Bacteremia due to anaerobic bacteria in newborns

Awareness of the role of anaerobic bacteria in neonatal bacteremia has increased in recent years. The incidence of recovery of anaerobes in neonatal bacteremia varies, according to different studies, between 1.8% and 12.5%. Of the 178 cases reported in the literature, 73 were due to Bacteroides species (69 were the Bacteroides fragilis group), 57 Clostridium species (mostly Clostridium perfringens), 35 Peptostreptococci, 5 Propionibacterium acnes, 3 Veillonella species, 3 Fusobacterium species, and 2 Eubacterium species. Predisposing factors were perinatal maternal complications (especially premature rupture of membranes and chorioamnionitis), prematurity, and necrotizing enterocolitis. Organisms similar to those recovered in blood were concomitantly isolated in lung aspirates and cerebrospinal and peritoneal fluids. The overall mortality noted is 26% and is highest with B fragilis group (34%). Inappropriate antimicrobial therapy was often a contributory factor for such mortality. Correction of underlying pathology, surgical drainage, and the use of proper antimicrobials are critical to successful resolution of the infection. Penicillin G is the drug of choice for anaerobic infection other than beta-lactamase-producing Bacteroides. Antimicrobials useful for therapy of beta-lactamase-producing Bacteroides include clindamycin, metronidazole, chloramphenicol, imipenem-cilastatin, and the combination of a penicillin plus a beta-lactamase inhibitor.