LAB 6 - Fastidious Gram Negative Bacilli and Candida

Question 1

TSI sick yellow

Answer 1

Listeria
Pasteurella multocida
Yersinia

Question 2

B. pertussis media

Answer 2

Regan Lowe (mercury drop or split pearl)
DFA + PCR +

Question 3

Besides C. albicans, what other Candida is germ tube pos?

Answer 3

C. dublinensis

Question 4

T or F. H. influenzae is part of the normal flora of the upper respiratory tract

Answer 4

T

Question 5

What is H. influenzae associated?

Answer 5

meningitis
epiglottitis
pneumonia
respiratory tract infections
cellulitis
conjunctivitis

Question 6

H. parainfluenzae

Answer 6

• endocarditis
• normal bacterial flora in resp tract

Question 7

H. ducreyi

Answer 7

• sexually transmitted disease
• chancroid
• prevalent in more tropical areas

Question 8

H. haemolyticus and parahaemolyticus

Answer 8

usually nonpathogenic

Question 9

appropriate specimens for Haemophilus

Answer 9

• blood
• sputum
• CSF
• conjunctival and genital ulcer swabs

Question 10

Haemophilus sp. air requirements

Answer 10

facultative capnophilic; mousy odor

Question 11

X factor vs V factor

Answer 11

X = hemin
V = NAD

Question 12

T or F. sheep blood does not support Haemophilus sp.

Answer 12

T, rabbit and horse blood do
- sheep blood has NADase; heating sheep blood destroys this, releases hemin (which Haemophilus also needs)

Question 13

ALA test

Answer 13

• porphyrin or delta-aminolevulinic acid (ALA) test
• determines X factor requirement (ability of organism to synthesize its own hemin from supplied delta-aminolevulinic acid)
• organisms capable of synthesizing their own porphyrins have no hemin requirement (ALA positive)

Question 14

when we isolate H. influenzae, what screening test do we always do?

Answer 14

B lactamase production by chromogenic cephalosporin method
- rapidly indicates ampicillin resistance

Question 15

T or F. Bordetella pertussis won’t grow on BAP but will grow on CAP

Answer 15

F!
- charcoal containing media for transportation (Jones-Kendrick, Regan-Lowe, Amies)
- highly susceptible to toxic effects of unsaturated fatty acids, peroxide, and sulfides
- primary isolation media requires charcoal or starch and high concentrations of blood = Bordet-Gengou

Question 16

specimens for whooping cough

Answer 16

tiny calcium alginate swab - nasopharyngeal

Question 17

characteristics of B. pertussis

Answer 17

• strict aerobe
• split-pearl or drops of mercury
• ox pos
• biochemically non-reactive
• agglutination, DFA, PCR for ID

Question 18

This shows bipolar staining in direct smears particularly when stained with Giemsa

Answer 18

Pasteurella multocida

Question 19

T or F. P. multocida grows on BAP

Answer 19

T, BAP CO2 = non-hem trans colonies w a musty odor (due to indole production)
does not grow on MAC; but ferments glucose (weak TSI rxn)

Question 20

Pasteurella biochemical tests rxn

Answer 20

TSI sick yellow
ox and cat +
nitrate and ornithine decarb +
nonmotile
urease neg
susceptible to penicillin
spot indole +

Question 21

what will clue us that we need to work in the BSC

Answer 21

sterile sites direct smear = gnb or gncb and BAPss does not show sats
BSC to rule out risk group III

Question 22

what can if germ tube test is incubated longer than 2.5 hrs

Answer 22

pseudohyphae will start to develop
needs to be straight and no constricture

Question 23

gram neg cb that is high risk of lab-acquired infection

Answer 23

Brucella sp

Question 24

Brucella sp. biochemical tests

Answer 24

grows on BAP and CAP but requires 4-6 wks incubation in CO2
ox, cat +
urease and nitrate +
doesn’t grow on MAC