2004 Volume 52 Issue 1 Pages 17-22
We determined the MIC50 and MIC90 of four carbapenem antibiotics, i. e., imipenem (IPM), panipenem (PAPM), meropenem (MEPM), and biapenem (BIPM), for 125 strains of Pseudomonas aeruginosa isolated from clinical specimens between April 1999 and March 2002. The MIC50 and MIC90 values obtained were: 1 μ g/mL and 16μg/mL, respectively, for IPM, 4, ug/mL and 16 gemL, respectively, for PAPM, 0.5μg/mL and 8μg/mL, respectively for MEPM, and 0.5 Etig/mL and 8μg/mL, respectively, for BIPM. The results indicated that the antibiotic efficacy of BIPM and MEPM was superior to that of IPM and PAPM. The acute bactericidal action of the carbapenem antibiotics was markedly enhanced by the addition of fresh human serum to a final concentration of 50%, but the bactericidal effect of the cephem derivative ceftazidime (CAZ) was not significantly affected by fresh human serum. Neutrophils obtained from healthy adults were exposed to P. aeruginosa strain MSC-399 that had been incubated in the culture medium containing each of the four carbapenem antibiotics at 1/4 the MIC. The chemiluminescence index (CL index) of the neutrophils exposed to BIPM was 1.91, and significantly higher than that of the cells exposed to IPM, PAPM, or MEPM and the control cells (p<0.05). The results suggest that added to bacterial culture medium BIPM is the most potent of the carbapenems in stimulating the phagocytotic and bactericidal activity of neutrophils exposed to P. aeruginosa.
