Hideaki Miwa

Occurrence of PER-1 Producing Clinical Isolates of Pseudomonas aeruginosa in Japan and their Susceptibility to Doripenem

The acquisition of resistance by extended-spectrum β-lactamases (ESBL) has been reported primarily for Enterobacteriaceae, but there are few reports on the isolation of ESBL-producing Pseudomonas aeruginosa. PER-1-type ESBL producing P. aeruginosa has been found in various regions around the world but there are no reports of clinical isolates in Japan. During our susceptibility surveillance studies over a 10 year period, we found four clinical isolates resistant to ceftazidime due to production of PER-1. They were resistant to ceftazidime but susceptible in the presence of clavulanic acid, a class A β-lactamase inhibitor. The strains had the ability to hydrolyze ceftazidime. They also had the gene for PER-1-type ESBL. This is the first report of the isolation of PER-1 producing strains in Japan. These four strains were resistant to ceftazidime, cefepime and aztreonam with MICs of 64 μg/ml or more, but were more susceptible to carbapenem antibiotics. In particular, doripenem, which is a novel carbapenem antibiotic, showed good antibacterial activity with a MIC of 2 or 4 μg/ml, which was more potent than meropenem and imipenem. Doripenem also showed good therapeutic efficacy against a systemic infection of mice with a PER-1 producing strain, and was also more potent in vivo than imipenem or meropenem.

A new type of ketolides bearing an N-aryl-alkyl acetamide moiety at the C-9 iminoether synthesis and structure-activity relationships.

A new type of ketolides, bearing an N-aryl-alkyl acetamide moiety at the C-9 iminoether and a cyclic carbonate at the C-11,12 position was prepared and the antibacterial activities of the compounds were evaluated. Some of the derivatives showed potent antibacterial activity against both Haemophilus influenzae and Streptococcus pneumoniae, which are clinically important respiratory tract pathogens. Among the derivatives prepared, compound 5s with a quinolin-4-yl moiety was found to have potent and well-balanced activity against S. pneumoniae and H. influenzae including erythromycin-resistant strains.