Exam B Make Up Material

Question 1

What is the purpose of lysis centrifugation in the clinical lab?

Answer 1

Lyses RBCs to increase the yield of microorganisms in primary cultures

Question 2

A bacteria is found to have the mecA gene. What is the antibiotic of choice?

Answer 2

linezolid and daptomycin

Question 3

What’s a synergistic combination of antibiotics…?

Answer 3

Beta lactams + aminoglycosides

Question 4

A patient is founds to have recurring fevers and a bacteria is found in the patient. The patient was bit by a tick 2 weeks ago. What could the bacteria be?

Answer 4

Borrelia recurrentis, It is spread by ticks. Its not burgdorferi b/c there is no bullseye rash.

Question 5

What organisms could be used for QC for OF test?

Answer 5

E. Coli for positive fermentation and Pseudomonas aeruginiosa for negative fermentation. I think Klebsiella for green b/c it is assachrolytic

Question 6

What is the reagent for ONPG?

Question 7

What is the reagent for the nitrate test?

Answer 7

sulfanilic acid (reagent A)
α-naphthylamine (Reagent B)

Question 8

What kind of pigments can pseudomonas aeruginosa produce?

Answer 8

Pyocyanin and any other pyopigments

Question 9

What is the purpose of resin in blood culture bottles?

Answer 9

To inactive antibiotics or medication in the blood of patients

Question 10

A gran negative rod is isolated from a wound. The bacteria is able to ferment lactose, oxidase positive, and TSI: A/A no gas, no H2S

Question 11

What are key differential biochemical reactions between Pseudomonas and stenotrophomonas?

Question 12

A gram negative rod is isolated from a patient’s wound. It is non glucose fermenter, and produces H2S.

Question 13

What are ideal CO2 levels for anaerobic bacteria’s?

Answer 13

5-10% CO2

Question 14

What are differentiating biochemical reactions between Aeromonas and shewanella?

Question 15

What are differentiating biochemical reactions between prevotella and porphyromonas?

Question 16

What are differentiating biochemical reactions between bacterioides and fusobacterium?

Answer 16

Bacteroides has round ends while fusobacterium has tapered ends.
Bacteroides is resistant to kanamycin and colistin. Fusobacterium is susceptible to kanamycin and colistin

Question 17

What bacteria is susceptible for SPS disc?

Answer 17

P. Anaerobius

Question 18

What are visual differences in colonies between M. Hominids and U. Urelyticus?

Answer 18

M. Hominid -> Small pinpoint colonies that are arginine positive

U. Urealyticus -> urease +, large fried egg colonies

Question 19

What syphilis tests are used to confirm infection?

Answer 19

FTA-ABS and TP-PA

Question 20

What is the purpose of D-test in the clinical lab?

Answer 20

To assess if the bacteria has an inducible clindamycin resistance due to erythromycin

Question 21

What are H2S positive bacteria genus?

Answer 21

Citrobacter, Salmonella, and proteus

Question 22

What are urease positive organisms?

Answer 22

Proteus, Klebsiella, Serratia, and Moraxella

Uncle Pete Knitted Sweaters On Monday

Question 23

What are differences between in appearance between. B. Fragility, and yersinia pestis?

Answer 23

B. Fragility - safety pin appearance due to vacuoles

Y. Pestis - bipolar staining

Question 24

What is the appearance of yersinia enterocolitica on CIN agar?

Answer 24

Bull’s eye target

Question 25

What does full purple on LIA mean about the bacteria?

Answer 25

It has lysine decarboxylase

Question 26

LIA agar with K/A mean?

Answer 26

Glucose fermentation

Question 27

What does Red slant and yellow butt mean for LIA agar?

Answer 27

Deamination of lysine which suggest Proteus and Providencia

Question 28

What are the advantages of broth dilution?

Question 29

What are disadvantages of broth dilutions?

Question 30

An in oculus on MH Kirby Bauer broth with an. Equivalent to 2 MacFarland standard. Which of the choices are true?
A. Zone too large
B. Zone too small
C. Zone is correct
D. Needs longer incubation

Answer 30

I think B. Zone too small b/c there is more bacteria than normal.

Question 31

A plate has bacteria colonies that look like bread. Crumbs. The colonies are yellow, what could this bacteria be?

Answer 31

Fusobacterium nucleatum

Question 32

A bacteria colony is found to be black pigment. What could this bacteria be?

Answer 32

Peptococcus. Niger

Question 33

Plate of bacteria colonies show pitted agar characteristic. What could this bacteria be?

Answer 33

Eikenella corrodens

Question 34

What are key biochemical reactions that differentiate prevotella and porphyromonas

Question 35

A bacteria growing on BAP is found to have yellow bacteria colonies that resemble ground glass. What bacteria could this be?

Answer 35

C. difficle

Question 36

What kind of bacteria could have molar tooth colonies they are mature?

Answer 36

Actinomyces

Question 37

What kind of bacteria could have sulfur granules?

Answer 37

Actinomyces

Question 38

A man comes into the clinic with dysuria, discharge coming out of his penis. A closer look at the discharge has WBCs but not bacteria. What bacteria could cause this?

Answer 38

Lymphogranuloma venerum. If there

Question 39

QC using Klebsiella oxytoca on an API strip test, shows all positive results except VP. What is the best course of action?
A. Return the api test reagent strips back to the manufacturer
B. Make new VP reagents and retest
C. Streak a new isolate of Klebsiella and retest
D. Report to supervisor about…

Answer 39

I think C is the correct answer. The previous colony might have been a contaminant that has the same physical characteristic as K. oxytoca. Streaking a new isolate may fix the negative VP.

Question 40

How do automated incubators determine a positive culture versus a negative culture?

Answer 40

A change in CO2 in the culture container.

Question 41

Anerobic gram negative bacteria was detected from a neck abcess. The colonies looked like bread crumbs. What are the expected biochemical test results?
A. Growth on LK laked agar
B. Positive for bile esculin
C. Susceptible to Kanamycin and colistin
D. Resistant to vancomycin and kanamycin

Answer 41

C. Susceptible to Kanamycin and colistin. The bacteria is most likely fusobacterium.

Question 42

3 Sets of blood cultures were collected and grew the following
Set #1
Aer- s. Aureus
Ana- nothing

Set #2
Aer- S. aureus and Strep
Ana- S. aureus

Set #3
Aer- S. aureus
Ana- S. aureus and Strep

Answer 42

I would go with the answer choice that has Set 2 as the answer. Streptococcus is an aerobic question. It would not make sense if strep was growing in the anaerobic culture unless it was compromised.

Question 43

Patient came in with a wound with dark pigment to it, what would the bacteria be

Question 44

What nonspecific tests are used to monitor syphilis treatment?

Answer 44

RPR and VDRL

Question 45

What media is used to culture leptospira?

Answer 45

Fletcher’s or Stuart’s media

Question 46

Gram negative, oxidase positive, catalase positive, grow on thayer martin agar, DNAse positive, and assachrolytic. The colonies look like hockey pucks and slide around on the agar. What bacteria could this be?

Answer 46

Moraxella catarhalis

Question 47

What biochemical test is used to determine if the microbe possesses tryptophanase?

Answer 47

Indole test.

Question 48

What is the reagent used in the indole test?

Answer 48

Kovac’s reagent - consisting of isoamyl alcohol, para-dimethylaminobenzaldehyde, and concentrated hydrochloric acid.

Question 49

In the citrate test, what is used for carbon source and what is used for nitrogen source?

Answer 49

Carbon source - Sodium citrate
Nitrogen source - Inorganic ammonium salts

Question 50

What is the reagent used in the MUG test?

Answer 50

A disk containing 4-methylumbelliferyl-𝝱-D-glucuronide (MUG) to detect the presence of Beta - glucuronidase

Question 51

What biochemical test is used to detect the presence of Beta - galactosidase enzyme in the microbe?

Answer 51

ONPG test - a positive is yellow. It uses ONPG (o-nitrophenyl-𝝱-D-galactopyranoside) that is hydrolyzed in the presence of Beta galactosidase into galactose and o-nitrophenol (both yellow colored product).

Question 52

What is the ideal number of blood cultures for bacteremia and endocarditis?

Answer 52

3 - 5 blood cultures in 24 hours required for a correct diagnosis

Question 53

What organisms may be encountered as skin contaminants at a venipuncture site?

Answer 53

S. epidermidis, Bacillus spp., and Propionibacterium acnes

Question 54

What are 4 factors in visual observation that indicates bacterial growth?

Answer 54

Turbidity, hemolysis, gas production, and color change

Question 55

What is the ideal number of blood cultures and time interval between blood culture collections?

Answer 55

At least two cultures from different sites with at least 30 minutes interval during a 24-48 hours

Question 56

What are the purpose of resins in blood cultures?

Answer 56

Resins are added to reduce the activities of several antibiotics

Question 57

What gene in Klebsiella pneumoniae is thought to be responsible for producing beta lactamase that inactivates ampicillin?

Answer 57

Bla (SHV) gene

Question 58

Why doesn’t vancomycin work on lactobacilli and leuconostoc spp.?

Answer 58

They lack the appropriate cell wall precursor target

Question 59

If a bacteria has the Erm gene what antibiotic resistance would they have?

Answer 59

Clindamycin resistance

Question 60

If a bacteria has rpoB gene what antibiotic resistance would they have?

Answer 60

Rifampin resistance

Question 61

What bacteria does rifampin increase mutations in?

Answer 61

M. tuberculosis which are spontaneous mutations in the rpoB gene encoding beta subunit of RNA polymerase

Question 62

What is the Nagler’s test?

Answer 62

Test to identify organisms that have lecithinases for example C. perfringens.

Question 63

What bacterias would be good QC for IMVIC tests?

Answer 63

E. coli, & morganella -> + / + / = / =
Klebsiella & Eneterobacter -> = / = / + / +
Note: Not K. oxytoca

Question 64

What two antibiotics are synergistic?

Answer 64

Beta lactams and aminoglycosides