Bugs - Haemophilus, Legionella, Bordetella Flashcards
clinically relevant haemophilus species
**H. influenzae **(most important)
**H. ducreyi **(chancroid, genital ulcers)
morphology of haemophilus
small, GN, coccobaccilli
required factors for culturing haemophilus?
need X factor(hemin) and V factor(NAD)
requires chocolate agar: heated blood agar which causes the release of these factors
H. influenzae virulence factors
- polysacchardie capsule(if encapsulated obviously)
-
adherence factors
- pili
- HMW adhesins(unencapsulateD)
- lipooligosaccharide(LOS)- can be modified by sialic acid terminal addition
- biofilm formation(LOS sialylation)
treatment for H. influenzae
unencapsulated/non-invasive - amoxicillin; amoxicillin-clavulanate for resistant strands
Hib(meningitis) - cefotaxamine(3rd gen cephalo)
most clinically relavent moraxella species
m. catarrhalis
types of moraxella infections and treatment
otitis media, sinusitis, conjuctivitis(rarely systemic) treat with amoxicilin/clavulanate use cephalosporins for more serious
h. influenzae diseases(encapsulated and unencapsulated)
Hib - meningitis, conjuctivitis, cellulitis, epiglottitis, bacteremia, arthritis (ABCCME)
unencapsulated - otitis media, sinusitis, bronchitis, pneumonia (BOPS)
treatment for h. influenzae
amoxicillin for non-invasive(unencapsulated); amoxicillin-clavulanate for resistant strands
3rd gen cephalosporin(cefotaxamine) for invasive Hib(meningitis)
describe the h. influenzae vaccine
PRP(polyribosyl ribitol phosphate) attached to protein conjugate
treatment for moraxella infections
treat m. catarrhalis with amoxicillin/clavulanate, cephalosporins
just like haemophilus
clinically relevant legionella spp.
L. pneumophilia
how are legionella infections spread?
aerosolized water sources:
- showers
- whirlpools
- humidifiers
- tap water/faucets
- cooling towers
who is at higher risk for legionella infections?
elderly/immunocompromised
smoking, chronic lung disease, TLR5(flagellum) polymorphism
pathogenesis for L. pneumophilia
- attach/entry into alveolar macrophages(bind C’, type IV pili)
- inhibit fusion of phagolysosome
- begins replicating in vacuole
- secretes virulence factors via Dot/Icm type IV secretion system
- keeps growing till cell lyses then moves to next cell
diseases caused by legionella
-
Legionnaires Disease - severe pneumonia
- fever, nonproductive cough, chills, HA
- cerebellar involvement often
- 15-20% moretality
- need antibiotics
-
Pontiac Fever - flu like symptoms(mild)
- high attack rate, but <1% mortality
- no person-person spread
- no therapy needed
diagnostics for legionella
hard to gram stain
- use Giminez(smears) or Dieterle(tissue) stains
- urine antigen test(detects LPS serogroup 1)
- direct fluorescent a-body test from sputum
treatment for legionella
fluoroquinolones(levofloxacin) for CA-pneumonia
- change to azithromycin if legionella is diagnosed
coxiella
relavent species?
epidemiology?
C. burnetii is most relavent species
found in animal reservoirs; commonly seen in farmers, ranchers, vets
coxiella
diseases?
treatment?
Q fever(self-limiting flu-like illness) –> chronic form includes endocarditis
Treat with doxycycline
corynebacterium
relavent species?
morphology?
disease, toxins?
treatment?
corynebacterium diphtheriae
aerobic GP rod
Diptheria: acute resp. infection w/pseudomembrane formation in throat
- resp. failure, myocarditis, neuritis, death
- uncommon in US
- mediated by diptheria toxin - inhibits protein synthesis
Treatment: antitoxin serum plus erythromycin or penicillin
relavent bordetella species
**b. pertussis **(whoopin cough)
**b. parapertussis **(milder disease)
GN coccobacilli
no capsule
small
causes whooping cough
bordatella
b. pertussis specifically
bordatella toxins/virulence factors
- pertussis toxin (PTX):
- ADP-ribosyl transferase(Gi protein target)
- causes lymphocytosis(systemic disease); bad prognosis
- immunosuppressive when infecting, then causes inflamm later…bad
_ other toxins:_
a) adenylate cyclase toxin – targets and inactivates neutrophils
b) tracheal cytotoxin and **lipopolysaccharide - **combine to destroy cilia on epthelial cells
bordatella treatment
- azithromycin or clarithromycin to prevent spread(doesnt stop symptoms)
- supportive therapy - hydration, nutrition, oxygen
epidemiology of bordatella
- HIGHLY contagious; spread via aerosols
- majority of cases in young children, most deaths <1 y/os
- adults have less severe symptoms but are likely reservoirs
diagnosis of bordatella
culture on bordet-gengou or regan-lowe mediums
PCR, serology
stages of bordatella disease
- *1. catarrhal stage** - cold-like symptoms, highly infectious, 2 weeks
- *2. paroxysmal stage** - severe cough paroxysms, apnea, may cause hypoxia, striking leukocytosis
**3. ** convalescent stage - cough may persist for several months, bacteria absent
**4. ** critical pertussis in infants
- **lymphocytosis**, apnea, can progress to respiratory failure and death
morphology of coxiella
GN, intracellular bacillus
related to legionella
