Haemophilus

(redirected from Haemophilus influenzae)
Also found in: Dictionary, Medical, Acronyms, Wikipedia.

Haemophilus

A genus of gram-negative, pleomorphic bacteria that are facultative anaerobes and are nonmotile and non-spore-forming.

Haemophilus influenzae was the first of the species to be isolated and is considered the type species. It was originally recovered during the influenza pandemic of 1889 and for a time was believed to be the causative agent of influenza; thus it was called the influenza bacillus. However, when this fallacy became apparent, the organism was renamed, still reflecting the historical association with influenza.

Haemophilus species are distinguished by a number of criteria. Strains of H. influenzae can be separated into encapsulated and nonencapsulated forms. Encapsulated strains express one of six biochemically and antigenically distinct capsular polysaccharides that are designated serotypes a through f. Nonencapsulated strains are referred to as nontypable. See Influenza, Meningitis

Haemophilus influenzae is a human-specific pathogen that inhabits the upper respiratory tract and is acquired by exposure to airborne droplets or contact with respiratory secretions. Nontypable strains can be isolated from the nasopharynx of up to 80% of normal children and adults at any given time, usually in association with asymptomatic colonization. Overall, these organisms are the leading cause of exacerbations of chronic bronchitis, and the second most common etiology of acute otitis media and sinusitis. On occasion, nontypable H. influenzae causes invasive disease such as meningitis, septicemia, endocarditis, epiglottitis, or septic arthritis. Invasive disease occurs most often in neonates and in patients with underlying immunodeficiency, especially when abnormalities in humoral immunity are present.

Encapsulated strains of H. influenzae are present in the nasopharynx of only 2–5% of children and an even smaller percentage of adults. Historically, H. influenzae type b strains were the primary cause of childhood bacterial meningitis and a majority of other bacteremic diseases in children. However, in recent years the incidence of disease due to H. influenzae type b has plummeted in the United States and other developed countries, reflecting the routine use of H. influenzae conjugate vaccines. These vaccines provide effective protection against disease due to H. influenzae type b but fail to protect against non-type b strains.

Haemophilus aphrophilus, H. haemolyticus, H. parahaemolyticus, H. parainfluenzae, and H. segnis are members of the normal flora in the human oral cavity and oropharynx and have low pathogenic potential. Among these species, H. parainfluenzae is the most common pathogen and has been reported in association with a variety of diseases.

Strains of H. influenzae are increasingly resistant to a wide variety of antibiotics. Accordingly, an extended-spectrum cephalosporin is generally recommended for empiric treatment of serious disease. See Antibiotic, Drug resistance, Medical bacteriology

Haemophilus

[hē′mä·fə·ləs]
(microbiology)
A genus of gram-negative coccobacilli or rod-shaped bacteria of uncertain affiliation; cells may form threads and filaments and are aerobic or facultatively anaerobic; strictly blood parasites.
References in periodicals archive ?
Invasive disease caused by Haemophilus influenzae in Sweden 1997-2009; evidence of increasing incidence and clinical burden of non-type b strains.
Haemophilus influenzae Type B Infections - Products under Development by Companies 16
Haazen et al., "Phase I, randomized, observer-blind, placebo-controlled studiesto evaluate the safety, reactogenicity and immunogenicity of an investigational non-typeable Haemophilus influenzae (NTHi) protein vaccine in adults," Vaccine, vol.
The protective level of serum antibodies to the capsular polysaccharide of Haemophilus influenzae type b.
CLC Main Workbench 5 software revealed that sample numbers 1, 2 and 3 were similar to strains of nontypeable Haemophilus influenzae with GenBank accession numbers (Gan), AY497551, HIU08876 and AY497554, respectively (Figure 3).
Appelbaum, "Antimicrobial resistance in Haemophilus influenzae," Clinical Microbiology Reviews, vol.
Its recent efforts in the vaccine business include clinical testing of the Haemophilus Influenzae type b (Hib) vaccine and the development of a combination vaccine containing a Sabin-inactivated poliovirus (s-IPV) vaccine, which Takeda believes is likely to play an important role in polio eradication.
Vishniakova and Beliaeva studied respiratory specimens and found that Streptococcus pneumoniae survived four to seven days in specimens stored in a "common" refrigerator (specimen-type dependent), and Haemophilus influenzae could be detected for up to 48 hours.
Researcher Chien-Chang Lee and his colleagues at the Harvard School of Public Health also found a possible association of second-hand smoke exposure with invasive pneumococcal disease and Haemophilus influenzae type b.
Effectiveness of Haemophilus influenzae type B conjugate vaccine on prevention of pneumonia and meningitis in Bangladeshi children: a case-control study.

Full browser ?