LAB - Haemophilus, Bordetella, Pasteurella, Brucella Flashcards
H. influenzae infections
- normal flora of the URT
- meningitis, epiglottitis, pneumonia, resp. tract infections, celulitis, conjunctivitis
T or F. There are six serotypes of H. influenzae
T
HiB
used to be a leading cause of meningitis and septicemia in babies, but the incidence as dramatically decreased with the introduction of HiB vaccines
H. parainfluenzae
- low incidence of pathogenicity
- endocarditis
- normal bacterial flora in resp tract
H. ducreyi
- a sexually transmitted disease known as chancroid
- more prevalent in tropical areas
H. haemolyticus and parahaemolyticus
nonpathogenic usually
Haemophilus
- small, pleomorphic, gram neg bacilli
- short cb but occasionally also long filamentous thin bacilli
- facultative capnophilic organisms
- “mousy” odor
appropriate Haemophilus specimens
blood
sputum
CSF
conjunctival and genital ulcer swabs
X factor
hemin
- an iron porphyrin
V factor
nicotinamide adenine dinucleotide or NAD
why does hseep blood not support Haemphilus sp. growth?
- 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
S. colonies with BAP for Haemophilus
- staph streak
- S. aureus will lyse RBCs and produce NAD = Haemophilus will satellite around the Staph colonies
ALA test
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
these can be used for rapid detection of HiB antigen in CSF and serum
latex agglutination and co-agglutination kits
red fluorescence following Wood’s light in ALA test
porphyrin positive = no X factor requirement
= parainfluenzae
H. parainfluenzae can grow on the plate even with this disc only
V factor
- requires factor V only as it synthesizes its own X
Where do you incubate a staph streak?
CO2
T or F. About 30-35% of H. influenzae isolates are resistant to ampicillin
T. by virtue of plasmid-mediated constitutive beta-lactamase production which hydrolyzes the B lactam ring of penicillins
primary cultures of H. influenzae from blood and CSF should always be screened for B-lactamase production
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
three clinically significant species in Bordetella
- pertussis
- parapertusis
- bronchiseptica
appropriate specimens for the cultivation of Bordetella
- nasopharyngeal swabs collected using a tiny calcium alginate swab
- fragile specimen that should be transported immediately to lab in a special charcoal containing media
charcoal containing media for Bordetella
- Regan-Lowe
- Jones-Kendrick
- Amies
T or F. B. pertussis can grow on BAP/CAP
F! extremely fastidious
- highly susceptible to toxic effects of unsaturated fatty acids, peroxides, sulfides
primary isolation media of Bordetella pertussis requires…
- charcoal or starch
- high concentrations of blood (10-20%)
classic medium for primary isolation of B. pertussis
Bordet-Gengou (potato starch-glycerol-blood)
- Regan-Lowe medium, Jones-Kendrick, BCYE = secondary culture
B. pertussis
- strict aerobe
- “split-pearl” colonial morph or “drops of mercury”
- oxidase positive
- biochemically nonreactive otherwise
faintly staining gram neg cb
Bordetella
Pasteurella multocida infections
- pathogen of several animal species
- human infection: wound, cellulitis following cat bites and scratches
Pasteurella multocida
- 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
high risk of lab-acquired infection; Biosafety level 3
Brucella
four Brucella species that originate from animal reservoirs are pathogenic to humans:
- B. melitensis (goats)
- B. abortus (cattle)
- B. canis (dogs)
- B. suis (swine)
The majority of lab confirmed cases of brucellosis in humans are based on…
detection of serum antibodies, rather than isolation of organism
- agglutination titre 1:160
Brucella colonies
- small, trns colonies requiring 4-6 wks incubation (CO2)
- faintly staining, minute gram - CB
- oxodase, catalase, urease, nitrate pos
- don’t grow on MAC
