7432-s and cefetamet

MICs of 21 beta-lactams were determined by agar dilution against 283 penicillin-susceptible (pen-S), 122 intermediate (pen-I) and 23 fully penicillin-resistant (pen-R) pneumococci. MICs of all beta-lactams increased with increasing MICs of penicillin. Clometocillin was the most active penicillin against pen-I or pen-R pneumococci. All oral cephalosporins except cefuroxime and cefpodoxime were less active than penicillin and none was satisfactory against pen-I or pen-R pneumococci. The parenteral third- and fourth-generation cephalosporins (except ceftazidime) were similar in activity to penicillin against pen-S isolates. Cefpirome showed the lowest mean MICs against pen-I and pen-R strains.

Topics: Amoxicillin; Ampicillin; Anti-Bacterial Agents; beta-Lactams; Carbapenems; Cefaclor; Cefadroxil; Cefatrizine; Cefepime; Cefixime; Cefotaxime; Cefpirome; Cefpodoxime; Ceftazidime; Ceftibuten; Ceftizoxime; Ceftriaxone; Cefuroxime; Cephalosporins; Cephradine; Drug Resistance, Microbial; Drug Resistance, Multiple; Humans; Microbial Sensitivity Tests; Penicillin Resistance; Penicillins; Piperacillin; Pneumococcal Infections; Serotyping; Species Specificity; Streptococcus pneumoniae

In order to provide additional data on the in vitro antibacterial activity of cefetamet-pivoxil against respiratory pathogens, we determined the bactericidal kinetics of this antibiotic in comparison to cefixime and ceftibuten against H. influenzae, M. catarrhalis, K. pneumoniae, E. coli, S. pneumoniae and S. pyogenes. time-kill studies were performed by using concentrations equal to a x MIC, and 4 x MIC of the antibiotics tested and different inocula (10(5), 10(7) and 10(9) CFU/ml). The strains were incubated in a shaking incubator at 37 degrees C and 1 ml samples were removed at regular intervals for viable count determination. The antibiotics were eliminated by serial ten-fold dilutions in physiological saline before plating. At 4 x MIC of cefetamet and at 10(5) CFU/ml inoculum the results were 99.9% killing or more of H. influenzae and M. catarrhalis at 4 h, and of E. coli and K. pneumoniae within 4 to 6 h, and of E. coli and K. pneumoniae within 4 to 6 h. At the same concentration of MIC and with the same inoculum a 99.9% reduction was achieved against S. pneumoniae within 4 h and against S. pyogenes within 2 h with no regrowth at 24 h in both cases. Similar results were obtained using 10(7) and 10(9) CFU/ml inocula. Cefetamet had efficient killing activity even at lower concentrations. Bactericidal kinetics of cefetamet favorably compare with those of cefixime and ceftibuten. The efficient bactericidal activity of cefetamet-pivoxil indicates a clinical role for this new oral cephalosporin in the treatment of respiratory tract infections.

Topics: Administration, Oral; Cefixime; Cefotaxime; Ceftibuten; Ceftizoxime; Cephalosporins; Escherichia coli; Haemophilus influenzae; Kinetics; Klebsiella pneumoniae; Microbial Sensitivity Tests; Moraxella catarrhalis; Streptococcus pneumoniae; Streptococcus pyogenes

A multilaboratory study was performed to establish broth microdilution MIC quality control (QC) guidelines for 10 investigational drugs which previously demonstrated significant activity against Haemophilus influenzae. MIC QC ranges for H. influenzae ATCC 49247 with Haemophilus test medium were determined by using multiple contemporary lots of Haemophilus test medium and the National Committee for Clinical Laboratory Standards' recommended numbers of replicate tests. On the basis of these results, QC ranges (generally modal MIC +/- one log2 dilution) are proposed for cefdinir, cefepime, cefetamet, cefpirome, ceftibuten, fleroxacin, temafloxacin, clarithromycin, RP59500, and trospectomycin. The proposed QC guidelines for clarithromycin and temafloxacin were recently accepted by the National Committee for Clinical Laboratory Standards.

Topics: Anti-Bacterial Agents; Cefdinir; Cefpirome; Ceftibuten; Ceftizoxime; Cephalosporins; Clarithromycin; Erythromycin; Fleroxacin; Fluoroquinolones; Haemophilus; Humans; Microbial Sensitivity Tests; Quality Control; Quinolones; Spectinomycin; Virginiamycin