Susceptibility of clinically isolated strains of bacteria to carbapenem- related antibiotics

The susceptibility of clinically isolated strains of bacteria to carbapenem-related antibiotics, such as panipenem (PAPM), meropenem (MEPM), and imipenem (IPM), was evaluated according to the Kirby-Bauer method (KB method); the selection criteria for these antibiotics were thus examined. There was no difference in the susceptibility rate of four bacteria, E. coli, MSSA, MRSA, and S. epidermidis to PAPM, MEPM and IPM. The sensitivity of P. aeruginosa to the three drugs was MEPM = IMP > PAPM. Enterococcus had low drug susceptibility (17.1%) to MEPM, moderate drug susceptibility (51.2%) to PAPM, and high susceptibility (82.9%) to IPM. The susceptibility of Enterococcus was IPM > PAPM > MEPM. Probable cross-resistance among the three antibiotics was suggested to E. coli, MRSA, S. epidermidis, P. aeruginosa and Enterococcus. The three carbapenem-related antibiotics examined showed no differences in their susceptibility to E. coli, MSSA and S. epidermidis. For drug selection, pharmacokinetics and other factors should be taken into account for these clinically isolated bacteria. Since these three drugs are not indicated for MRSA, it was considered desirable to select MEPM or IPM against P. aeruginosa, and PAPM or IPM for Enterococcus.