LAB - Haemophilus, Bordetella, Pasteurella, Brucella

Question 1

H. influenzae infections

Answer 1

• normal flora of the URT

- meningitis, epiglottitis, pneumonia, resp. tract infections, celulitis, conjunctivitis

Question 2

T or F. There are six serotypes of H. influenzae

Answer 2

T

Question 3

HiB

Answer 3

used to be a leading cause of meningitis and septicemia in babies, but the incidence as dramatically decreased with the introduction of HiB vaccines

Question 4

H. parainfluenzae

Answer 4

• low incidence of pathogenicity
• endocarditis
• normal bacterial flora in resp tract

Question 5

H. ducreyi

Answer 5

• a sexually transmitted disease known as chancroid

- more prevalent in tropical areas

Question 6

H. haemolyticus and parahaemolyticus

Answer 6

nonpathogenic usually

Question 7

Haemophilus

Answer 7

• small, pleomorphic, gram neg bacilli
• short cb but occasionally also long filamentous thin bacilli
• facultative capnophilic organisms
• “mousy” odor

Question 8

appropriate Haemophilus specimens

Answer 8

blood
sputum
CSF
conjunctival and genital ulcer swabs

Question 9

X factor

Answer 9

hemin

- an iron porphyrin

Question 10

V factor

Answer 10

nicotinamide adenine dinucleotide or NAD

Question 11

why does hseep blood not support Haemphilus sp. growth?

Answer 11

• sheep blood contain NADase = destroys ND
• Haemophilus love factors supplied by red cells
• CAP will support growth of these colonies as heating RBCs destroys NADase ad releases hemin

Question 12

S. colonies with BAP for Haemophilus

Answer 12

• staph streak

- S. aureus will lyse RBCs and produce NAD = Haemophilus will satellite around the Staph colonies

Question 13

ALA test

Answer 13

accurate and rapid means of determining X factor requirement

tests ability of organism to synthesize its own hemin from supplied delta-aminolaevulinic acid (ALA)

organisms capable of synthesizing their own porphyrins have no hemin requirement = ALA positive

Question 14

these can be used for rapid detection of HiB antigen in CSF and serum

Answer 14

latex agglutination and co-agglutination kits

Question 15

red fluorescence following Wood’s light in ALA test

Answer 15

porphyrin positive = no X factor requirement

= parainfluenzae

Question 16

H. parainfluenzae can grow on the plate even with this disc only

Answer 16

V factor

- requires factor V only as it synthesizes its own X

Question 17

Where do you incubate a staph streak?

Answer 17

CO2

Question 18

T or F. About 30-35% of H. influenzae isolates are resistant to ampicillin

Answer 18

T. by virtue of plasmid-mediated constitutive beta-lactamase production which hydrolyzes the B lactam ring of penicillins

Question 19

primary cultures of H. influenzae from blood and CSF should always be screened for B-lactamase production

Answer 19

by the chromogenic cephalosporin method
- a positive test for beta-lactamase provides rapid evidence of ampicillin resistance before conventional susceptibility test results are made available

Question 20

three clinically significant species in Bordetella

Answer 20

• pertussis
• parapertusis
• bronchiseptica

Question 21

appropriate specimens for the cultivation of Bordetella

Answer 21

• nasopharyngeal swabs collected using a tiny calcium alginate swab
• fragile specimen that should be transported immediately to lab in a special charcoal containing media

Question 22

charcoal containing media for Bordetella

Answer 22

• Regan-Lowe
• Jones-Kendrick
• Amies

Question 23

T or F. B. pertussis can grow on BAP/CAP

Answer 23

F! extremely fastidious

- highly susceptible to toxic effects of unsaturated fatty acids, peroxides, sulfides

Question 24

primary isolation media of Bordetella pertussis requires…

Answer 24

• charcoal or starch

- high concentrations of blood (10-20%)

Question 25

classic medium for primary isolation of B. pertussis

Answer 25

Bordet-Gengou (potato starch-glycerol-blood)

• Regan-Lowe medium, Jones-Kendrick, BCYE = secondary culture

Question 26

B. pertussis

Answer 26

• strict aerobe
• “split-pearl” colonial morph or “drops of mercury”
• oxidase positive
• biochemically nonreactive otherwise

Question 27

faintly staining gram neg cb

Answer 27

Bordetella

Question 28

Pasteurella multocida infections

Answer 28

• pathogen of several animal species

- human infection: wound, cellulitis following cat bites and scratches

Question 29

Pasteurella multocida

Answer 29

• gram - cb
• bipolar staining on direct smears when Giemsa stained
• small non-hemolytic transparent colonies with musty odor on BAP (indole)
• colony of freshly isolated virulent strains = smooth, brownish halo
• no growth on MAC
• weak A/A TSI
• oxidase, catalase, nitrate, ornithine decarb positive
• nonmotile, urease neg, susceptible to penicillin

Question 30

high risk of lab-acquired infection; Biosafety level 3

Answer 30

Brucella

Question 31

four Brucella species that originate from animal reservoirs are pathogenic to humans:

Answer 31

• B. melitensis (goats)
• B. abortus (cattle)
• B. canis (dogs)
• B. suis (swine)

Question 32

The majority of lab confirmed cases of brucellosis in humans are based on…

Answer 32

detection of serum antibodies, rather than isolation of organism
- agglutination titre 1:160

Question 33

Brucella colonies

Answer 33

• small, trns colonies requiring 4-6 wks incubation (CO2)
• faintly staining, minute gram - CB
• oxodase, catalase, urease, nitrate pos
• don’t grow on MAC