The relationship between the daily dosage of the carbapenem meropenem (MEPM) and MEPM-resistant Pseudomonas aeruginosa

Pseudomonas aeruginosa is a pathogen which is known to be responsible for nosocomial infection. The appropriate use of antibiotics has become important for preventing the spread of drug-resistant P. aeruginosa. In Hara-doi Hospital, two carbapenem antibiotics, imipenem (IPM) and meropenem (MEPM), are used for patients aged 65 years or older at a daily dosage of 1.0 g and 0.5 g, respectively. Of P. aeruginosa samples isolated in 2003, the sensitivity to IPM was 54% and to MEPM it was 58%. In 2004, the sensitivity to IPM was 55%, i.e., not significantly different from 2003. In 2004, the daily dosage of MEPM was increased to 1.0 g/day, and the sensitivity to MEPM increased to 71%. Based on the Pharmacokinetics/Pharmacodynamics (PK/PD) theory, even though the patients were elderly, a sufficient dosage of antibiotics given over a shorter period of time was effective against MEPM-resistant P. aeruginosa in a hospital ward, and there were no side effects.