| Which of the following media contains the X and V factors necessary for the growth of Haemophilus influenzae: | View Page |
| On sheep blood agar Haemophilus influenzae may exhibit satellite formation around all but which of the following organisms: | View Page |
| Which of the following media is commonly used when performing the Kirby-Bauer disk diffusion | View Page |
| Which of the following is the most suitable specimen for the isolation of Bordetella pertussis: | View Page |
| MacConkey agar contains all of the following except : | View Page |
| Match type of media on the right with media on the left: | View Page |
| Match the organisms on the right with culture medium: | View Page |
| Match the culture media on the right with possible organism on the left: | View Page |
| Match the organism on the right with the most suitable culture media on the left: | View Page |
| Which of the following media would you use to isolate Francisella tularensis: | View Page |
| Which of the following media is a selective medium for Campylobacter jejuni: | View Page |
| Which of the following two media are appropriate for Bordetella pertussis: | View Page |
| Sheep blood agar contains inhibitors to which of the following organisms: | View Page |
| Which one of the following statements about E.coli O157:H7 is false: | View Page |
| What is the best term to describe the clear areas seen around the colonies on this blood agar plate: | View Page |
| The Thayer-Martin agar plate seen in this illustration exhibits marked growth. The most likely organism found here would be: | View Page |
| The red/pink color of the colonies (E. coli) seen on this MacConkey Agar Plate is an indication of: | View Page |
| The most likely organism to be cultured on the Lowenstein-Jensen agar slant illustrated here would be: | View Page |
| The grow seen here on PPLO agar is most likely caused by: | View Page |
| The carbohydrate utilization reaction seen in the QuadFerm system shown in the picture provides a definitive identification of N. gonorrhoeae: | View Page |
| The patient was admitted to the hospital. The sputum specimen was inoculated to sheep blood agar. Based on the colony morphology seen in the accompanying photograph, the most likely identification is: | View Page |
| The name of the rapid test as illustrated in this photograph, often used to differentiate S. pneumoniae from viridans streptococci, in which a drop of 10% deoxycholate was placed on an area of growth, is: | View Page |
| The colonies shown in the blood agar (upper) and MacConkey 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 MacConkey agar rules out the following two bacterial species: | View Page |
| The bacterial species shown growing on 5% sheep blood agar was recovered from the spun sediment of a midstream urine specimen after 24 hours incubation at 35C. Each of the following tests would be useful in supporting the presumptive identification of Enterococcus species except: | View Page |
| The spot test that is helpful in separating Enterococcus species (positive as shown in the photograph) from the viridans streptococci and S. pneumoniae (both negative) is: | View Page |
| Illustrated in this photograph is a quadrant plate containing brain heart infusion agar plate supplemented with 6 ug/ml of vancomycin. The right upper quadrant was inoculated with the test strain of Enterococcus faecium. The presence of growth in the inoculated quadrant indicates resistance to vancomycin. | View Page |
| Colony Morphology The growth observed on the anaerobic blood agar plate after 48 hours incubation (see upper photograph), revealed a spreading colony. The spreading nature of the colony is better observed in the close-in photograph (lower). No growth was observed on subcultures incubated aerobically indicating that this isolate is truly an anaerobe (although aerotolerance studies would be needed for confirmation). The spreading nature of the colony and the lack of hemolysis are highly suggestive of Clostridium septicum. However, biochemical confirmation is necessary. | View Page |
| Staph on BA The photomicrograph of the surface of a 5% sheep blood agar illustrates the colonies that grew out of the foot drainage after 24 hours at 35C. They are entire, convex, smooth, and have a slight yellow pigmentation. Hemolysis is not observed. A gram stain was prepared from one of the isolated colonies. | View Page |
| Staph aureus Mannitol The ability to grow in 6.5% NaCl and to produce acid from mannitol was once considered sufficient to identify S. aureus.Although other Staphylococcus species have these characteristics, mannitol salt agar, as shown here, can still be used for epidemiologic studies in suspected cases of S. aureus outbreaks.As shown in the photograph, the presence of colonies indicates the ability to grow on 6.5% NaCl; and, the yellow pigment of the colonies indicates acid production from mannitol. | View Page |
| MRSA Screen Perhaps the most efficient means for detecting methicillin-resistant staphylococci in clinical laboratories is the use of the agar dilution screening test.Illustrated in the photograph is a Mueller-Hinton agar plate containing 6ug/ml of oxicillin, previously inoculated with a strain of Staphylococcus aureus. Oxacillin is used as a marker for methicillin resistance because it is more stable in the agar medium. Growth on this screening medium is presumptive for methicillin resistance.Thus, in the presence of growth, as shown here, a follow-up MIC test must be performed to determine the exact level of resistance. | View Page |
| MRSA Disk Test The disk diffusion test can also be used in the detection of methicillin-resistant Staphylococcus aureus.Illustrated in the photograph is the surface of a Mueller-Hinton agar plate previously inoculated with a strain of S. aureus suspected of being methicillin-resistant. Although the zone of inhibition is at the borderline for resistance (18 mm); the presence of small colonies within the zone of inhibition (yellow arrows) indicates the presence of heteroresistant strains.The interpretation here, therefore, is "methicillin-resistant" staphylococci, even though the zone diameter appears to be adequate. The detection of the heteroresistant strains indicates that MIC studies are required. | View Page |
| S. milleri Biochemicals The combination of decarboxylation of arginine (red color in the 2nd tube from left compared to the yellow color of the control to its left), the hydrolysis of esculin (black pigment in the esculin agar tube) and the reduction of nitrates to nitrites (red color in last tube on the right) are biochemical characteristics confirmatory for S. milleri (anginosus). | View Page |
| Listeria motility Listeria monocytogenes is optimally motile at 25C; and is non-motile at 35-37C.Motility may be directly assessed by observing bacterial cells with a tumbling motion in a direct mount preparation.In soft motility agar, the identification can be made by observing for a thin, umbrella-like lateral extension of growth from the stab line (see photograph). | View Page |
| Colony Morphology Photograph of the surface of blood agar after 24 hours incubation at 35C in 10% CO2, on which are growing tiny, translucent, gray colonies surrounded by a narrow zone of "soft" beta hemolysis.There was no growth on the MacConkey plate. | View Page |
| Shown in the photograph are three tubes-(1) motility agar (note subsurface flare--see arrows); (2) esculin hydrolysis (+), and (3) VP (+). The reactions illustrated here are sufficient to rule out Erysipelothrix rhusiopathiae. | View Page |
| Eikenella BAP Photograph of the surface of a 5% sheep blood agar plate after 48 hours incubation at 35 degrees C in 10% CO2.The colonies shown are small, flat, entire, dull gray, and show superficial pitting of the agar (see yellow arrows).A slight discoloration of the agar surrounding the colonies is seen.A bleach-like odor is detected.Similar growth was seen on a chocolate agar plate set up in parallel.Growth was not observed on the MacConkey plate. | View Page |
| A bacterial isolate that produces pitting of the agar and has a bleach-like odor is probably E. corrodens. Closely related species that must be ruled out include: | View Page |
| 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 diagnosis is: | View Page |
| 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: | View Page |
| The colonies shown in the upper image, obtained from a biopsy of an ulcerating skin lesion of the arm, are growing on agar slants of Sabouraud's dextrose agar. The lower image is a photomicrograph of a lactophenol blue mount made from a portion of the colony growing in the left slant. The diagnosis is: | View Page |
| One of the characteristics common to the dimorphic molds is the ability to convert the mold forms to the yeast forms by incubating subcultures in enriched media at 35°-37°C. The upper image illustrates a subculture of a mold colony suspected of being a dimorphic fungus inoculated to the surface of blood agar and incubated for 3 days at 37°C. Note that the colonies have a prickly appearance, suggesting an intermediate stage of conversion. The lower image is a lactophenol blue mount of a portion of one of the prickly colonies. This fungus can be identified as: | View Page |
| The colonies growing on the surface of this brain-heart infusion with blood agar plate were "converted" from a mold colony suspected of being Histoplasma capsulatum by incubating a subculture at 37°C for 5 days. The yeast forms that must be identified in mounts made from one of these colonies to confirm the identification are: | View Page |
| Match the names of each of the yeast species with its most likely colony morphology as seen in the images on the right. | View Page |
| Match the names of each of the yeast species listed with its corresponding appearance when grown in cornmeal agar, as seen in the images. | View Page |
| Match the names of each of the species of yeast listed with its associated phenotypic property that is helpful in establishing a species identification. | View Page |
| Match each of the microscopic structures listed in the drop-down box with the name of its corresponding yeast species on the right. | View Page |
| Arrange in sequence the steps that should be taken to make a definitive identification of Cryptococcus neoformans. | View Page |
| Match each of the fungal species listed below with the appropriate category, indicating whether or not it has the capability of producing pseudohyphae on cornmeal agar. | View Page |
| The colonies shown in this photograph were grown on Guizotia abyssinica (bird seed) agar at 30°C for 72 hours. The most likely identification is: | View Page |
| The growth of the yeast-like colonies shown in the upper image was obtained on blood agar from a skin culture only in the area overlaid by virgin olive oil. The lower image is a photomicrograph of a lactophenol blue mount made from a portion of the colony. The disease associated with this fungus is: | View Page |
| This photomicrograph is an acid-fast stained smear prepared from a yeast colony growing on ascospore agar. A helmet-shaped, red-staining, acid fast yeast cell is seen in the center of view at the tip of the arrow, against the background, blue-staining blastoconidia. The presumptive identification of Hansenula anomala was made. Predisposing conditions that may indicate that this isolate is more than a contaminant include: | View Page |
| Illustrated in this photomicrograph of a lactophenol blue preparation of a urine sediment is a cluster of yeast cells that were presumptively identified as Cryptococcus species. Further characteristics that may assist in confirming this identification are: | View Page |
| A yeast identification system gave a biotype number for an unknown isolate that did not differentiate between Candida tropicalis and Candida parapsilosis. This isolate could be identified as C. parapsilosis in a cornmeal agar preparation if it produced: | View Page |