April 2011 Lab Practical

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WINDSOR UNIVERSITY SCHOOL OF MEDICINE

ST. KITTS

MICROBIOLOGY PRACTICALS

QUESTIONS 30 APRIL 1 2011

1.

Which of the following two dyes are used Gram staining?

A.

Mehylene blue and Congo red

B.

Nigrosin and carbolfuchsin

C. Crystal violet and safranin

D.

Crystal violet and mehylene blue

2.

The acid fast staining is an important diagnostic tool in patients who have:

A.

Pneumonia

B.

TuberculosisC.

Meningitis

D.

Diphtheria

3.

At the conclusion of alcohol decolorizing step during Gram staining procedure, Gram negative

bacteria would appear:

A.

Blue purple

B.

Red

C. Colorless

D.

Deep green

E.

None of the above

4.

All of the following are required to perform the streak plate technique for isolation purification

of bacteria EXCEPT:

A.

An inoculating wire loop

B.

A plate of suitable agar medium

C.

A culture of bacter or clinical specimen suspected to contain pathogenic bacteria

D. An electrophoresis machine

5.

A loopful of a bacterial culture is mixed in a drop of 3% hydrogen peroxide. Within a few

seconds numerous bubbles are formed. This is due to the action of which of the bacterial

enzymes?

A.

Oxidase

B.

Phosphotase

C. Catalase

D.

Coagulase



6.

The autoclave uses all the following conditions to kill microorganisms EXCEPT:

A.

A steam temperature of 121 C

B.

A time of 15 mintues

C.

A pressure of 15 lbs per square inch

D. A volume of 10 atmospheres

7.

Microscopic examination of a Gram stained smear of culture from a pus swab shows Gram

positive cocci in clusters, giving a positive test for catalase and coagulase. What is the most

likely identification?

A. Staphylococcus aureus

B.

Staphylococcus Saprophyticus

C.

Streptococcus pyogenes

8.

Microscopic examination of a mount of Inida ink mount of a culture from a case of meningitis

shows encapsulated budding yeast cells. The organism is most likely to be:

A.

Streptococcus pneumonia

B. Cryptococcus neorformans

C.

Cumbda albicans

D.

None of he above

9.

Culture of mold recovered from the scrapings and hair from inflammatory lesions on the scalp

in a 10 year old boy yields a dermatophyte forming moderately fast growing velvet to powdery

cinnamon brown colored colonies on Sabouraud dextrose agar. Microscopic examination of

lactophenol blue mounts of the culture shows rough thick walled fusiform ellipsoid septate

camrocomidia. Which is the likely species?

A.

Trichophyton mentagrophytes

B.

Trichophyton rubnum

C. Microspurum gypseum

D.

Microsporium canis

10.

Culture of mold recovered from the scrapings and hair from inflammatory lesions on the arm in

a 15-yr-old girl yields a slow growing mold with velvety to whitish powdery and granular

colonies. Microsopic examination of lactophenol blue mounts of the culture reveal septate

hyphae bearing pyirifrm to subglobose microcondida borne singly and in groups, and thin,

smooth-walled macrocoinda borne singly. Which is the likely species of dermatophyte?

A. Trcihophyton rubrum

B. Trichophyton mentagrophytes

C. Epidermophyton floccosum

D. Microsporum gypseum



11.

Which of the dimorphic fungi produces a fission yeast form in tissue and in culture as 0 degrees

Celsius in brain-heart infusion agar?

A. Penicillium marneffei

B. Histoplasma capsulatum

C. Blastomyces Dermatitidis

D. Sporothrix Schenekii

12.

A culture from a case of otitis media yields a gram negative, non-fermenting rod that is positive

for the oxidase test and produces a bluish green pigment. The organism is resistant to several

antibiotics but is susceptible to ticarcillin, piperacillin and tobramycin. The organism is likely to

be identified as:

A. Serratia marsacens

B. Staphylococcus aureus

C. Proteus mirabilis

D. Aeromonas sp

E. Pseudomonas aeruginosa

13.

In a laboratory test, a loopful of a bacterial culture is mixed with a loopful of rabbit plasma.

After about a minute, the plasma is clotted. The microbial product that is responsible for this

activity is:

A. Catalase

B. Oxidase

C. Coagulase

D. Thrombin

E. Prothrombin

14.

A laboratory medium for bacteria can be enriched by:

A. Adding ATP

B. Adding blood

C. Including salts in the medium

D. Increasing the level of potassium.

15.

Gram stain of a swab from a case of vaginitis in 32-year old pregnant female shows budding

yeast cells and occasional pseudohypae. The etiological agent is likely to be:

A.

Aspergillus

B.

Penicillium

C.

Trichosporon

D.

Canidada sp



16.

Nutrient agar is

A.

Selective media

B.

Differential media

C.

Special media

D. Basic medium

17.

Which of the following culture media is suitable for semi quantitative bacterial colony count in

urine samples:

A.

Mac Conkey agar

B.

Blood agar

C. Cled agar

D.

All of the above

18.

Media use for differentiate between Lactose Fermenting and Non Lactose Fermenting bacteria:

A.

Mac Conkey agar

B.

Cled Agar

C.

Chocolate agar

D.

Nutrient agar

19.

Addition of blood to a culture medium only allows the hemolytic bacteria that grow on the

plate to be picked out. This is an example of a:

A.

Differential media

B.

Liquid media

C.

Selective media

D.

Chemically defined media

E.

Complex media

20.

All of the following are true about agar except it:

A. Liquefies at 100 C

B.

Is a polysaccharides derived from a red algae.

C.

Facilitates obtaining pure culture

D.

Solidifies at approximately 40 C

21.

Bluish green pigment is produced by:

A. Pseudomonas

B.

Maroescemia

C.

Staphylococcus

D.

All of the above

E.

None of the above



22.

The medium generally used for caltivating dermatophytes and other fungi

A. Sabourauds dextrose agar

B.

Chocolate Agar

C.

Macconkey agar

D.

Blood agar

23.

Hemolytic activity of bacteria can be demonstrated in the following medium:

A.

Nutrient agar

B. Blood agar

C.

Mac Conkeys Agar

D.

None of the above

24.

Which of the following media is commonly used when performing the antibiotic testing.

(something Baur diffusion)

A.

Chocolate agar

B.

Hinton agar

C.

Mac Conkey agar

D.

Thayer martin agar

25.

Which is the likely organism in this image? (picture on the exam bunch of squiggly lines)

A. Streptococcus

B.

Staphylococcus

C.

Candida

D. Lacto….





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April 2011 Lab Practical