Comparative efficacy of four antibiotics in anaerobic pulmonary infection. An experimental model in rabbits.

The efficacy of cefoxitin, mezlocillin, latamoxef and metronidazole in anaerobic lung infection was studied using a rabbit model. A mixture of Bacteroides fragilis, Peptococcus morbillorum, Eubacterium lentum and Fusobacterium nucleatum was inoculated transtracheally to produce infection within the lung. Mezlocillin was most effective, achieving bacteriologic cure in 5 out of 8 animals. With cefoxitin therapy, 4 out of 8 became bacteriologically sterile. Severe diarrhea with elevated titers of Clostridium difficile toxin was noted in most cefoxitin-treated animals. Latamoxef- and metronidazole-treated animals had apparently healed lesions, but cultures were positive in 6 and 7 out of 8 in each group, respectively. The commonest pathogen isolated in the last two groups was P. morbillorum. The therapeutic superiority of mezlocillin over metronidazole and latamoxef was statistically significant (p less than or equal to 0.05).