Micro for exam
Based on the structures observed in this photomicrograph, the most probable species of the fungus recovered from an induced sputum specimen
Aspergillus nidulans
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
The media used to isolate Legionella pneumophilia should contain which of the following additives?
Charcoal and yeast extract
Which one of the following is the INCORRECT match between organism and the appropriate diagnostic procedure? a. Trichinella spiralis - serologic testing b. Cryptosporidium - modified acid-fast stain c. Echinococcus granulosus - routine ova and parasite examination d. Schistosoma haematobium - examination of urine sediment e. Mycobacterium tuberculosis - acid fast stain
Echinococcus granulosus - routine ova and parasite examination
The long, pencil-shaped, multi-celled, thin, and smooth-walled macroconidia illustrated in this image are characteristic of which species?
Exserohilum species
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.)
Glutamate dehydrogenase (GDH) antigen assay Antigenic detection of toxins A and B
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
Which one of the following descriptions about Pasturella is FALSE? 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.
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:
Indole: Escherichia coli and Proteus mirabilis
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
Which bacterial species is a common agent of neonatal bacteremia?
Listeria monocytogenes
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
Klebsiella pneumoniae
f 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 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
Sodium thiosulfate is often added to selective culture media to:
Provide sulfur atoms for H2S positive isolates
A flagellar strain would show peritrichous flagellae for each of the following organisms except: a. Bordetella bronchiseptica b. Alcaligenes faecalis c. Pseudomonas aeruginosa d. Escherichia coli
Pseudomonas aeruginosa
Neisseria meningitidis
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:
Schistosoma haematobium
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.
Chlamydia trachomatis causes which of the following problems?
Trachoma, a major cause of preventable blindness in the world
The end product of the fermentative metabolism that characterizes members of the Enterobacteriaceae is:
Various mixed acids
Stenotrophomonas maltophilia and Burkholderia cepacia share each of the following EXCEPT for which characteristic?
Cytochrome oxidase activity
What two glycoproteins are expressed on the surface of influenza A viruses and are used for subtyping of the viruses?
Hemagglutinin Neuraminidase
Which of the following species of Mycobacteriummight be associated with contamination of the hot water system in large institutions such as hospitals
M. xenopi
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
Any laboratory that analyzes microbes or refers specimens that have the potential to contain microbial agents or toxins is a sentinel laboratory.
True
The bacterial species illustrated in these photographs was recovered from the septic peritoneal fluid of a patient undergoing continuous peritoneal dialysis. The most likely identification is:
Micrococcus luteus
Each of the following tests is helpful in the species identification of Staphylococcus aureus except
Modified dimethyl sulfoxide (DMSO) test
Tiny translucent gray colonies were recovered on a blood agar from a patient with purulent conjunctivitis. Gram-negative diplococci were seen on a gram stain. Colonies growing at a margin of inhibition of 10 ug/mL penicillin disk. This is most likely what? A Moraxella lacunata B Nesseria sicca C Acintobacter baumanni D Nesseria gonorrhea
Moraxella lacunata - they are elongated pleomorphic filaments
Scedosporium
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 surfaces of the colony is illustrated in the lower photomicrograph. From the list of multiple choices, select the genus name of the fungus being presented
ASO b. anti-DNAse
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
Select from the multiple choices the specimen that is inadequate for the recovery of anaerobes and should be summarily rejected upon receipt in the microbiology laboratory.
Uterine cervical swab in Cary-Blair transport medium
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. Select one:
Vegetable artifact
Lower left quadrant
Which of the hyaline mold colonies that are represented in the composite picture on the right is typical of Penicillium species?
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 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
Tryptophan
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:
As a gram positive coccus,I've become a bit fancy Short chains and motile, plus I carry the gene VanC.
not sure
Match the hepatitis B test with the appropriate disease phase. HBsAg Anti-HBs Anti-HBc Anti-HBc
HBsAg late incubation, cute Anti-HBs recovery Anti-HBc IgM acute convalescent Anti-HBc total acute convalescent recovery
Which one of the following statements is true regarding the 2009 H1N1 virus?
In 2009, the novel H1N1 virus spread during warmer months
A one of the morphological families of parasites, features that characterize various Nematode species include
Disease may be transmitted via a direct fecal to oral route Filariform larvae may serve as an infective form for humans
Which one of the following statements about Coxiella burnetii is not true:
it is best diagnosed by culture of the organism
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:
it is not Coccidioides immitis, or Histoplasma capsulatum
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
I smear the streak line throughAnd grow best at forty two.
Campylobacter jejuni
The infective stage for the majority of all intestinal amoebae is the:
Cyst
The age groups that have been most affected by the H1N1 virus are children and younger adults.
False
In a HPV infection, where does the viral DNA replicate?
Squamous epithelial cell
Enterobacter cloacaecolonies 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
The glycoproteins associated with the HIV "spike" are:
120 and 41
Listeria monocytogenes
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
Which of the following are useful serological tests to document antecedent Streptococcal infections:
ASO anti-DNAse
Capillaria philippinensis
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.
Erysipelothrix rhusiopathiae
Among the gram-positive bacilli, the unique species producing H2S as seen in the Kligler Iron Agar slant illustrated in this photograph is:
A major difference between Salmonella enterica and Shigella infections is that ONLY in salmonellosis can which of the following be observed?
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
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
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
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
The stage of viral replication where the envelope is being acquired and the HIV is leaving the host cell is known as:
Budding
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
Which of the following organisms causes thrush
Candida albicans
The top image is characteristic of the clinical presentation of oro-pharygeal thrush that may be observed in patients with AIDS. Specimen samples sent to the mycology laboratory for culture often grow yeast colonies on agar plates within 2-3 days of incubation at 30˚ C. Observed in the bottom photograph is the surface of a niger seed agar plate on which are growing inoculation streaks of two different yeast species, the one to the left representing the clinical isolate, the one to the right a control strain. It is important to recognize the colonies of the clinical isolate as it may be potentially resistant to commonly used anti-fungal agents. Select from the multiple choices the species of yeast involved in this infection.
Candida dubliniensis
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. These 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
Which of the following fungal infections is endemic in the southwestern US desert regions?
Coccidioidomycosis
______________________ is predominantly associated with skin and soft tissue infections (SSTIs), such as abscesses, cellulitis, folliculitis, and impetigo.
Community-associated MRSA
The Chinese transcription shown here is most consistent with the cell morphology of:
Corynebacterium diphtheriae
Which one of the following organisms is commonly cultured from the nasopharynx of healthy people but is RARELY pathogenic: a. Beta hemolytic streptococci b. Corynebacterium species c. Haemophilus influenzae d. Neisseria meningitidis e. Staphylococcus aureus
Corynebacterium species
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
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.
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
I reside in the mouth where I measure approximately 17 micro meters
Entamoeba gingivalis trophozoite
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
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
Which two of the following organisms are gram-positive? Select one or more: a. Pasteurella b. Erysipelothrix c. Aeromonas d. Lactococcus
Erysipelothrix Lactococcus
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
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
Illustrated in the photograph is a large trematode fluke averaging 30 - 70 mm. This fluke resides primarily in the small intestine. Characteristic is the rounded cephalic end, the convoluted uterus in the anterior half of the fluke and a delicate branching testes in the posterior half. Humans become infectd by ingesting metacercaria contaminated water vegetables. From the list of multiple choices, select the presumptive identification.
Fasciolopsis buski
Each of the following characteristics will differentiate between Listeria monocytogenes and Erysipelothrix rhusiopathiaeexcept:
Fermentation of glucose
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 the bacterial 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?
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 isolat
Geotrichum candidum
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 presumptive diagnosis of fungal infections may 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
The transmission of which of the following organisms is associated with the guano of bats?
Histoplasma capsulatum
The most common rapid slide test (MONOSPOT©) for infectious mononucleosis employs:
Horse erythrocytes
Microsporidium species
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.
Mycobacterium marinum
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. a. Mycobacterium chelonae b. Mycobacterium marinum c. Mycobacterium scrofulaceum d. Mycobacterium gordonae
Acinetobacter baumannii
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.
Helicobacter pylori
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:
Which one of the following comments about Francisella is not true?
Is a strict anaerobe
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. Antibiotic susceptibility: Carboxicillin and ampicillin resistant, all others sensitive.What is the MOST likely organism?
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
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
Streptococcus viridans
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.
s 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
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
MacConkey agar contains all of the following except:
Penicillin
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 to 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.
Positive oxidase reaction
Each of the following properties inherent in a bacterium contribute to the virulence except: a. Presence of a polysaccharide capsule b. Production of a proteolytic enzymes c. Production of opsonins d. Presence of surface membrane attachment receptors
Production of opsonins
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
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
Which of these laboratory methods are recommended for confirmation of influenza A H1N1 subtype infection?
Reverse transcriptase-polymerase chain reaction (RT-PCR)
Which one of the following does NOT have capsular material as a defense mechanism?
S. aureus
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 dimorphic fungus that may produce black, yeast-like colonies after prolonged incubation at 37˚ C is:
Sporothrix schenckii
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
Staphylococcus aureus
The Optochin (ethylhydrocupreine hydrochloride) disc is MOST often used for the identification of which organism?
Streptococci pneumoniae
In cases of suspected intestinal parasitic disease, select the name of the parasite, as illustrated by the 50 um ovum in this image, that may be detected in upper respiratory secretions when stool specimen preparations are negative.
Strongyloides stercoralis
Moraxella catarrhalis
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:
The target cell of the AIDS virus is the:
T lymphocyte
Taenia spp.
The 40 um in diameter ovum illustrated in the photograph may be observed in the stool specimens of individuals presenting with minimal abdominal discomfort and low grade diarrhea. Pairs of hooklets are observed internally in the absence of an internal membrane. Select from the multiple choice answers the presumptive identification of this cestode ovum.
Cardiobacterium hominis
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.
Cunninghamella species
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
Proteus mirabilis
The reactions observed in this Kligler Iron Agar slant (left) and Christensen's urease slant (right) provide the presumptive identification of:
Streptococcus anginosus (milleri)
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?
Which of the following parasites enters its host through ingestion of infected pork?
Trichinella spiralis
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
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.
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
Infectious disease processes in which large numbers of activated macrophages and histiocytes are collected at the site of inflammation is called:
Granulomatous
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
Beta Streptococcus, group A
Which of the following HPV types are most likely to be associated with cervical cancer?
16 and 18
Haemophilus 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?
Group F
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:
Plasmodium falciparum
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?
Haemophilius influenza
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?
Which of the following two media are appropriate for Bordetella pertussis
Bordet-Gengou media Regan-Lowe charcoal agar
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
Demonstration of the organisms in peripheral blood
A definitive diagnosis of malaria can be made by:
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 test(s) that are the most useful in separating Listeria monocytogenesfrom Erysipelothrix rhusiopathiae? a. Room temperature motility b. Catalase c. Esculin hydrolysis d. All of the above
All of the above
Which of the following is a presumptive test for the identification of Lancefield group A Streptococcus:
Bacitracin susceptibility
What is the MOST common infective agent to be transmitted through blood transfusion that results in morbidity and mortality?
Bacteria
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
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
The Epstein-Barr Virus is associated with which of the following conditions:
Burkitt's lymphoma
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 TEST
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-membranous 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
The Iodine prep method is used to detect which of the following protozoan stages:
Cysts
Trichophyton mentagrophytes
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 identification of this isolate.
Mycobacterium tuberculosis
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 simiae
Illustrated in the top image are colonies after 12 days of incubation of a Mycobacterium species 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.
Bacteroides fragilis
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:
Blastomyces dermatitidis
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 septum sample obtained from a 42-year-old Mid-western farmer. The colonies are not genus/species specific, and appear as a mold with a 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.
Epidermophytons floccosum
Illustrated in the top photograph is a 4-day growth of silky, light gray-white to yellow colonies grown on Sabouraud's dextrose agar and incubated at 30 degrees 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.
Aspergillus terreus
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.
Phialophora verrucosa
In observing the slow-growing , 7-day-old dark brown colonies growing on Sabouraud Dextrose 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.
Serratia marcescens
In the upper bi-plate image are shown colonies growing on MacConkey, and on blood agar (right). Relatively large confluent gray white colonies are observed growing on blood agar, while smaller smooth convex colonies with a deep red pigmentation are growing on MacConkey agar. Note that the pigmentation is confined to the colonies growing on MacConkey agar that does not diffuse into the adjacent agar. In follow up to making a presumptive identification, observe that the colonies growing on the DNA'se agar in the lower image show a positive reaction with clearing of the adjacent agar, compared to the growth of a negative control growing in the streak lines to the left. From these observations, select from the multiple choices the presumptive identification of this isolate.
Hymenolepis nana
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.
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
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
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
n 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
HIV is known as a retrovirus because:
RNA is used as the template for DNA synthesis
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
Neiserria meningitidis
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.
Shigella sonnei
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:
Which of the following are the most frequently associated with infective endocarditis? Select two of the choices provided
Staphlyococci Streptococci
Report it as no Salmonella or Shigella isolated.
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:
Paragonimus westermani
The adult fluke related to the 100 um ovum, as illustrated in the image shown, most commonly inhabits the lung parenchyma. The ovum, as may be observed in a sputum specimen, has a smooth, slightly thickened shell with a prominent shouldered operculum as seen at the left lower end. A developing larvae is observed within, retracting from the inner marginof the shell leaving a clear space. Infections with this fluke are endemic in the orient, in West Africa, in South and Central America and may be observed in patients elsewhere after travel to one of these regions. Humans become infected after ingestion of poorly cooked crab meat or crayfish contaminated with metacercariae. Intermittent chest pain, and cough with occasional spitting up of blood (hemoptysis) may be experienced after infection. From the choices below, select the trematode species related to this ovum.
Pseudomonas aeruginosa Streptococcus pneumoniae
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
Morganella morganii
The colonies shown in this 5% sheep blood agar (left) and MacConkey agar (right) split frame photograph are most likely those of:
What is the source of the HIV envelope?
The host cell membrane
Stentotrophomonas maltophilia
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: a. Prevotella melaninogenica b. Stentotrophomonas maltophilia c. Chromobacterium violaceum d. Pseudomonas aeruginosa
Glucose non-oxidizer
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:
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
Staphylococcus saprophyticus
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?
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.
Schistosoma haematobium
This suspicious form, found in urine, measures 120 micrometers by 50 micrometers. a. Schistosome japonicum b. Pseudoparasite c. Trichomonas vaginalis d. Schistosoma haematobium
In molecular diagnostic testing, hybridization employs complementary base pair binding of a synthetic strand to DNA or RNA
True
In order to speciate a swarming Proteus organism found on an eosin methylene blue agar plate, the BEST approach would be to:
c. determine Indole production, phenylalanine and urease activity
Eikenella corrodens
he 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.
Compared to blood agar media, chocolate blood agar FAVORS the growth of which organisms?
more fastidious bacteria
The ONPG (ortho-nitrophenyl-Beta-D-galactopyranoside) test should be used to determine what?
separation late lactose fermenters from lactose negative bacteria
The Quellung test is useful for which of the following:
serological typing of Streptococcus pneumonia
