ACTIVITY OF WY-49605 COMPARED WITH THOSE OF AMOXICILLIN, AMOXICILLIN-CLAVULANATE, IMIPENEM, CIPROFLOXACIN, CEFACLOR, CEFPODOXIME, CEFUROXIME, CLINDAMYCIN, AND METRONIDAZOLE AGAINST 384 ANAEROBIC-BACTERIA

The National Committee for Clinical Laboratory Standards agar dilution method was used to compare the in vitro activity of WY-49605 (also ca lled SUN/SY 5555 and ALP-201), a new broad-spectrum oral penem, to tho se of amoxicillin, amoxicillin-clavulanate, imipenem, ciprofloxacin, c efaclor, cefpodoxime, cefuroxime, clindamycin, and metronidazole again st 384 clinically isolated anaerobes. These anaerobic organisms includ ed 90 strains from the Bacteroides fragilis group, 87 Prevotella and P orphyromonas strains, non-B. fragilis group Bacteroides strains, 56 fu sobacteria, 55 peptostreptococci, 49 gram-positive non-spore-forming r ods, and 47 clostridia. Overall, WY-49605 had an MIC range of 0.015 to 8.0 mu g/ml, an MIC at which 50% of the isolates are inhibited (MIC(5 0)) of 0.25 mu g/ml, and an MIC at which 90% of the isolates are inhib ited (MIC(90)) of 2.0 mu g/ml. Good activity against all anaerobe grou ps was observed, except for Clostridium difficile and lactobacilli (MI C(50)s of 4.0 and 2.0 mu g/ml, respectively, and MIC(90)s of 8.0 and 2 .0 mu g/ml, respectively). Imipenem had an MIC(50) of 0.03 mu g/ml and an MIC(50) of 0.25 mu g/ml. Ciprofloxacin was much less active (MIC(5 0) of 2.0 mu g/ml and MIC(90) of 16.0 mu g/ml). By comparison, all ora l beta-lactams were less active than WY-49605, with susceptibilities a s follows: amoxicillin MIC(50) of 8.0 mu g/ml and MIC(90) of > 256.0 m u g/ml), amoxicillin-clavulanate MIC(50) of 1.0 mu g/ml and MIC(90) of 8.0 mu g/ml, cefaclor MIC(50) of 8.0 mu g/ml and MIC(90) of > 32.0 mu g/ml, cefpodoxime MIC(50) of 4.0 mu g/ml and MIC(90) of > 32.0 mu g/m l, and cefuroxime MIC(50) of 4.0 mu g/ml and MIC(90) of > 32.0 mu g/ml . Clindamycin was active against all groups except some members of the B. fragilis group, Fusobacterium varium, and some clostridia (overall MIC(50) of 0.5 mu g/ml and overall MIC(90) of 8.0 mu g/ml). Metronida zole was active (MIC of less than or equal to 4.0 mu g/ml) against all gram-negative anaerobic rods, but most gram-positive non-spore-formin g rods, some peptostreptococci, and some clostridia were less suscepti ble. To date, WY-49605 is the most active oral beta-lactam against ana erobes: these results suggest clinical evaluation for clinical indicat ions suitable for oral therapy.