Susceptibility of anaerobic bacteria to Sch 34343 and other antibiotics

The in-vitro activity of Sch 34343 was evaluated against 137 strains of anaerobic bacteria by the agar dilution technique. Sch 34343 was compared with imipenem, cefoxitin, latamoxef (moxalactam), clindamycin and metronidazole. Organisms studied included the Bacteroides fragilis group, other Bacteroides spp., Clostridium perfringens, Cl. difficile, other Clostridium spp. and anaerobic cocci. Overall, Sch 34343 and imipenem were significantly more active than the other antibiotics against most organisms tested, especially the Bact. fragilis group, including clindamycin-resistant strains. Apart from Cl. difficile, which required up to 8 mg/l of Sch 34343 and imipenem for inhibition, all the strains were inhibited by 1 mg/l of Sch 34343 and by 2 mg/l of imipenem. Of the remaining agents tested, against the Bact. fragilis group metronidazole (2 mg/l to inhibit 90% of the strains) was the most active, followed by cefoxitin (16 mg/l), latamoxef (32 mg/l) and clindamycin (32 mg/l). On the basis of its activity in vitro, Sch 34343 appears to be one of the most promising new antimicrobial agents for the treatment of infections involving anaerobic bacteria.