ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, June 1985, p. 96-970 Vol. 27, No. 6 0066-4804/85/060968-03$02.00/0 Copyright © 1985, American Society for Microbiology In Vitro Activity of Cefbuperazone Against Bacteroides spp. M. BEATRIZ SOUZA DIAS, NILDA V. JACOBUS, SHERWOOD L. GORBACH, AND FRANCIS P. TALLY* Division ofInfectious Diseases, Department of Medicine, New England Medical Center Hospital, Boston, Massachusetts 02111 Received 9 November 1984/Accepted 14 March 1985 The activity of cefbuperazone was tested in vitro against 287 clinical isolates of Bacteroides spp. Cefbuperazone showed good activity against P. fragils, B. vulgatus, and other Bacteroides species, comparable to that of cefoxitin. It was relatively ineffective against B. distasonis and the B. thetaiotaomicron-ovatus group and was not active against cefoxitin-resistant Barteroides spp. Cefbuperazone (BMY-25182) is a new semisynthetic the B. thetaiotaomicron-ovatus group showed high rates of cephamycin antibiotic. It has a methylthiotetrazole ring at resistance to most ofthe drugs tested, especially to cefbuper- position 3 of the dihydrothiazine ring and a dioxopiperazine azone. Cefotaxime was the most active agent against B. ring as a side chain, a structure similar to those of cefoper- distasonis, and piperacillin was the most active against the azone and piperacillin. In addition, its ,B-lactam ring is B. thetaiotaomicron-ovatus group. Among the B. vulgatus protected against ,B-lactamase activity by the methoxy group strains tested, 83% were susceptible to cefbuperazone, cefox- at position 7 of the P-lactamn ring, as has been shown for itin, moxalactam, cefotaxime, and piperacillin, whereas only other cephamycin compounds (7). The present study com- 50% were susceptible to cefoperazone. Overall, piperacillin, pares the in vitro activity of cefbuperazone with those of cefoxitin, and moxalactam were the most active 1-lactam other third-generation cephalosporins, as well as with those drugs against the B. fragilis group of organisms. Cefotaxime of cefoxitin and piperacillin, against Bacteroides spp. and cefoperazone were much less effective, and cefbuper- Standard antibiotic powders were obtained from the fol- azone occupied an intermediate position between these two lowing sources: cefbuperazone (BMY-25182) from Bristol groups. Laboratories, Syracuse, N.Y.; cefoxitin from Merck & Co., The Bacteroides species population comprised 26 B. biv- Inc., Rahway, N.J.; moxalactam from Eli Lilly & Co., ius, 10 B. melaninogenicus group, 6 B. ureolyticus, 2 B. Indianapolis, Ind.; cefotaxime from Hoechst-Roussel Phar- oris-buccae, 1 B. disiens, and 3 unidentified non-B. frqgilis maceuticals Inc., Somerville, N.J.; cefoperazone from Pfizer group strains, All antibiotics except moxalactam and piper- Inc., New York, N.Y.; and piperacillin from Lederle Labo- acillin inhibited 90%o of the strains of B. bivius and B. ratories, Pearl River, N.Y. Cefbuperazone solution was melaninogenicus at a concentration of 16 Fg/ml. One strain prepared in 1% phosphate buffer immediately before each of B. ureolyticus exhibited multiple resistance to the drugs procedure; all other drugs were diluted in distilled water. studied; this strain was responsible for the high resistance Results are expressed as the MICs for 50 and 90% of the rate of the other Bacteroides species in Table 1. strains tested, the range of variation of MIC, and the percent Resistance to P-lactam antibiotics was examined in 42 resistance to the different antibiotics. The breakpoint for cefoxitin-resistant strains. When low-level resistance to ce- resistance was 32 ,ug/ml for cefbuperazone, moxalactam, foxitin was present (MIC, 32 pxg/ml), 60o of the strains were cefoxitin, cefoperazone, and cefotaxime and 64 ,ug/ml for susceptible to piperacillin, 40o to moxalactam, 37% to piperacillin. The MICs were determined by a modified agar cefotaxime, 27% to cefoperazone, and 17% to cefbuper- dilution method with brain heart infusion agar supplemented azone. When high resistance to cefoxitin occurred (MIC, with vitamin K1 (0.1 mg/ml) and 5% laked sheep erythro- .64 p.s/ml), all of the strains were resistant to the other cytes as described by Tally et al. (14). ,-lactam antimicrobial agents tested. We studied 276 Bacteroides sp. isolates isolated at the Cefbtlperazone was very active against B. fragilis in this Tufts-New England Medical Center Hospital between 1981 study. This species accounted for 58% of the B. fragilis and 1984 or referred to the Tufts Anaerobic Research group isolates collected at the Tufts-New England Medical Laboratory from other hospitals; included were 228 B. Center from 1981 to 1984, a prevalence similar to that fragilis group and 48 other Bacteroides species strains reported by Heseltine et al. (4) at the Los Angeles County- (Table 1). Identification was confirmed according to the University of Southern California Medical Center. How- criteria of the Anaerobe Laboratory Manual of the Virginia ever, the patterns of susceptibility to ,B-lactam drugs among Polytechnic Institute and State University (5). B. ovatus and the various species of the B. fragilis group were remarkably B. thetaiotaomicron were considered in the same group (2). different, as already noted in previous studies (6, 13). In this Twelve strains of the cefoxitin-resistant B. fragilis group report, high resistance was not limited to indole-positive (MIC, .64 ,ug/ml) were included in the study to evaluate the strains, as suggested by Jenkins et al. (6); it was also present activity of the new drug against a highly resistant group of in B. distasonis. This emphasizes the need for identifying organisms. species among Bacteroides sp. isolates and the inadequacy The susceptibility data show that cefbuperazone had good of generalizations regarding antibiotic susceptibility pat- activity against B. fragilis (Table 1). It was as effective as terns. Our data concerning t-lactam susceptibilities of the B. cefoxitin, moxalactam, and piperacillin and more effective fragilis group of organisms parallel those reported in the than cefoperazone and cefotaxime. Both B. distasonis and literature in regard to the comparative potencies of the different drugs, cefoxitin, moxalactam, and piperacillin be- * Corresponding author. ing the most active antibiotics (1, 9-11, 13). 968 VOL. 27, 1985 NOTES 969 TABLE 1. MIC50s, MIC90s, ranges of MICs, and resistance rates for 276 strains of Bacteroides spp. Bacteria (no. of strains tested) Antibiotic MIC (gml)' % Resistant Breakpoint for Range 50 90 strains resistance (.Lg/ml) B. fragilis group (228) Cefbuperazote 0.5->256 8 128 29 32 Cefoxitin 0.5-128 8 32 14 32 Moxalactam <0.1->256 2 64 15 32 Cefotaxime 0.25->256 8 128 34 32 Cefoperazone 1->256 16 64 47 32 Piperacillin 1->256 8 64 11 64 B. fragilis (146) Cefbuperazone 0.5->256 4 16 10 32 Cefoxitin 2-128 8 16 6 32 Moxalactam 0.25->256 1 8 5 32 Cefotaxime 0.5->256 8 64 30 32 Cefoperazone 2->256 16 128 42 32 Piperacillin 0.5->256 4 32 8 64 B. distasonis (12) Cefbuperazone 1->256 128 >256 83 32 Cefoxitin 4-64 16 32 42 32 Moxalactam 0.5->256 32 256 67 32 Cefotaxime 1->256 2 128 17 32 Cefoperazone 2->256 16 128 42 32 Piperacillin 1->256 8 256 25 64 B. thetaiotaomicron-ovatus group (53) Cefbuperazone d.5->256 32 256 70 32 Cefoxitin 1-128 16 32 27 32 Moxalactam 0.5-256 8 128 32 32 Cefotaxime 1->256 32 128 55 32 Cefoperazone 1-256 32 64 62 32 Piperacillin 2->256 8 64 13 64 B. vulgatus (12) Cefbuperazone 2-256 4 128 17 32 Cefoxitin 2-32 4 32 17 32 Moxalactam 0.25-256 1 128 17 32 Cefotaxime 0.25->256 4 64 17 32 Cefoperazone 4->256 16 64 50 32 Piperacillin 1->256 8 256 17 64 B. bivius (26) Cefbuperazone 0.5-32 8 16 8 32 Cefoxitin 0.5-16 2 8 0 32 Moxalactam 0.5-32 4 32 15 32 Cefotaxime <0.1-16 1 8 0 32 Cefoperazone <0.1->256 4 8 0 32 Piperacillin 0.5-32 4 32 0 64 B. melaninogenicus group (10) Cefbuperazone <0.1-8 0.5 8 0 32 Cefoxitin 0.25-8 0.5 8 0 32 Moxalactam 0.25-8 2 8 0 32 Cefotaxime <0.1-8 0.25 2 0 32 Cefoperazone <0.1-8 2 8 0 32 Piperacillin 0.25-16 0.5 16 0 64 Other Bacteroides species (48) Cefbuperazone 0.25-256 4 8 8 32 Cefoxitin <0.1-32 4 16 8 32 Moxalactam <0.1-64 0.25 32 17 32 Cefotaxime <O.1-128 0.5 64 17 32 Cefoperazone <0.1->256 4 64 25 32 Piperacillin <0.1-256 2 16 8 64 a 50% and 90%, MICs for 50 and 90% of the species tested. Previously published data on cefbuperazone by Tai et al. to the 1-lactam antibiotics than were the B. fragilis group of (12) are in disagreement with our results in that these organisms in this and previous reports (11, 14). Cefbuper- investigators have noted the superior activity of cefbuper- azone was as effective as the other 3-lactams against Bac- azone against B. fragilis when compared with cefoxitin. teroides species, whereas a higher resistance rate was reg- However, we all agree that the activity of cefbuperazone is istered for moxalactam. superior to those of cefoperazone and cefotaxime. Cefoxitin resistance among B. fragilis strains has been The Bacteroides species were generally more susceptible attributed to a penetration barrier. More recently, inactiva- 970 NOTES ANTIMICROB. AGENTS CHEMOTHER. tion of this antibiotic by a novel P-lactamase was described ences in susceptibilities of species of the Bacteroides fragilis in our laboratory (3) and by others (15); in at least four of the group to several 3-lactam antibiotics: indole production as an highly cefoxitin-resistant isolates reported, this mechanism indicator of resistance.