Actinobacillus

(microbiology) A species of gram-negative, oval, spherical, or rod-shaped bacteria that are of uncertain affiliation; coccal and bacillary cells are often interspersed, giving a “Morse code” form; species are pathogens of animals, occasionally of humans.

A genus of gram-negative, immotile and nonspore-forming, oval to rod-shaped, often pleomorphic bacteria which occur as parasites or pathogens in mammals (including humans), birds, and reptiles. They are facultatively aerobic, capable of fermenting carbohydrates (without production of gas) and of reducing nitrates. The genomic DNA contains between 40 and 47 mol % guanine plus cytosine. The actinobacillus group shares many biological properties with the genus Pasteurella. See also Pasteurella.

Actinobacillus (Pasteurella) ureae and A. hominis occur in the respiratory tract of healthy humans and may be involved in the pathogenesis of sinusitis, bronchopneumonia, pleural empyema, and meningitis. Actinobacillus actinomycetemcomitans occurs in the human oral microflora, and together with anaerobic or capnophilic organisms may cause endocarditis and suppurative lesions in the upper alimentary tract. Actinobacilli are susceptible to most antibiotics of the β-lactam family, aminoglycosides, tetracyclines, chloramphenicol, and many other antibacterial chemotherapeutics. See also Antibiotic; Medical bacteriology.

A genus of nonmobile, gramnegative aerobic and facultatively anaerobic bacteria of the family Brucellaceae that is pathogenic to cattle, sheep, horses, and pigs.

A genus of bacteria which are gram-negative, pleomorphic rods.

• A. actinoides — a secondary agent in seminal vesiculitis in bulls and enzootic pneumonia in calves.
• A. actinomycetemcomitans — associated with epididymitis in rams and periodontal disease and endocarditis in humans.
• A. capsulatus — the cause of arthritis and septicemia in rabbits.
• A. equuli — the cause of septicemia and subsequent focal lesions in young foals and also peritonitis in adult horses. Previously called Shigella equirulis.
• A. lignieresi — the cause of actinobacillosis of cattle and sheep, and occasionally in pigs, dogs and humans.
• A. mallei — see burkholderia mallei.
• A. pleuropneumoniae — causes severe pleuropneumonia and pleuritis in pigs. Previously Haemophilus pleuropneumoniae.
• A. salpingitidis — the proposed name for a bacteria which is isolatable from cases of salpingitis, peritonitis, airsacculitis and pneumonia in birds. Called also Pasteurella salpingitis.
• A. seminis — the cause of epididymitis and periorchitis in rams.
• A. suis — the cause of septicemia and subsequent focal lesions in young pigs.
• A. ureae — may be a cause of abortion in sows.