Haemophilus

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Author:
ehamm
ID:
117626
Filename:
Haemophilus
Updated:
2011-11-17 22:17:37
Tags:
Haemophilus
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Description:
Haemophilus
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  1. Organism
    • Gram negative bacilli
    • Coccobacilli
    • Special culture: NAD and Hematin
    • Some have capsules, some don't
    • Type B: capsule is polymer of ribose, ribitol and phosphate (PRP), Strongly assoc. w/ virulence
  2. Epidemiology
    • Commensal NP flora in 90%
    • Meningitis most common form, prefers < 2 yrs
    • Epiglottitis/pneumonia in 2-5 yo
    • 1/200 before vaccine
    • Prophylaxis with rifampin for unimmunized kids
  3. Pathogenesis
    • Invade deeper tissues, baceteremia leads to CNS infections
    • Systemic spread indicates encapsulated bacteria
    • Attachment to respiratory cells mediated by pili, invades between cells of RT
    • Antiphagocytic capsule, IgA proteases
    • LPS and OMPs increase virulence
    • Localized diseases: non-encapsulated, middle ear, sinus, bronchus; assoc with compromise of normal clearing mechanism
  4. Immunity
    • Anti-PRP Ab
    • Protected in first months of life from maternal IgG
    • Peak infection time 6-18 months
    • Systemic infections rare in adults
    • Hib PRP is t-cell independent Ag; creates poor immune response in infants
    • Conjugation creates T-Cell dependent response, increasing effectiveness in infants
  5. Manifestations
    • Meningitis: signs/symptoms of URTI=pharyngitis, sinusitis; malaise, lethargy, irritablity; major signs=nuchal rigidity, high fever, headache; moratility in 3-6%, significant neurological damage in 1/3
    • Epiglottitis: inflammed epiglottis, sudden onset with fever, sore throat, hoarseness, muffled cough
    • Cellulitis/arthritis: tender, reddish blue swelling in cheek with fever and mildly toxic state; arthritis in single large join with fever
    • Other: Conjuctivitis, otitis media, conjunctivitis (non-encapsulated)
  6. Diagnosis
    • Clinical
    • gram smear
    • Confirmed by isolation from site of infection
  7. Treatment
    • Ampicillin, amoxicillin
    • 5-50% resistant
  8. Prevention
    • Conjugated vaccine, reducation in 99% of cases
    • Most infections are now caused by non-encapsulated versions
  9. H. Ducreyi
    • Chanchroid
    • Veneral disease, strict human pathogen, assoc with CSW
    • Disease: skin infection; 4-7 days erythematous papules to pustular stage which rupture to form shallow ulcers; ulcers are soft and painful; can develop bubos in untreated cases; increase risk of HIV
    • Pathogenesis: induces inflammatory response; block phagocytosis; multiple virulence factors
    • Diagnosis: hard to diagnose, poor gram stain, difficult to grow

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