HAEMOPHILUS!!! MICROM 442 deck 16 Flashcards
8 pathogenic species
– H. influenzae (1.8MB)
– H. aegyptius
– H. parainfluenzae
– H. haemolyticus
– H. ducreyi (2.8MB)
GM???
negative
shape?
cocobacilli
media?
Chocolate agar
what type of colonies form?
smooth, flat/convex
type of anaerobe?
facultative
do she move around?
no, non-motile
spores?
no
– Protoporphyrin IX (from hemin) = X factor
– Nicotinamide adenine dinucleotide (NAD) = V factor
Fastidious (especially non-H. influenzae)
they do NOT ferment lactate, what do they ferment?
glucose -> H.ducreyi
ALL species are oxidase
positive
reduce what to what?
Reduce nitrate to nitrite
SOME species are catalase
negative (ducreyi & parainfluenzae)
H. influenzae when encapsulated
– Type B → VACCINE PREVENTABLE (Hib)
– Polysaccharide capsule, key virulence factor
– Uncommon colonizer, BSI more likely
h. influenzae when NTHI (non-encapsulated)
– URT / nasopharyngeal colonizer
– Majority of disease now NTHI
– Strain-specific immunity (recurrences)
Hib Vaccine
> Conjugate vaccine
– Type B capsule (PRP)
– Polyribosyl-ribitol-phosphate
Series started at 2 mos
consequences of type B capsule vax?
drops overall incidence but also creates niches for other serotypes, especially NTHI
Anatomical Basis of
H. influenzae
diseases
Focus on URT-contiguous sites
Anatomical Basis of
H. influenzae
diseases
> Blood stream infection (BSI), hematogenous spread
– endocarditis (HACEK orgs)
– Septic arthritis
– BSI more common with Type B vs NTHI
Lower Respiratory Tract Infection
> Pneumonia
– Often insidious
– Two patient pops
Kids 4mos – 4yrs
(Older) adults with bronchociliary dysfunction (COPD, smoking)
Uncommon cause of community acquired PNA (CAP)
NTHI important cause of COPD exacerbations
– ~15% of invasive Hib (pre-vaccine)
Capsule virulence factors
(esp type B)
Adhesins
Protein E, OMP2, Type IV Pilus, other
fimbriae
ceftriaxone, cefotax,
amp-sulbactam
IV abx for more series infx
if R
Amoxicillin or Amox-Clavulanate
