- predisposing factors for infection
- H. influenza is one of the "SHiN" encapsulated bacteria that poses particular risk to asplenic patients (see Encapsulated Bacteria )
- spreads nasopharynx -> lymphatics -> meninges in case of meningitis
- molecular biology
- capsular type B causes most severe disease
- type B contains ribose in place of hexose
- type B capsule is polyribosyl-ribitol-phosphate
- non-encapsulated strains exist ("nontypable")
- cause otitis media, sinusitis, and bronchitis
- vaccine does not confer immunity to nontypable strains
- produces IgA protease
- Haemophilus causes "EMOP"
- "cherry red" in children
- formerly the most common cause
- in unvaccinated children 3 months to 2 years
- formerly the most common cause in 1-5 year old children (until 1990)
- otitis media
- pneumonia (adults most commonly)
- Does not cause the flu!
- Coccobacillary rods
- Culture on chocolate agar
- requires factors V (NAD+) and X (hematin) for growth
- Satellite phenomenon
- grows near S. aureus on blood agar
- S. aureus supplies factor V
- S. aureus lyses RBCs, releasing factor X
- ceftriaxone for meningitis
- rifampin prophylaxis for close contacts
- contains type B capsular polysaccharide (polyribosyl-ribitol-phosphate - PRP) conjugated to protein (often diphtheria toxoid)
- conjugation improves immune system recognition of polysaccharide and promotes class switching
- confers immunity only to type B
- given between 2 and 18 months of age
- T-cell dependent
AVERAGE 5.0 of 2 RATINGS
Qbank (0 Questions)
Level of Evidence 5 and Other Journal Articles (includes Case Reports, Expert Opinions,
Personal Observations, and Biomechanic Studies)
Sur DK, Bukont EL. Evaluating fever of unidentifiable source in young children. Am Fam Physician. 2007 Jun 15;75(12):1805-11. PubMed PMID: 17619522
PMID:17619522 (Link to Abstract)
Morton DJ, VanWagoner TM, Seale TW, Whitby PW, Stull TL. Catalase as a source of both X- and V-factor for Haemophilus influenzae. FEMS Microbiol Lett. 2008 Feb;279(2):157-61. Epub 2007 Dec 18. PubMed PMID: 18093136.
PMID:18093136 (Link to Abstract)
- First Aid for the USMLE STEP 1. Le, Tao. New York: McGraw-Hill Medical, 2013.
- Rapid Review Pathology Revised Reprint. Goljan, Edward. New York: Mosby, 2011.
- Clinical Microbiology Made Ridiculously Simple 5th Ed. Gladwin, Mark. Miami: MedMaster Inc, 2011.
- medEssentials for the USMLE Step 1. Manley, Michael. New York: Kaplan Publishing, 2012.
- Katzung & Trevnor's Pharmacology Examination and Board Review. Trevor, Anthony. New York: Lange Medical Books, 2012.