Haemophilus and Bordetella Flashcards
H. influenzae bacteriology
- stain and shape
- mobility
- culture
- gram (-) pleomorphic rod (coccobacillus)
- nonmotile, non spore forming
- will only grow w/ factors X (heme) and V (NAD)
Which version of H flu is most pathogenic? (Why?) Which serotype causes the most severe disease?
capsulated version (immune evasion); serotype B
What is the target for the H flu vaccine
Hib polyribosyl ribitol phosphate capsule
What is the presentation of infection w/ unencapsulated strains of H flu in immunocompetence
local mucosal infection, asymptomatic carriage
Hib virulence factors: colonization
IgA protease - clears IgA from resp mucosa
What determines the severity of disease in Hib infection
magnitude and duration of bacteremia
What is the mortality rate for unvaccinated/untreated Hib meningitis? Outlook for survivors?
90%; of survivors 50% will have neurologic sequelae
What age group is most at risk for Hib infection
children from 6mo-6yrs (esp 6mo-1yr)
When does NTHi infection become serious
pneumonia in CF, neonatal sepsis, maternal sepsis after vaginal delivery
Hib meningitis presentation
- in infants
- Dx
rapid-onset fever, altered mental status, headache, stiff neck
- lethal within hours
- lumbar puncture and gram stain
Hib cellulitis presentation
raised, indurated, tender area usually on head or neck, may effect eyes
Hib otitis media, sinusitis presentation
pain/swelling, bulging tympanic membrane
What is the number one red flag that you are looking for clinically w/ Hib infection
epiglottitis -> can cause respiratory failure, inability to swallow (drooling)
NTHi in neonates
associated w/ prematurity, LBW, presentation w/i 24hrs of birth w/ bacteremia, sepsis, meningitis, pneumonia, conjunctivitis, cellulitis
NTHi in postpartum
sepsis w/ endometritis, tubo-ovarian abscess, chronic salpingitis
H flu Dx: lab
gram stain, culture on chocolate agar w/ and w/o factors X and V, sensitivity testing
H flu meningitis Dx lab
CSF w/ elevated neutrophils, decreased glucose, increased protein, and positive capsular antigen
Treat H flu meningitis
ceftriaxone first, sensitivity second
children under 2: add dexamethasone
Treat H flu respiratory
amox + clavulanate OR trimethoprim + sulfamethoxazole
Treat H flu cellulitis, pericarditis, septic arthritis
drainage w. trimeth+sulfa, cefuroxime, axetil, cefixime, clarithromycin, azithro, fluoroquinolones
B pertussis bacteriology
- stain and shape
- transmission
- disease and target population
- gram (-) rod (coccobacillus)
- respiratory droplets
- whooping cough in infants under 2yrs
Most important virulence factor for B pertussis (function?)
filamentous hemagglutinin pilus; attaches bacteria to cilia of epithelial cells lining the resp tract and blocks cilia movement (clogging > forceful coughing > more spread)
Pertussis toxin
A-B subunit ADP-ribosylator: kills ciliated cells and inhibits chemokine signal transduction (lymphocytosis)
B. pertussis Tracheal cytotoxin
also kills ciliated cells
Three stages of Pertussis: Catarrhal
1st stage: (2wk) nonspecific, congestion. sneezing, rhinorrea, maximally contagious
Three stages of Pertussis: Paroxysmal
2nd stage: (2wk) intense coughing, hacking cough w/ copious mucus production, inspiratory ‘whoop’ as air rushes past narrowed glottis. Infants turn blue, children turn red and vomit
Three stages of pertussis: convalescence
third stage: (2mo) fatigue, chronic cough
Blood work in pertussis infection
pronounced leukocytosis with up to 70% lymphocytes
How do you culture pertussis
Bordet-gengou agar
Treating pertussis
macrolides, supportive care
