The antibacterial activity of meropenem (MEPM) and other parenteral antibiotics against clinical isolates of 2655 strains including 810 strains of Gram-positive bacteria, 1635 strains of Gram-negative bacteria, and 210 strains of anaerobic bacteria obtained from 30 medical institutions during 2009 was examined. The results were as follows;

1. MEPM was more active than the other carbapenem antibiotics tested against Gram-negative bacteria, especially against enterobacteriaceae and Haemophilus influenzae. MEPM was also active against most of the species tested in Gram-positive and anaerobic bacteria, except for multi-drug resistant strains including methicillin-resistant Staphylococcus aureus (MRSA).

2. MEPM maintained potent and stable antibacterial activity against Pesudomonas aeruginosa. The proportion of MEPM-resistant strains to ciprofloxacin-resistant strains or imipenem-resistant strains were 53.1% and 58.0% respectively.

3. The proportion of extended-spectrum β-lactamase (ESBL) strains was 3.1% (26 strains) in enterobacteriaceae. And the proportion of metallo-β-lactamase strains was 2.0% (6 strains) in P. aeruginosa.

4. Of all species tested, there were no species except for Bacteroides fragilis group, which MIC₉₀ of MEPM was more than 4-fold higher than those in our previous study. Therefore, there is almost no significant decrease in susceptibility of clinical isolates to meropenem.

In conclusion, the results from this surveillance study suggest that MEPM retains its potent and broad antibacterial activity and therefore is a clinically useful carbapenem for serious infections treatment at present, 14 years passed after available for commercial use in Japan.

Recently, there have been reports concerning an increased frequency of isolation of multi-drug resistant Pseudomonas aeruginosa (MDRP) strains in hospitals and other clinical settings as well as the associated risk of their hospital-acquired infections; in such a situation, it has been a major challenge to establish methods of managing and treating the infections. In order to investigate the trend of P. aeruginosa, the Infection Forum in the Chugoku Region has conducted to a multi-center collaborative study to isolate P. aeruginosa strains from sputum and urine samples collected between October 2006 and September 2008, analyzed the drug susceptibility and the pulsed-field gel electrophoresis (PFGE) patterns of each strain, and assessed epidemiologic characteristics.

Of the 738 P. aeruginosa strains collected in this study, 152 (20.6%), 179 (24.3%), 47 (6.4%), and 39 (5.3%) were found to be ciprofloxacin-resistant, imipenem-resistant, amikacin-resistant, and MDRP, respectively. Among the various antimicrobial agents tested, arbekacin (ABK) revealed the strongest inhibitory effects on each drug-resistant and MDRP strain; therefore, ABK was considered as a potential candidate for future treatment of diseases caused by P. aeruginosa.

The study also showed that the detection rates of MDRP varied a lot from hospital to hospital. In addition, PFGE-based cluster analyses revealed several strains isolated in the same hospital exhibited a similar PFGE pattern and the same drug susceptibility, suggesting the presence of “unique” hospital-specific strains.

The linezolid treatment for methicillin-resistant Staphylococcus aureus (MRSA) infection was sporadically reported in children. Here we describe a case of a 6 month-old patient underwent mediastinal drainage and artificial conduit removement caused by MRSA infection. After that, linezolid treatment was started and bacteremia was resolved after 14 days of treatment. At discharge, he was no febrile, his blood culture were sterile. We report a case of a patient with MRSA endocarditis treatment with linezolid.