THE IMPORTANCE OF BLACK-PIGMENTED GRAM-NEGATIVE ANAEROBES IN HUMAN INFECTIONS

Black-pigmented Gram-negative anaerobic rods are found on mucosal surf aces as indigenous flora. With mucosal damage due to disease, trauma o r surgery, these organisms may invade tissues and set up infection. Ot her important factors determining whether or not infection results inc lude 'inoculum' size, synergy with other organisms and production of v irulence factors that include capsules, lipopolysaccharide, attachment factors, proteases, collagenase, neuraminidase, and phospholipase A; also, they may have fibrinolytic and anti-phagocytic activity and may degrade complement and IgG and IgM. Pigmented anaerobes are found in a ll types of infections including such serious infections as bacteraemi a, endocarditis, intracranial abscess, necrotizing pneumonia and necro tizing fasciitis, generally as part of a mixed infecting flora, and th ey play a key role in experimental mixed infections. They dominate or are prominent in infections involving organisms originating in the oro pharynx, such as central nervous system, head and neck, dental and ple uropulmonary infections. Therapy of infections involving pigmented ana erobes includes surgery plus antimicrobial agents; a significant perce ntage of strains produce beta-lactamase. Much remains to be done to de termine the relative importance of the various taxa of black-pigmented Gram-negative anaerobes and of the different virulence factors produc ed by them.