Comparative In Vitro Activity of New Beta-Lactam Antibiotics Against Anaerobic Bacteria

Abstract

Several new beta-lactam antimicrobial agents have been introduced in the last few years. In this investigation, the in vitro activities of several recently introduced cephalosporins (cefoperazone, cefotaxime, ceftazidime, and ceftizoxime), moxalactam, and N-formimidoyl thienamycin were compared with those of cefoxitin, clindamycin, and metronidazole against 203 strains of anaerobic bacteria. At achievable serum levels, all of the antimicrobial agents were active against essentially 100% of the strains of anaerobic gram-positive cocci, Clostridium perfringens, Leptotrichia buccalis, and species of Selenomonas, Veillonella, and Eubacterium. Clindamycin, metronidazole, and N-formimidoyl thienamycin were the most active agents against the Bacteroides fragilis group, inhibiting all strains at concentrations which can be achieved in serum. Of the remaining agents tested against the B. fragilis group, cefoxitin (which required 64 ,tg/ml to inhibit 90% of the strains) was the most active, followed by cefoperazone (128 ,ug/ml), cefotaxime (128 ,tg/ml), moxalactam (128 ,ug/ml), ceftizoxime (256 ,ug/mi), and ceftazidime (>256 pg/ml). Important differences in cephalosporin susceptibility among species of the B. fragilis group were observed. Metronidazole and N-formimidoyl thienamycin were the most active drugs against species of clostridia other than C. perfringens; the other antibiotics displayed poor activity, although this is partly due to inclusion of a relatively large number of strains of Clostridium difficile which were very resistant to several of the cephalosporins. Only metronidazole was active against all species of Fusobacterium. Clindamycin and N-formimidoyl thienamycin displayed excellent activity against gram-positive, non-spore-forming bacilli, requiring c8 ytg/ml to inhibit 100% of the strains. Ceftazidime, cefoperazone, and moxalactam were bactericidal for 25 strains of B. fragilis at concentrations equal or close to those required for inhibition. On the basis of its activity in vitro, N-formimidoyl thienamycin appears to be the most promising of the new beta-lactam antibiotics for the treatment of infections involving anaerobic bacteria.Several new beta-lactam antibiotics have been introduced in the last few years. Several recently introduced cephalosporins, including ceftizoxime, cefoperazone, cefotaxime, and ceftazidime, are distinguished from earlier cephalosporins by increased resistance to beta-lactamase degradation and extended antibacterial spectrum. N-formimidoyl thienamycin, a stable derivative of thienamycin, and moxalactam are beta-lactam antibiotics with potent and broad-spectrum activities.The purpose of the present study was to examine the in vitro activity of these new compounds against various strains of anaerobic bacteria. Using an agar dilution technique, the act Present address:

In vitro activity of Sch 34343 and cefbuperazone against anaerobic bacteria

“…Our data are also in agreement with previous studies examining the in vitro activity of cefoxitin (13,18) fragilis are dominant in anaerobic pleuropulmonary infections (1), the reduced in vitro activity of cefbuperazone against these two genera is of some concern and may limit its usefulness under these conditions. LITERATURE CITED…”

Effect of clavulanic acid on the activities of ten beta-lactam agents against members of the Bacteroides fragilis group

“…Recently, new 1-lactam antibiotics resistant to hydrolysis by f-lactamase have been introduced (17). Many of these agents, such as ceftizoxime (6, 9) and moxalactam (8), are active against B. fragilis, but other members of the B. fragilis group, especially those producing indole, are much more resistant (12,13,15,20 …”

Diabetic Foot and Gangrene

“…Imipenem, ticarcillin clavulanate and ampicillin -sulbactum all have excellent activity against almost all anaerobic bacteria 21 There is reluctance in using amino glycosides in diabetic patients due to evidence of diabetic nephropathy in these patients and amino glycosides might worsen the nephropathy 22 . The choice of an antipseudomonal agent is likely to be antipseudomonal B-lactam or quinolines.…”