FA Gram Neg Lab Algorithm

Question 1

Gram neg, oxidase +, comma-shaped (3 bugs)

Answer 1

Campylobacter jejuni,
Vibrio cholerae,
Helicobacter pylori

Question 2

Gram neg, oxidase +, comma-shaped, grows at 42 degrees C

Answer 2

Campylobacter jejuni

Question 3

Gram neg, oxidase +, comma-shaped, grows in alkaline media

Answer 3

Vibrio cholerae

Question 4

Gram neg, oxidase +, comma-shaped, produces urease

Answer 4

H pyloir

Question 5

Lactose fermenting gram - rods

Answer 5

Klebsiella, E coli, Enterobacter, Cirbobacter, Serratia

Question 6

Fast lactose fermentors (gram - rods)

Answer 6

Klebsiella, E coli, Enterobacter

Question 7

Slow lactose fermentors (gram - rods)

Answer 7

Citrobacter, Serrati

Question 8

Gram - rods, lactose nonfermentor, oxidase NEG

Answer 8

Shigella,
Salmonella
Proteus
Yersinia

Question 9

Gram - rods, lactose nonfermentor, oxidase POS

Answer 9

Pseudomonas

Question 10

Lactose fermenting enteric bacteria grow what color colonies on MacConkey agar?

Answer 10

PINK!

Question 11

what bugs are lactose fermentors? test with maConKEE’S agar

Answer 11

citrobacter, klebsiella, e coli, enterobacter, serratia

Question 12

How does e coli ferment lactose?

Answer 12

produces beta-galactosidase, which breaks down lactose into glucose and galactose

Question 13

lactose fermentors grow as purple/black colonies on what kind of agar?

Answer 13

EMB

Question 14

On EMB, what do e coli colonies look like?

Answer 14

purple colonies with a green sheen

Question 15

Why are gram negs resistant to penicillin G and vancomycin?

Answer 15

the gram neg outer membrane lair inhibits entry of penicillin G and vanco (but may allow ampicillin or amoxicillin)

Question 16

Gram neg coccoid rods

Answer 16

H influenzae,
Pasteurella
Brucella
Bordetella pertussis

Question 17

Gram neg coccoid rod plus factor V and X requirement

Answer 17

H influenzae

Question 18

gram neg coccoid plus animal bite

Answer 18

Pasteurella

Question 19

Gram neg diplococci

Answer 19

N meningitidis or N gonorrhoeae

Question 20

how do tell neisseria apart?

Answer 20

maltose (meningitidis ferments; gonorrhoeae does not)