A genus of aerobic to facultatively anaerobic, nonmotile bacteria (family Brucellaceae) containing minute, Gram-negative, rod-shaped cells that sometimes form threads and are pleomorphic. These organisms are strictly parasitic, growing best, or only, on media containing blood. They may or may not be pathogenic. They occur in various lesions and secretions, as well as in normal respiratory tracts, of vertebrates. The type species is H. influenzae. [G. haima, blood, + philos, fond]
- H. actinomycetemcomitans SYN: Actinobacillus actinomycetemcomitans.
- H. aegyptius a bacterial species that causes acute or subacute infectious conjunctivitis in warm climates. SYN: Koch-Weeks bacillus.
- H. aphrophilus a bacterial species found in the blood and, rarely, on the heart valve as a cause of endocarditis.
- H. ducreyi a bacterial species that causes the sexually transmitted soft chancre (chancroid). SYN: Ducrey bacillus.
- H. haemolyticus a bacterial species that is usually nonpathogenic but which, on rare occasions, causes subacute endocarditis.
- H. influenzae a bacterial species found in the respiratory tract that causes acute respiratory infections, including pneumonia, acute conjunctivitis, otitis, and purulent meningitis in children (rarely in adults in whom it contributes to sinusitis and chronic bronchitis). Originally considered to be the cause of influenza, it is the type species of the genus H.. SYN: influenza bacillus, Weeks bacillus.
- H. influenzae Type b the most virulent serotype (there are six, a–f, based on antigenic typing of the polysaccharide capsule); species responsible for meningitis and respiratory infections in young children.
- H. parahaemolyticus a bacterial species found in the upper respiratory tract and associated frequently with pharyngitis; occasionally causes subacute endocarditis.
- H. parainfluenzae a bacterial species that is usually nonpathogenic but which occasionally causes subacute endocarditis.
- H. paratropicalis a relatively nonpathogenic bacterial species that has been associated with human infection, including cases of endocarditis.
- H. segnis a usually saprophytic bacterial species that occasionally causes endocarditis, meningitis, and other infections in humans.
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hae·moph·i·lus hē-'mäf-ə-ləs n
1) cap a genus of nonmotile gram-negative facultatively anaerobic rod bacteria of the family Pasteurellaceae that include several important pathogens (as H. influenzae associated with human respiratory infections, conjunctivitis, and meningitis and H. ducreyi of chancroid)
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n.
a genus of Gram-negative aerobic nonmotile parasitic rodlike bacteria frequently found in the respiratory tract. They can grow only in the presence of certain factors in the blood and/or certain coenzymes: they are cultured on fresh blood agar. Most species are pathogenic: H. aegyptius causes conjunctivitis, and H. ducreyi soft sore (chancroid). H. influenzae is associated with acute and chronic respiratory infections (see also epiglottitis) and is a common secondary cause of influenza infections; H. influenzae type B is an important cause of bacterial meningitis in young children (see Hib vaccine).
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Hae·moph·i·lus (he-mofґĭ-ləs) [hemo- + Gr. philein to love] a genus of gram-negative, aerobic or facultatively anaerobic, rod-shaped or coccobacillary bacteria of the family Pasteurellaceae, consisting of cells that sometimes form threads and filaments. The organisms require one or both growth factors (X factor, which can be replaced by hematin, or V factor, which can be replaced by nicotinamide adenine dinucleoside) present in blood. They are normal inhabitants of the upper respiratory tract but may become primary or secondary pathogens.Medical dictionary. 2011.