[The antimicrobial susceptibilities and serotypes of Pseudomonas aeruginosa isolated from sputum].

During the period of January 1992 and August 1995, 75 strains of Pseudomonas aeruginosa were isolated from sputum at the Hiroshima Prefectural Hiroshima Hospital. The antimicrobial susceptibilities and serotypes of those strains were investigated. The results are summarized as follows: 1. The analyses of antimicrobial susceptibilities revealed that meropenem (MEPM) was the most active among the carbapenems tested against those P. aeruginosa strains with MIC of < or = 6.25 micrograms/ml. All of the strains were thus found to be susceptible to MEPM, while 9 strains out of 75 (12%) were resistant to imipenem showing cross-resistance to biapenem. 2. The activities of the beta-lactams other than carbapenems were found to be the order of cefozopran > or = ceftazidime > aztreonam > piperacillin with MIC50 and MIC90 ranging of 3.13-6.25 micrograms/ml and 25- > or = 100 micrograms/ml, respectively. 3. Among aminoglycosides tested, 3 strains (4.0%) of the strains showed resistance to amikacin, however none of them were resistant to tobramycin. 4. Distribution of serotypes among the strains was; type G 22.7%, type M 21.3%, type A 16.0%, type B 13.3% and type E 8.0%. Strains of types M and E showed multiple resistance to beta-lactams except carbapenems. As documented in this study, the frequency of isolation of beta-lactam-resistant P. aeruginosa (including carbapenem-resistant) is steadily increasing. Continuous surveillance of antimicrobial susceptibility among clinically isolated P. aeruginosa seems to be necessary.