Gram-negative

Question 1

One of the first steps in identifying an unknown bacterium

Answer 1

Gram Stain

Question 2

Appear as rods

Answer 2

Enterpbacteriaceae and Pseudomonas spp.

Question 3

Gram negative cocci

Answer 3

Nesseria spp and Moraxella catarrhalis

Question 4

Oval coccobacilli

Answer 4

Haemophilus spp, Francisella spp and Acinetobacter spp

Question 5

Large, moist and grow well on TSA with 5% sheep blood after 24hr of incubation

Answer 5

Enterobacteriaceae

Question 6

Smaller but distinct colonies after 24hr

Answer 6

Neisseria spp

Question 7

May require 48hr or more of incubation before growth is evident

Answer 7

Non fermentative gram negative rods and fastidious fermenters

Question 8

Presence of clearing of the red blood cells around the colonies (B-hemolysis) on Blood agar

Answer 8

(EP MAN) E. Coli, Pseudomonas aeruginosa, Morganella morganii, Aeromonas hydrophila, commensal Neisseria spp

Question 9

Only partial hemolysis of the cells, forming a greenish discoloration(a-hemolysis) around the colony

Answer 9

Eikenella corodens and Alcaligenes faecalis

Question 10

“Swarming” edges that can spread to cover the entire plate

Answer 10

Proteus mirabilis and Proteus vulgaris

Question 11

Bioluminescent

Answer 11

Photorhabdus spp.

Question 12

Parasite associated with Photorhabdus

Answer 12

Nematodes

Question 13

Yellow-orange pigment

Answer 13

Carotenoids

Question 14

Violet or purple

Answer 14

Violacein

Question 15

Red, maroon or yellow pigment

Answer 15

Phenazines

Question 16

True or Flase: Carotenoids, Violacein and Phenazines are water soluble?

Answer 16

True

Question 17

What are the composition of a media that detects pigment production?

Answer 17

1. ) special peptones

2. ) inc. conc. of magnesium and sulfate ion

Question 18

Pigment can also be observed in growth on TSA with?

Answer 18

Brain heart infusion agar
Loeffler’s agar
5% sheep blood agar
(BLS)

Question 19

Bacterias with yellow pigment?

Answer 19

Enterobacter spp, Chryseobacterium,
Agrobacterium spp and Phingomonas spp
(E-CAP)

Question 20

Bacterias with yellow-brown pigment?

Answer 20

Burkholderia cepacia and Burkholderia gladioli

Question 21

Bacteria with violet pigment?

Answer 21

Chromobacterium violaceum

Question 22

Bacterias with pink to red pigment?

Answer 22

Methylobacterium spp, Roseomonas spp, and some Serratia spp.
(MRS)

Question 23

Bacteria that produces pyoverdin and pyocyanin pigment?

Answer 23

Pseudomonas aeruginosa

Question 24

Water-soluble and diffusible pigment

Answer 24

Pyocyanin and Pyoverdin

Question 25

sugar that is fermented in MacConkey Agar?

Answer 25

Lactose

Question 26

Bacteria that grows in MacConkey Agar for 24hr-48hr

Answer 26

Enterobacteriaceae spp.

Question 27

Bacteria that take up to 7 days of incubation for growth to appear in MacConkey Agar?

Answer 27

Fastidious fermenters and Nonfermentative gram-negative

Question 28

Inability to grow on MacConkey Agar?

Answer 28

most Moraxella spp. and most of Neisseria spp

Question 29

Gram-neg organisms that ferment lactose and have purple colonies as the neutral red indicator changes due to production of gas

Answer 29

Klebsiella pneumoniae and Escherichia coli

Question 30

Do not ferment lactose and appear colorless or transparent on MacConkey Agar?

Answer 30

Proteus spp. and Pseudomonas spp.

Question 31

Have acid reaction with often gas production after 24 hr incubation at 35-37 degree Celsius on Triple Sugar Iron (TSI) agar

Answer 31

Enterobacteriaceae and Aeromonas

Question 32

Have weak acid reaction that may take up to 48hr to appear and will have no gas production on TSI agar

Answer 32

Fastidious fermentative gram-negative rods Eikenella Pasturella (FEP)

Question 33

No color change on TSI medium or will produce a pink, alkaline reaction as the bacteria break down the peptones in agar base

Answer 33

Pseudomonas Moraxella Nonfermentative gram-negative (PMN)

Question 34

Negative for Oxidase

Answer 34

all members of Enterobacteriaceae

Question 35

A member of enterobacteriaceae that is positive for oxidase

Answer 35

Plesiomonas shigelloides

Question 36

Positive for oxidase?

Answer 36

(CNA MVP) Campylobacter Neisseria Aeromonas Moraxella Vibrio Pseudomonas spp.

Question 37

Spp that can be distinguished from other similar non fermentatice gram-negative rods by negative oxidase reaction

Answer 37

Acinetobacter

Question 38

Reason why medium containing whole blood should not be used for catalase?

Answer 38

RBCs have catalase that can cause false positive result

Question 39

Why is Chocolate Agar used for catalase test?

Answer 39

Because RBCs have been destroyed while preparing the media

Question 40

Spp with catalase positive?

Answer 40

Moraxella spp | Fastidious fermenters

Question 41

Spp which is catalase negative

Answer 41

Kingella spp.

Question 42

What bacteria is strongly positive in catalase test when used with 30% hydrogen peroxide(superoxol)?

Answer 42

Neisseria gonorrhoeae

Question 43

Citrate Negative

Answer 43

Shigella spp. Escherichia coli Moraxella spp. (SEM)

Question 44

Citrate positive

Answer 44

many Enterobacteriaceae

Question 45

Consistently positive for citrate utilization?

Answer 45

Alcaligenes faecalis | Achromobacter xylosoxidans

Question 46

A positive citrate reaction helps distinguish ____ and _____

Answer 46

Roseomonas gilardii and Methylobacterium spp.

Question 47

Indole positive

Answer 47

E.coli Cardiobacterium hominis Chryseobacterium indologenes Nonfermentative gram-negative rods

Question 48

What will be added to Ehrlich's reagent for weakly reacting nonfermenters and fastidious organisms for Indole production?

Answer 48

1% p-dimethylaminobenzaldehyde