Susceptibilities of 200 penicillin-susceptible and -resistant pneumococci to piperacillin, piperacillin-tazobactam, ticarcillin, ticarcillin-clavulanate, ampicillin, ampicillin-sulbactam, ceftazidime, and ceftriaxone.
MICs of eight beta-lactams (piperacillin, piperacillin-tazobactam, ticarcillin, ticarcillin-clavulanate, ampicillin, ampicillin-sulbactam, ceftazidime, and ceftriaxone) were determined by agar dilution against 64 penicillin-susceptible, 70 intermediately penicillin-resistant, and 66 fully penicillin-resistant pneumococci. The MICs of piperacillin with and without tazobactam for 90% of the susceptible, intermediately resistant, and resistant strains tested (MIC90s) were < or = 0.064, 2.0, and 4.0 micrograms/ml, respectively. By comparison, those of ampicillin with and without sulbactam were 0.125, 2.0, and 4.0 micrograms/ml and those of ceftriaxone were < or = 0.064, 1.0, and 2.0 micrograms/ml, respectively. Strains were less susceptible to ticarcillin with and without clavulanate (MIC90s, 2.0, 64.0, and 128.0 micrograms/ml) and ceftazidime (MIC90s, 1.0, 8.0, and 32.0 micrograms/ml).
Pankuch
G A
GA
Department of Pathology (Clinical Microbiology), Hershey Medical Center, Pennsylvania 17033.
Jacobs
M R
MR
Appelbaum
P C
PC
D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002442:Ceftazidime / Q000494:pharmacology; D002443:Ceftriaxone / Q000494:pharmacology; D002969:Clavulanic Acids / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D010397:Penicillanic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D010403:Penicillin Resistance; D010878:Piperacillin / Q000494:pharmacology; D013296:Streptococcus pneumoniae / Q000187:drug effects*; D013407:Sulbactam / Q000494:pharmacology; D000078142:Tazobactam; D013982:Ticarcillin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D002969:Clavulanic Acids; C035444:sultamicillin; D002443:Ceftriaxone; D000667:Ampicillin; C043215:ticarcillin-clavulanic acid; D010397:Penicillanic Acid; D002442:Ceftazidime; D013982:Ticarcillin; D013407:Sulbactam; D000078142:Tazobactam; D010878:Piperacillin