis is in doubt, providing an increased sensitivity over more common microscopy techniques. Several commercial products (DFAs, EIAs, and rapid tests) are available. Illustrated in the photomicrograph is an H & E - stained tissue section of duodenum illustrating the presence of an intra-luminal intestinal trophozoite in which an antigen assay of duodenal fluid might be helpful in making a definitive identification. Select from the multiple choices the presumptive identification.

Giardia duodenalis

Illustrated in this photomicrograph is a silver-stained section are duodenal epithelial cells invaded by 1.5 um in diameter spores (arrows). They appear red in the Weber-stained mounts (image not shown here). The presumptive identification is:

Microsporidium species

Observation of each of the following characteristics is helpful in differentiating between Nocardia species and Mycobacteriumspecies except: Select one: Partial acid fast staining Filamentous rods that branch Musty basement smell of the colonies Gram positive staining

Gram positive staining

A 42-year-old chain smoker experienced an increase in cough, sputum production, and intermittent shortness of breath for over one week. A diagnosis of chronic bronchitis with acute exacerbation was made. The image shows a Gram stain of an early morning, spontaneously expectorated sputum. Based on the pleomorphic coccobacilli shown in the Gram stain, what is the most likely cause of the exacerbation?

Haemophilius influenza

A 21-year-old female developed painful swelling of the left knee associated with low grade fever. The knee was painful to palpitation, an effusion was evident, and the overlying skin was slightly erythematous. Fluid was aspirated and a direct Gram stain was performed (see image). Based on the Gram stain morphology, which of the following bacterial species is LEASTlikely to serve as the etiologic agent in the case described?

Haemophilus influenza

The presumptive diagnosis of fungal infections mey be made based on the location of sites of visit in which they became endemic. One such condition, is colloquially referred to as "Spelunker's Scourge". This condition occurs after a tour or work in underground caves located in the Midwest, where dust contaminated with bird and bat dung is inhaled. Select the name of the fungus from the choices shown below that causes this endemically-acquired respiratory infection.

Histoplasma capsulatum

Which one of the following statements about E.coli O 157:H7 is false: Select one: It has been reported in contaminated unpasteurized milk, unpasteurized apple juice, and under cooked hamburger It can cause hemolytic-uremic syndrome in children It causes hemorrhagic diarrhea, abdominal pain, and other symptoms It ferments sorbitol rapidly

It ferments sorbitol rapidly

Which one of the following statements about Coxiella burnetii is not true: Select one: a. It causes Q fever b. It has a worldwide distribution c. It is an obligate intracellular parasite d. It is best diagnosed by culture of the organism

It is best diagnosed by culture of the organism

Which one of the following statements about Coxiella burnetti is not true:

It is best diagnosed by culture of the organism

In cases where more severe symptoms may occur, particularly in progressive anemia, what additional test procedure should be performed to determine the role that hookworm infection may play when ova are detected in stool specimens?

Make a quantitative count of the number of ova present

Small, gray-white colonies, as observed growing on 7-H10 agar to the left in the upper composite photograph, were recovered from an upper respiratory specimen after 7 days incubation. This Mycobacteriumspecies in the pas was uncommonly recovered from human infections until the advent of AIDS when it became an agent of pulmonary and other infections. Notably, colony isolates from patients with AIDS have developed a pale yellow pigmentation that does not intensify with light exposure (right image in upper composite photograph). The acid-fast bacilli as observed in the lower photomicrograph are short and lie singly or in loose clusters. From these observations select from the multiple choices the presumptive identification of this isolate.

Mycobacterium avium/intracellulare

Illustrated in the photograph are 14 day-old colonies of a Mycobacterium species growing on Middlebrook 7H-10 agar, with development of yellow pigmentation after exposure to environmental light. From the choices listed below, select the correct presumptive identification of this photochromogenic Mycobacterium species.

Mycobacterium marinum

Illustrated in the top mage are colonies after 12 days of incubation of a Mycobacterium specied that developed a yellow pigmentation upon exposure to light (photochromagen). A positive niacin accumulation reaction is shown in the lower image suggestive of M. tuberculosis, a species that can be ruled out because of the colony pigment production. From the multiple choices, select the name of this photochromogenic Mycobacterium species.

Mycobacterium simiae

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.

Mycobacterium tuberculosis

Small intracellular gram-negative cocci were observed in a centrifuged spinal fluid sediment as presented in the upper photomicrograph. A clinical diagnosis of meningitis was suspected. Yellow-gray colonies after 24-hour incubation had been observed on blood agar. Based on the carbohydrate utilization tube reactions observed in the lower photograph, select from the multiple choices the presumptive identification of this isolate.

Neiserria meningitidis

Which of the following parasites enters its host through ingestion of infected pork?

Trichinella spiralis

In observing the slow-growing , 7-day-old dark brown colonies growing on Sabouraud Dextrose with Grain Heart Infusion (SABHI) agar, note the black pigment that extends to the reverse of the colony. This provides for 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. From the list of choices below, select the identification of the fungal species presented.

Phialophora verrucosa

A flagellar strain would show peritrichous flagellae for each of the following organisms except: Select one: Bordetella bronchiseptica Alcaligenes faecalis Pseudomonas aeruginosa Escherichia coli

Pseudomonas aeruginosa

The colonies shown in the blood (BAP) agar (upper) and MacConkey (MAC) agar (lower) biplate are a 24 hour growth from an aerobic blood culture bottle that became positive at 12 hours after inoculation. The appearance of the colonies on MAC agar rules out the following two bacterial species: a. Pseudomonas aeruginosa b. Klebsiella pneumoniae c. Streptococcus pneumoniae d. Escherichia coli

Pseudomonas aeruginosa Streptococcus pneumoniae

Common colds are MOST often associated with which agent?

Rhinovirus

The ovum as illustrated in the high-power photomicrograph, averages 140 um. The ova are most commonly observed in a urine sediment from a patient complaining of frequent urination, dysuria, hematuria and recurrent urinary tract infections. Note the characteristic delicate, sharply pointed terminal spine (blue arrow) extruding from the anterior margin of the shell. From the multiple choices listed below, select the presumptive identification of this ovum.

Schistosoma haematobium

Illustrated in the top photograph are alpha-hemolytic, entire, gray-white convex colonies that are of a bacterial species that was found to be susceptible to vancomycin. In the lower photomicrograph are shown gram-positive cocci arranged in chains and in loose clusters that are not species distinctive. Select from the multiple choices the bacterial species that are uncommonly vancomycin resistant.

Streptococcus species

What is the primary target of HIV?

T-helper cells

Illustrated in the photograph is a single proglottid representative of one of the cestode tapeworms. The proglottid is longer than wide and has well over 13 lateral uterine branches. Select the presumptive identification of this tapeworm proglottid

Taenia saginata

Chlamydia trachomatis causes which of the following problems?

Trachoma, a major cause of preventable blindness in the world

Illustrated in the composite photograph is an inflammatory reaction of skin with erythema and micro-pustule formation, most consistent with a dermatophyte infection. The lactophenol blue mount was prepared from a 4-day old colony grown from the skin lesion as shown. The accompanying lactophenol blue microscopic mount illustrates small, spherical micro conidia arranged in loose clusters along the sides of thin hyaline hyphae. The species identification can be confirmed by the positive urease reaction as shown. Select from these observations the species

Trichophyton mentagrophytes

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.

Trichophyton rubrum

Illustrated in the top photograph is 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 frame) and the underlying chains of pigmented chlamydospores among the hyphae (lower frame) as seen in this composite image. With these observations, select the identification of this dermatophyte.

Trichophyton verrucosum

The 60 um ovum illustrated in this image was recovered from a diarrheal stool specimen from a 30-year-old male one month after a visit in Puerto Rico. Dysentery, abdominal discomfort and low grade diarrhea had been experienced. Select the most likely genus//species identification from the choices below.

Trichuris trichiura

The fastidious gram negative bacillus featured here has been recovered from individuals in pandemic outbreaks of diarrhea after ingestion of contaminated stream, lake, or well water. In many cses, life-threatening profuse diarrhea resulting in dehydration and electrolyte loss is often experienced. Smooth, entire, convex light gray yellow colonies are observed on blood agar (left upper image). Note the yellow pigmentation of the colonies growing on TCBS agar (Thiosulfate Citrate Bile Sucrose) on the right of the composite image, indicating strong acid production from sucrose. Cytochrome oxidase is also positive. Small, curved and S-shaped, gram-negative bacilli are seen on Gram stain. From these observations, select from the multiple choices the correct genus/species identification of this isolate.

Vibrio cholerae

The stool specimen from a patient admitted to the hospital with symptoms of appendicitis has a culture with the following characteristics: Gram-negative bacillus Catalase positive Urease positive Weakly fermentative TSI Slant is A/A These reactions suggest that the organism is MOST likely:

Yerseinia enterocolitica

Which of the following statements concerning C. difficile is NOT true? Select one: a. It is the causative agent of an inflammatory condition of the large intestine. b. It is an aerobic organism. c. It produces potent toxins. d. It produces spores

b. It is an aerobic organism.

What is the MOST common infective agent to be transmitted through blood transfusion that results in morbidity and mortality?

bacteria

The ONPG (ortho-nitrophenyl-Beta-D-galactopyranoside) test should be used to determine what?

separation late lactose fermenters from lactose negative bacteria