• gram neg
• coccobacillus
• encapsulated strains (a-f)
  • type B is predominant (Hib) with polyribosyl ribitol phosphate (PRP)
• also unencapsulated strains, aka non typable (NTHi)

blood factors:

• factor X (hemin)
• factor V (NAD)

what diseases tend to be caused by unencapsulated H.influenzae?

• infections tend to be more localized respiratory infections with unencapsulated Hi:
  • otitis media
  • sinusitis
  • bronchitis
  • pneumonia
  • COPD

what diseases tend to be caused by encapsulated H.influenzae?

encapsulated Hi causes more diffuse infections:

• meningitis in kids
• septic arthritis in kids
• bacteremia w/ fever and no localization
• cellulitis involving face
• epiglottitis

what is Hi's most important virulence factor and what are some others?

• most important: polysaccharide capsule (PRP is imp component for Hib)
• adherence factors:
  • pilus (hif genes)
  • non pilus adhesins (nontypeable strains)
  • hap adhesin (nontypeable strains)
  • mucus binding proteins
• iron uptake proteins
• lipooligosaccharide (LOS)
• biofilm formation

in a mouse model of the upper respiratory tract, which organism does better and why: Hib vs. Strep pneumoniae?

Hib outcompetes Strep pneumoniae in the UR tract when the two are both present; strep pneumoniae infections are cleared in a complement and neutrophil mediated way that leaves Hib relatively unbothered, likely due to its encapsulation which makes it hearty against these immune attacks!

• amoxicillin
• 3rd gen cephalosporins (severe infections)
• rifampin for chemoprophylaxis
• VACCINES
  • PRP-protein conjugate, which significantly reduced incidence of childhood meningitis

• L.pneumophila
• morphology:
  • gram neg bacillus on med & coccobacillus on tissue

• legionnaire's disease:
  • severe pneumonia
  • fever, dry cough, multiorgan invmnt pssble
  • high mortality rate (15-20%)
  • low attack rate, no p-2-p spread
• pontiac fever:
  • low mortality
  • flu like illness
  • high attack rate