Clinical Pathology(Micro)

Front 1

Which of the following dematiaceous molds is responsible for chromoblastomycosis?
A. Fonseca
B. Phialophora
C. Cladosporiom
D. Wangiella
E. Exophiala

Back 1

E. A, B, C.
Chromoblastomycosis is a cutaneous fungal infection with the “copper penny” sclerotic or Medlar bodies that represent pigmented subcutaneous septated yeast forms

Front 2

Which of the following dermatophytes can be identified with its “birds on a wire” microconidia?
A. Microsporidium canis
B. Trichophyton rubrum
C. Epidermophyton floccosum
D. Trichophyton mentagrophytes
E. Trichophyton tonsurans

Back 2

B. T.
The Trichophyton spp have microconidia and, of them, each has unique morphological features. T. rubrum has “birds on a wire” microconidia spaced along hyphae; T.
tonsurans has widely variable microconidia, while T. mentagrophytes has grape-like clusters and occasional spiral hyphae.
QCCP2, Dermatophytes

Front 3

What organism is the most common cause of onychomycosis?
A. Epidermophyton floccosum
B. Trichophyton rubrum
C. Trichophyton mentagrophytes
D. Microsporum canis
E. Microsporum gypseum

Back 3

B. T.
The Trichophyton spp, especially T. rubrum, cause the majority of cases of onychomycosis. Individuals with HIV and diabetes are at an increased risk for onychomycosis. In
addition, it is important to note that other fungi, such as Candida, can cause onychomycosis.
QCCP2, Dermatophytes

Front 4

Which of the following organisms is characterized by blue-green colonies with a white apron?
A. Aspergillus terreus
B. A. niger
C. A. fumigatus
D. A. flavus
E. Penicillium marneffei

Back 4

C. A.
Each of the Aspergillus spp has a distinct appearance on plates. A. fumigatus is blue-green, A. terreus has a cinnamon-buff colony, A. niger has a black colony, and A.
flavus has a brown colony with lateral striations.
QCCP2, Aspergillus

Front 5

Which of the following organisms is characterized by two rows of phialides on the conidia?
A. A. terreus
B. A. niger
C. A. fumigatus
D. A. flavus
E. P. marneffei

Back 5

A. A.
Just like the discrete gross appearance on plates, each of the Aspergillus spp can be speciated by the appearance of the conidia. A. terreus has 2 rows of phialides. A. niger
has black circumferential phialides. A. fumigatus has a single row of phialides. A. flavus has a circumferential row of phialides (a “flavorful lollipop”). P. marneffei looks like
A. fumigatus but lacks the swollen vesicle at the base of the phialides that all the members of Aspergillus have.
QCCP2, Aspergillus

Front 6

Which species is responsible for the majority of cases of aspergilloma and allergic bronchopulmonary aspergillosis?
A. A. flavus
B. A. fumigatus
C. A. niger
D. A. terreus
E. P. marneffei

Back 6

B. A.
There are 3 principle pulmonary diseases caused by Aspergillus spp, primarily A. fumigatus: Aspergilloma, a fungal ball that grows in the site of a pre-existing cavitary
lesion; Allergic bronchopulmonary aspergillosis, an exaggerated allergic response to noninvasive Aspergillus colonization that's seen mostly in patients with cystic fibrosis;
and finally, invasive aspergillosis, a vascular-invasive disease seen mostly in the immunocompromised.
QCCP2, Aspergillus

Front 7

Which species of Aspergillus is most commonly seen as otitis externa?
A. A. flavus
B. A. fumigatus
C. A. niger
D. A. terreus
E. P. marneffei

Back 7

C. A.
QCCP2, Aspergillus

Front 8

All of the following hyalinohyphomyces have conidia that occur in clusters, except:
A. Acremonium
B. Penicillium
C. Gliocladium
D. Fusarium
E. all of the above occur in clusters

Back 8

B. P .
If anything called for a mnemonic, it would be all these genera of hyaline molds - a “GAF” is a tool to grab things and hold them together in a cluster. The organisms with
clustered conidia are Gliocladium, Acremonium, and Fusarium. The branching chain conidia are a further reach - imagine looking through a pay telescope to see a pen
hanging from a chain on a tree branch. Interpretation - the branching chain conidia are Penicillium, Paecilomyces, and Scopulariopsis. All the rest occur singly -
Scedosporium, Beuveria, Sepedonium, and Chrysosporium.
QCCP2, Hyalinohyphomyces

Front 9

Which organism is the cause of adiaspiromycosis?
A. Fusarium
B. Chrysosporium
C. Beuveria
D. Paecilomyces
E. Gliocladium

Back 9

B. C.
Adiaspiromycosis is a benign granulomatous infection with characteristic large thick-walled spherules.
QCCP2, Conidia occurring singly

Front 10

Which of the following fungal organisms is a major concern as an opportunistic infection in burn victims?
A. Gliosporium
B. Paecilomyces
C. Scopulariopsis
D. Scedosporium
E. Fusarium

Back 10

E. F.
In addition to the myriad of infections including a disseminated infection in immunocompromised hosts, Fusarium can cause infections in burn victims, pulmonary infections,
skin infections, and fungemia.
QCCP2, Fusarium

Front 11

What is the most common cause of eumycotic mycetoma in the U.S.?
A. Fusarium
B. Scopulariopsis
C. Acremonium
D. Scedosporium
E. Paecilomyces

Back 11

D. S .
It is also a common cause of disseminated infection in near-drowning victims and infections related to penetrating trauma.
QCCP2, Hyalinohyphomyces

Front 12

All of the following are causes of eumycotic mycetoma, except:
A. Madurella
B. Actinomyces
C. Scedosporium
D. Wangiella
E. Exophiala

Back 12

B. A.
Mycetomas, or deep subcutaneous infections, can be categorized as either true (eumycotic - caused by fungus) or actinomycotic (caused by non-fungal organisms). All of
the choices presented, with the exception of Actinomyces, are fungal, or eumycotic, causes of mycetoma. The bacterial causes also can include Streptomyces and Nocardia.
QCCP2, Mycetoma

Front 13

Which of the following zygomycetes has sporangiophores that arise between rhizoids?
A. Rhizopus
B. Absidia
C. Mucormycosis
D. Cunninghamella
E. Circinella

Back 13

B. A.
Absidia and Rhizopus are the only zygomycetes that produce rhizoids or little rootlets from their hyphae. While the rhizoids in Rhizopus lie directly below the
sporangiophores, those of Absidia are offset.
QCCP2, Zygomyces

Front 14

Under what conditions must the germ tube test be run in order to identify Candida albicans?
A. suspended in broth, incubated 2 hours at 37°C
B. suspended in serum, incubated 24 hours at 37°C
C. suspended in broth, incubated 2 hours at 32°C
D. suspended in serum, incubated 2 hours at 37°C
E. suspended in broth, incubated 24 hours at 37°C

Back 14

D. suspended in serum, incubated 2 hours at 37°C.
It's actually important to understand the conditions under which the germ tube test is performed. The reason is that overincubation will greatly decrease the nearly 100%
specificity that the assay has for Candida albicans. Unlike the pseudohyphae that Candida can form in tissue, the germ tube is a true hypha (there is no “pinch” between the
germ tube and the mold).
QCCP2, The germ tube test

Front 15

Which fungal organism is urease (+) and phenol oxidase (+)?
A. Cryptococcus neoformans
B. Malassezia furfur
C. Rhodotorula
D. Candida krusei
E. Trichophyton mentagrophytes

Back 15

A. C.
All of the organisms mentioned, with the exception of Malassezia, are urease positive, but Cryptococcus is the only one that is also phenol oxidase positive. The presence of
phenol oxidase can be demonstrated on bird (Niger) seed agar where the phenol oxidase will convert the caffeic acid in the agar into melanin pigment, yielding the
characteristic brown/black pigment.
QCCP2, Yeast identification

Front 16

Which of the following organisms requires the overlay of olive oil in order to culture?
A. Cryptococcus
B. Malassezia
C. Rhodotorula
D. Candida
E. Trichophyton

Back 16

B. M.
Malassezia furfur is the cause of tinea versicolor, a skin infection usually found on greasy back skin, and is also associated with total parenteral nutrition (lipid-rich) line
infections. Malassezia requires a source of long-chain fatty acids to grow in culture. An olive oil overlay provides the required fatty acids.
QCCP2, Yeast identification

Front 17

Which of the following stains the capsule of Cryptococcus?
A. mucicarmine
B. Fontana-Masson
C. Alcian blue
D. India ink
E. GMS

Back 17

B. Fontana-Masson.
Remember, the phenol oxidase converts caffeic acid to melanin, which is what Fontana-Masson stains. The polysaccharides in the thick capsule of Cryptococcus can be
stained with mucicarmine or Alcian blue. India ink works by forming a white negative space of the organism against a black-stained background.
QCCP2, Cryptococcus

Front 18

Which of the following organisms causes infections associated with penetrating trauma and is in a class totally by itself?
A. Sporothrix
B. Fusarium
C. Prototheca
D. Rhodotorula
E. Malassezia

Back 18

C. P .
Prototheca wickerhamii is the only known algal cause of human infections. Most commonly, the infection takes the form of olecranon bursitis or a cutaneous skin infection.
The organism is said to resemble soccer balls or hub caps, referring to the morulated appearance. The organism is associated with exposure to water and dolphins.
QCCP2, Prothecosis

Front 19

What is the optimal specimen collection for bacterial blood culture?
A. 2 samples, each with more than 20 mL of blood
B. 1 sample of 5 mL blood
C. 3 samples with 5 mL blood each
D. 5 samples with 5 mL blood each
E. 3 samples with more than 10 mL blood each

Back 19

E. 3 samples with more than 10mL each.
Preferably, the samples should be collected within 24 hours and, if possible, preceding or coincident with a febrile episode. Having less than three samples decreases
sensitivity and having more doesn't improve sensitivity.
QCCP2, Bacteriology laboratory methods

Front 20

Which of the following specimens is routinely quantitatively cultured?
A. blood
B. urine
C. stool
D. sputum
E. CSF

Back 20

B. urine.
QCCP2, Laboratory Methods,specimens

Front 21

Which one of the following bacterium/additional stain pairs is incorrect?
A. H. influenzae in CSF/methylene blue
B. Legionella/GMS
C. spirochetes/dark field microscopy
D. C. diphtheriae/Loeffler methylene blue
E. Nocardia/modified acid fast

Back 21

B. L /GMS.
Several bacterial species are notable for the special requirements they have for growth or identification. All of the mentioned choices are correct except Legionella, which is
best visualized with a Dieterle stain rather than GMS.
QCCP2, T3.27, Additional bacterial stains

Front 22

In a gram stain, which compound stains the bacterial cell wall peptidoglycan?
A. iodine
B. safranin
C. decolorant
D. crystal violet
E. no compound; staining is an artifact of heat fixation

Back 22

D. crystal violet.
The crystal violet in a gram stain is applied after heat fixation (which gets the bugs to stick to the slide). Crystal violet stains the peptidoglycans of the bacterial cell wall.
After that, iodine is applied as a mordant to enhance the crystal violet staining. This is followed by decolorization where gram-positive organisms retain the violet due to
their thick cell wall and gram negatives lose the violet stain. Finally, safranin is added to stain the decolorized gram-negative organisms.
QCCP2, Direct examinatio

Front 23

What is the principal difference between the Ziehl-Neelsen acid-fast stain technique with Kinyoun acid-fast stain technique?
A. the length that the organisms are stained
B. the type of dye that is used
C. Kinyoun uses a weaker acid (sulfuric acid) rather than HCl
D. Kinyoun uses auramine-rhodamine instead of carbolfuschin as a stain
E. whether or not heat is used to fix slides

Back 23

E. whether or not heat is used to fix slides.
Acid-fast organisms are defined as those that retain carbolfuschin stain despite acid decolorization. That makes choices B and D wrong. The Fite technique differs from
Kinyoun and Ziehl-Neelsen by using a weaker acid to decolorize, and thereby stains “weakly” acid-fast organisms, such as Nocardia. The only difference between Ziehl-
Neelsen and Kinyoun stains is the type of fixation - ZN uses heat, Kinyoun does not.
QCCP2, Acid-fast stains

Front 24

Nearly all pathogenic bacteria grow on blood agar plates with the notable exception of which of the following:
A. H. influenzae
B. S. aureus
C. E. coli
D. Serratia marascesens
E. group A Strep

Back 24

A. H.
Blood agar is a non-selective media used often as the initial growth media from which colonies can be subcultured onto selective media for identification. An exception is
Haemophilus influenzae, which requires factors X (hemin) and V (NAD) that is present only when the RBCs are lysed. Therefore, to grow H. influenzae chocolate (lysed
RBC) agar or with a streak of Staphylococcus to provide the required factors.
QCCP2, Culture media

Front 25

Which specialized media is specifically used for the culture of Legionella?
A. Thayer-Martin
B. buffered charcoal yeast extract (BCYE)
C. chocolate agar
D. eosin methylene blue agar
E. MacConkey agar

Back 25

B. buffered charcoal yeast extract (BCYE).There are a number of specialized media utilized for the isolation of specific organisms. BCYE is for Legionella (I remember a “legion of bicycles”), Thayer-Martin for the
growth of Neisseria, MacConkey for gram negatives, chocolate agar for Haemophilus. Eosin methylene blue is similar to MacConkey.
QCCP2, Culture media

Front 26

What color do lactose non-fermenters appear as on MacConkey agar?
A. red
B. white
C. green
D. pink
E. black

Back 26

D. pink.
MacConkey agar is both selective for gram-negative organisms and differential for lactose fermenters v. non-lactose fermenters. The lactose non-fermenters appear as light
pink colonies, and include organisms such as Pseudomonas, Serratia, and Burkholderia.
QCCP2, Culture media

Front 27

What accounts for the high selectivity of Salmonella-Shigella agar?
A. low salt
B. high bile salt and sodium citrate
C. high growth temperature
D. inhibitory aniline dye
E. charcoal

Back 27

B. high bile salt and sodium citrate.
The selective nature of SS agar is due to the high bile salt and sodium citrate, but also to the lack of any carbohydrate except lactose, so that only lactose-fermenting
gram-negative organisms can grow. Shigella and Salmonella are distinguished as colorless colonies, whereas other gram-negative fermenters are usually red. Finally,
Salmonella is distinguished from Shigella by the presence of a black center in the otherwise clear colony.

Front 28

Which of the following media is utilized to grow Bordetella spp?
A. Regan-Lowe media
B. Bordet-Gengeou
C. CCF agar
D. A & B
E. A, B, C

Back 28

D. A & B.
CCF, or cycloserine-cefoxitin fructose-egg yolk agar, is a fairly selective medium for growing Clostridium difficile, which is a dying practice due to the high specificity and
sensitivity of immunologic testing for toxins A and B.
QCCP2, T3.29

Front 29

Which of the following organisms grows optimally at 42°C?
A. Pseudomonas
B. Listeria
C. Mycobacterium marinum
D. Campylobacter
E. Salmonella

Back 29

D. C.
Pseudomonas and Mycobacterium marinum prefer cooler temperatures (25°-30°C) while Campylobacter likes it warm (42°C). Most others grow best at body temperature,
including Listeria. The characteristic tumbling motility of Listeria, however, is best observed at 25°C.
QCCP2, Culture temperature

Front 30

Clumping of bacteria on the surface of a slide with the addition of rabbit serum describes which of the following?
A. a positive furazolidone test
B. a positive bound coagulase test
C. a positive free coagulase test
D. a negative catalase
E. a negative free coagulase test

Back 30

B. a positive bound coagulase test.
The description of the test sounds like coagulation, things sticking together. Rabbit serum provides the fibrinogen that bound coagulase converts to fibrin. A more sensitive
and time-consuming test is the tube test for free coagulase, which should be performed whenever the slide or bound test is negative. It is important to examine the test
tube at both 4 hours and 20 hours (but only if negative at 4 hours). Some strains break down clots with time (false negative at 20 hours), or some other strains take longer
to make clots (false negative at 4 hours).
QCCP2, Coagulase