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Haemophilus species

Haemophilus species is a topic covered in the Johns Hopkins ABX Guide.

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MICROBIOLOGY

  • Small aerobic Gram-negative coccobacillus found mainly in the respiratory tract.
    • Fastidious organism, factors X (hemin, haemophilius from Latin "blood loving") and V (nicotinamide-adenine-dinucleotide) required for growth on chocolate agar, the preferred media
  • Haemophilus influenzae: two categories causing human colonization or infection
    • Typeable strains: six types generally recognized (Types a-f).
      • Encapsulated, type B strain (Hib, with capsular antiphagocytosis and anticomplement virulence factors) historically accounts for most invasive infections and bacteremic pneumonia. Now rarely encountered due to childhood Hib vaccine success.
      • H. influenzae serotype a (Hia) increasingly noted as a cause of severe, invasive infection. Emergence due to intrinsic capsular virulence factors of Hia was well as pressure from the success of Hib immunization.
        • Predominantly noted in U.S. and Canada. Incidence in Europe, low.
        • In one series, accounted for ~30% of invasive H. influenzae infection in Manitoba.
      • Type f strain also increasingly recognized as a cause of severe infection, though less common than Hia.
    • Non-typeable strains: less invasive and cause more otitis media, epiglottitis, acute exacerbations of chronic bronchitis (AECB), sinusitis and nonbacteremic pneumonia.
      • Increasingly recognized as a cause of URTIs, pneumonia and occasional bacteremia in all age groups.
      • High colonization rates in children, up to 70%.
      • Recent data suggest that non-typeable strains (along with Hia) are accounting for greater percentages of invasive Haemophilus disease[4].
  • Other species: all are part of normal flora of human oral and pharyngeal cavities but may also be causes of bacterial respiratory tract infections and endocarditis, similar to H. influenzae.
  • H. ducreyi, agent of chancroid, see the separate module.

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Last updated: April 5, 2019

Citation

Auwaerter, Paul. "Haemophilus Species." Johns Hopkins ABX Guide, The Johns Hopkins University, 2019. Johns Hopkins Guide, www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540253/all/Haemophilus_species.
Auwaerter P. Haemophilus species. Johns Hopkins ABX Guide. The Johns Hopkins University; 2019. https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540253/all/Haemophilus_species. Accessed May 26, 2019.
Auwaerter, P. (2019). Haemophilus species. In Johns Hopkins ABX Guide. Available from https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540253/all/Haemophilus_species
Auwaerter P. Haemophilus Species [Internet]. In: Johns Hopkins ABX Guide. The Johns Hopkins University; 2019. [cited 2019 May 26]. Available from: https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540253/all/Haemophilus_species.
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TY - ELEC T1 - Haemophilus species ID - 540253 A1 - Auwaerter,Paul,M.D. Y1 - 2019/04/05/ BT - Johns Hopkins ABX Guide UR - https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540253/all/Haemophilus_species PB - The Johns Hopkins University DB - Johns Hopkins Guide DP - Unbound Medicine ER -