Bacteriology-Methods

Question 1

What bacteria grow best at 25-30C? (2)

Answer 1

• Yersinia entercolitica

- Psuedomas spp.

Question 2

Gram Stain Morphology:

-Pyogenic streptoccoci

Answer 2

Gram Positive Cocci

-Pairs/Short chains

Question 3

Indole Test use/function.

Answer 3

Identification of E. coli (indole Positive)

*not unique to E. coli

Question 4

What biochemical test is used to identify Group B pyogenic strep and Listeria monocytogenes?

Answer 4

CAMP Test

*Both produce CAMP factor

Question 5

Gram Stain - Gram Negative features:

• Peptidoglycan*
• Outer membrane

*Staining characteristic

Answer 5

• Thin peptidoglycan cell wall*
• Outer membrane present

*Lose crystal violet/Iodine during decoloarization – Visualized w/ Red Safranin counterstain

Question 6

Hippurate Hydrolysis Test is used for the presumptive identification of which organisms? (5)

Answer 6

• Campylobacter jejuni
• LIsteria monocytogenes
• Strep agalactiae
• Gardnerella vaginalis
• Legionella pneumophila

*All are POSITIVE

Question 7

Oxidase Positive Organisms (7)

Answer 7

• Neisseria spp.
• Moraxella
• Pseudomonas
• Legionella
• Campylobacter*
• Vibrio*
• Helicobacter*

*Curved Gram Negative RODS

Question 8

Gram Stain Morphology:

-Campylobacter

Answer 8

Gram Negative Rods

• Thin, Curved
• S-shaped, Seagull/Corkscrew

Question 9

Oxidase Negative Organism.

Answer 9

Enterobacteriaceae

Question 10

What selective media is used for recovery of Neisseria spp. from nonsterile sites?

Answer 10

Thayer-Martin medium

Question 11

Which organisms don’t grow on Sheep blood agar? (3)

Answer 11

• N. gonorrhea
• H. influenzae
• Legionella

Question 12

Gram Stain Morphology:

-Staphylococci

Answer 12

Gram Positive Cocci

-Grapelike clusters

Question 13

Novobiocin Susceptibility testUse/Function.

Answer 13

S. saprophyticus (Novobiacin Resistent) Vs. other coagulase Negative staphylococci
-S. epidermidis (Novobiacin Susceptible)

Question 14

What selective media is used for recovery of Yersinia spp.?

Answer 14

Cefsulodin-Irgasan-Novobiocin agar

CIN

Question 15

Growth in Lysozyme containing broth medium is indicative of what bacteria?

Answer 15

Nocardia

Question 16

Oxidase Test use/function.

Answer 16

Initial classification of Gram Negatives

Question 17

What medium is used to recover Legionella spp.?

Answer 17

Buffered Charcoal Yeast Extract agar

BCYE

Question 18

Coagulase Test Use/Function.

Answer 18

S. aureus (Coagulase Positive) Vs. other Staphylococci (Coagulase Negative)

*should always be confirmed using the tube test

Question 19

Gram Stain Morphology:

-Vibrio spp.

Answer 19

Gram Negative Rods

• Curved, Comma-shaped
• Short rods

Question 20

Gram Stain Morphology:

-Yersinia pestis

Answer 20

Gram Negative Rods

-Bipolar staining (“Closed Safety-Pin”)

Question 21

Gram Stain Morphology:

-Nonpyogenic streptococci

Answer 21

Gram Positive Cocci

-Long chains

Question 22

Gram Stain - Gram Positive features:

• Peptidoglycan
• Outer membrane

*Staining characteristic

Answer 22

• THICK peptidoglycan cell wall*
• NO outer membrane

*Retains purple crystal violet/Iodine stain during the decolarization step (alcohol)

Question 23

Catalase Test Use/Function.

Answer 23

Gram Positive Cocci

• Staphylococci - Catalase Positive
• Streptococci/Enterococci - Catalase Negative

Question 24

Why don’t Mycobacteria stain well with Gram Stain?

Answer 24

Mycolic Acids in Peptidoglycan Cell wall

-Hydrophobic-Repels Crystal violet/Iodine

Question 25

PYR tests use/function.

Answer 25

Identifies Group A pyogenic streptococci and Enterococcus spp. (Positive Test - Red color change)

Question 26

Which body sites normally harbor indigenous Anaerobic flora (and should not be cultured for anearobes)? (5)

Answer 26

- Stool - Skin - Oropharynx - Vagina - Urethra

Question 27

What selective media inhibits growth of Gram Positive bacteria and many Enterics? -What does grow?

Answer 27

Selenite Broth | -Samonella

Question 28

Gram Stain Morphology: | -Neisseria spp.

Answer 28

Gram Negative Diplocci | -Coffee Bean shaped

Question 29

Listeria monocytogenes - Temperature characteristics.

Answer 29

37C - Optimal growth 25C - Shows motility 4C - Able to multiply

Question 30

Optochin Susceptibility test (P disk) Use/Function.

Answer 30

S. pneumoniae (Optocin Susceptible*) vs other alpha-hemolytic Streptococci -Viridans strep (Optocin Resistent) *Shows Clearing

Question 31

Besides Staphylococci, what other bacteria are Catalase Positive? (3)

Answer 31

- Campylobacter spp. - Listeria spp. - Bacillus spp.

Question 32

Gram Stain Morphology: | -S. pneumoniae

Answer 32

Gram Positive Diplocci | -Lancet shaped

Question 33

Acid-Fast Stain principle.

Answer 33

Uses Heat and/or Phenol to allow a Fuchsin dye to penetrate the Hydrophobic barrier -Stains Mycolic Acids in cell wall

Question 34

Gram Stain Morphology: | -Enterococcus

Answer 34

Gram Positive Diplocci

Question 35

Bile Esculin Test Use/Function.

Answer 35

Identifies Enterococci and Group D strep (S. bovis)

Question 36

What selective media is used for recovery of Vibrio spp.?

Answer 36

Thiosulfate-Citrate-Bile Salts-Sucrose agar | TCBS

Question 37

Rapid Urease Test use/function.

Answer 37

Proteus spp. and H. pylori identification -Urease Positive (Red/Pink coloration)

Question 38

Gram Stain Morphology: | -Legionella

Answer 38

Gram invisible in primary smear

Question 39

Campylobacter spp. grows best at what temperature?

Answer 39

42C