Bacteriology - MICRO LAB

Question 1

Way differentiate gram-positive cocci Staph versus strep?

Answer 1

Staph is catalase +

Strep is Catalase (-)

Question 2

Way to differentiate Step epidermidis from saprophyticus?

Answer 2

Novobicin test.

saprophyticus is resistant to novobicin.

Question 3

What are the 2 beta hemolytic strep?

Answer 3

Strep pyogens [GAS]

S. agalactiae [GBS]

Question 4

How are GAS and GBS differentiated?

Answer 4

GAS: Bacitracin sensitive
GBS: Resistant

Question 5

What list the GPC, catalase negative, alpha and gamma hemolytic [4]

Answer 5

1. S. pneumo
2. Viridans group strep
3. Enterococcus
4. S. bovis

Question 6

What is the purpose of the optochin test?

Answer 6

Catalase negative alpha/gamma GPC:

–> Strep pneumo is sensitive to optochin and will be killed, removing it as a possibility

Question 7

What is the purpose of the bile esculin test?

Answer 7

Catalase negative alpha/gamma GPC:

–> Only GDS and Enterococcus are positive, excludes viridans strep and strep pneumo.

Question 8

What is the point of the 6.5% NaCl growth test?

Answer 8

Catalase negative alpha/gamma, bile esculin + GPC:

–> Only Enterococcus species can grow, inhibits strep bovis [GDS]

Question 9

What is the purpose of the tellurite test?

Answer 9

Catalase negative alpha/gamma, bile esculin +, 6.5% NaCl growth test + GPC:
–> Differentiates E. faecalis from E. faecium.
E. faecalis reduces tellurite to tellium, turing the media black.
E. faecium does not.

Question 10

Three medically important gram negative cocci?

Answer 10

1. Moraxella catarrhalis
2. N. gonorrhoeae
3. N. meningitidis

Question 11

What does M. catarrhalis ferment?

Answer 11

Nothing

Question 12

What does N. gonorrhoeae ferment?

Answer 12

Glucose

Question 13

What does N. meningitidis ferment?

Answer 13

Maltose and glucose

Question 14

Which GNDC can reduce nitrates?

Answer 14

M. catarrhalis

Question 15

Which GNDC is oxidase +?

Answer 15

ALL 3

–> Positive means cytochrome c is present

Question 16

Which GPR are spore forming? [3]

Answer 16

Clostridium
B. cereus
B. anthacis

Question 17

How is bacillus separated from clostridium species?

Answer 17

Bacillus is aerobic

Clostridium is anaerobic

Question 18

How is B. anthacis separated from B. cereus? [3]

Answer 18

GBR, spore forming, aerobic

• -> B. anthacis is penicillin sensitive, B. cereus is NOT.
• -> B. cereus is MOTILE, anthacis is not
• -> B. cereus is beta hemolytic, anthracis is not

Question 19

What are the non-spore forming GPR?

Answer 19

A. haemolyticum
Corynebacterium
E. rhusiopathiae
G. vaginalis
Lactobacillus
Listeria
Nocardia

Question 20

Which GPR are beta hemolytic? [3]

Answer 20

A. haemolyticum
B. cereus
L. monocytogenes

Question 21

Which GPR are catalase positive? [3]

Answer 21

Bacillus
C. diphtheriae
L. monocytogenes

Question 22

Which GPR are catalase negative [3]

Answer 22

A. haemolyticum
Erysipelothrix
Lactobacillus

Question 23

How should C. diphtheriae be evaluated?
Morphology on gram stain?
Spore forming?
Motility?
Medium to enhance growth? [2]
Special features on stain?

Answer 23

GPR
+ Catalase
NON-SPORE forming
NON-Motile
–> Loffler’s medium inhibits other throat flora and enhances typical metachromasia [methylene blue stain will highlight this
–> Tellurite plate highlights reduction of tellurium salt

Question 24

Gram stain shows GPR with large boxcar appearance. +/- spores. Ddx?

Answer 24

• Clostridium

- Bacillus

Question 25

GPR with small palisading arrangement on gram stain. Ddx? [3]

Answer 25

Corynebacterium species Arcanobacterium hemolyticum Listeria monocytogenes

Question 26

What is a clostidium species that will stain GRAM NEGATIVE ROD?

Answer 26

Clostridium tertium

Question 27

What are the biochemical characteristics of ALL GRN that are enterobacteriaceae? - -> Catalase? - -> Oxidase? - -> Nitrate reduction? - -> Glucose fermentation?

Answer 27

1. Catalase + 2. Oxidase - 3. Nitrate reducers 4. Glucose fermenters

Question 28

List all enterobacteriaceae [13]

Answer 28

1. Escherichia 2. Klebsiella 3. Hafnia 4. Proteus 5. Salmonella 6. Serratia 7. Shigella 8. Yersinia 9. Providencia 10. Enterobacter 11. Morganella 12. Citrobacter 13. Edwardsiella

Question 29

List the GRN that are NOT enterobacteriaceae that ferment lactose. [4]

Answer 29

1. Aeromonas 2. Pasteurella 3. Plesiomonas 4. Vibrio

Question 30

List the GRN that are NOT enterobacteriaceae that do NOT ferment glucose. [6]

Answer 30

``` Acinetobacter Alcaligenes Burkholderia Flavobacterium Pseudomonas Stenotrophomonas ```

Question 31

List the GRN that are NOT enterobacteriaceae that do DO ferment glucose. [4]

Answer 31

Aeromonas Pasteurella Plesiomonas Vibrio

Question 32

Which GRN produce H2S? [4]

Answer 32

Citrobacter freundii Edwardsiella tarda Proteus [both vulgaris and mirabelis] Salmonella

Question 33

Which GRN ferment lactose? [5]

Answer 33

``` E. coli Enterobacter aerogens, cloacae Citrobacter [50%] Vibrio vulnificus Klebsiella pneumoniae ```

Question 34

Which GRN are oxidase positive? [12]

Answer 34

``` NOTE: NO enterobacteraciae are oxidase positive. Aeromonas Plesiomonas Pseudomonas Alcaligenes Burkholderia Campylobavter jejuni Flaobacterium H. pylori Kingella Pasteurella Vibrio cholerae, parahaemolyticus ```

Question 35

Which GRN that are NON-enterobacteraciae are oxidase negative?

Answer 35

NOTE: ALL enterobacteraciae are oxidase negative. Acinetobacter Klebsiella pneumonia Stenotrophomonas

Question 36

Which enterobacteraciae are indole positive? [4]

Answer 36

E. coli P. vulgaris Providencia Morganella

Question 37

Which non-enterobacteraciae are indole positive? [5]

Answer 37

``` K. oxytoca Vibrio Aeromonas Plesiomonas Pasteurella ```

Question 38

Which enterobacteraciae are indole negative? [4]

Answer 38

Salmonella Enterobacter Serratia P. mirabilis

Question 39

Which non-enterobacteraciae are indole negative?

Answer 39

Klebsiella | Pseudmonas

Question 40

What culture media is used for pertussis?

Answer 40

Bordet-Gengou [previous] | Regan-Lowe [current]

Question 41

Describe stenotrophomonas resistance pattern

Answer 41

Resistant to the following routinely... 1. Pencillins 2. Cephalosporins 3. Aminoglycosides 4. Carbapenems

Question 42

Treatment of choice for steno?

Answer 42

Bactrim