Haemophilus

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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 ?
Synovial fluid cultures from the initial arthrocentesis were now growing Haemophilus parainfluenzae with colonies observed on solid media within 24 hours of inoculation.
Pujol, "Isolation of Haemophilus influenzae and Haemophilus parainfluenzae in urethral exudates from men with acute urethritis: a descriptive study of 52 cases," Sexually Transmitted Infections, vol.
agalactiae, Group C streptococci, Haemophilus influenzae, Haemophilus parainfluenzae, Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, and Morganella morganii) were collected (one per patient episode) from patients in Latin American medical centers during 2011.
Abscess fluid cultures from drainage revealed Prevotella intermedia, Haemophilus parainfluenzae and Streptococcus spp.
Infectious causes of acute COPD exacerbations Bacteria Viruses Non-typeable Haemophilus influenzae Rhinovirus Moraxella catarrhalis Influenza Streptococcus pneumoniae Parainfluenza Pseudomonas aeruginosa Coronavirus Enterobacteriaceae Adenovirus Haemophilus parainfluenzae Respiratory syncitial virus 'Atypical bacteria' Human metapneumovirus
Haemophilus parainfluenzae is a gram-negative bacterium that is a normal habitant and an opportunistic pathogen of the respiratory tract.
FACTIVE is also approved for the five-day treatment of AECB due to Streptococcus pneumoniae, Haemophilus influenzae, Haemophilus parainfluenzae, or Moraxella catarrhalis.
In 2004, FACTIVE was approved in Canada for the treatment of AECB caused by Streptococcus pneumoniae, Haemophilus influenzae, Haemophilus parainfluenzae, Moraxella catarrhalis and Staphylococcus aureus.
FACTIVE is approved for the five-day treatment of AECB caused by Streptococcus pneumoniae, Haemophilus influenzae, Haemophilus parainfluenzae or Moraxella catarrhalis and for the seven-day treatment of mild to moderate CAP caused by Streptococcus pneumoniae (including multi-drug resistant strains), Haemophilus influenzae, Moraxella catarrhalis, Mycoplasma pneumoniae, Chlamydia pneumoniae or Klebsiella pneumoniae.
FACTIVE tablets are approved in Canada for treating acute bacterial exacerbations of chronic bronchitis caused by Streptococcus pneumonia, Haemophilus influenzae, Haemophilus parainfluenzae, Moraxella catarrhalis and Staphylococcus aureus.
In adult and adolescent patients, Omnicef is also indicated for community acquired pneumonia and acute exacerbations of chronic bronchitis caused by Haemophilus influenzae, including beta-lactamase-producing strains, Haemophilus parainfluenzae, including beta-lactamase-producing strains, Morexella catarrhalis, including beta-lactamase-producing strains, and penicillin-susceptible strains of Streptococcus pneumoniae.

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