Infections caused by anaerobic bacteria are common, and may be serious and life-threatening. Anaerobes predominant in the bacterial flora of normal human skin and mucous membranes, and are a common cause of bacterial infections of endogenous origin. Infections due to anaerobes can evolve all body systems and sites. The predominate ones include: abdominal, pelvic, respiratory, and skin and soft tissues infections. Because of their fastidious nature, they are difficult to isolate and are often overlooked. Failure to direct therapy against these organisms often leads to clinical failures. Their isolation requires appropriate methods of collection, transportation and cultivation of specimens. Treatment of anaerobic bacterial infection is complicated by the slow growth of these organisms, which makes diagnosis in the laboratory only possible after several days, by their often polymicrobial nature and by the growing resistance of anaerobic bacteria to antimicrobial agents.

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Wednesday, April 13, 2011

Propionibacterium species as pathogens

Propionibacterium species are part of the normal bacterial flora that colonize the skin, conjunctiva, oropharynx, and gastrointestinal tract. These non-spore-forming, anaerobic, gram-positive bacilli are frequent contaminants of specimens of blood and other sterile body fluids and have been generally considered to play little or no pathogenic role in humans.
Propionibacterium acnes and other Propionibacterium species have, however, been recovered with or without other aerobic or anaerobic organisms as etiologic agents of multiple infection sites. These include conjunctivitisintracranial abscesses, mycotic aneurysm, peritonitis, and dental, parotid, pulmonary, and other serious infections. They have often been recovered as a sole isolate in specimens obtained from patients with infections associated with a foreign body (such as joint infection, an artificial valve), endocarditis, and central nervous system shunt and post surgical intracranial infections.  Some P. acnes strains possess synergistic capabilities with facultative and aerobic bacteria. The possible role of P. acnes in the pathogenesis of acne vulgaris was suggested. The data that support this are based on the recovery of this organism in large numbers from sebaceous follicles, especially in patients with acne, on its ability to elaborate enzymes such as lipase, protease, and hyaluronidase, and on its ability to activate the complement system and enhance chemotactic activity of neutrophils.

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