Serogrouping, plasmid and drug resistance of Pseudomonas aeruginosa in Taiwan.
The Pseudomonas aeruginosa isolates in Taiwan were grouped with antisera against O antigens and tested with 13 different antimicrobial agents. Group E (28%) lead in serogrouping, followed by Group G (19%), Group F (16%), Group B and Group H (12%, respectively), and there were no significant differences in distribution of serogroups among the isolates from different areas in Taiwan. Amikacin (75%) and piperacillin (74%) were the most effective antibiotics, followed by tobramycin (63%), carbenicillin (62%), ticarcillin (57%) and gentamicin (56%). Group F strains were relatively more susceptible to most of the antibiotics tested than strains of other serogroups. All strains tested were multiple drug resistance. Thirty percent (67/224) of P. aeruginosa carried plasmids. The average number of resistant markers per strain was 8.7 for plasmid-carrying strains as compared to 7.6 for plasmid-free strains. The plasmid-carrying strains showed higher drug resistance than plasmid-free strains. Twenty-seven percent (13/48) of plasmid-carrying strains contained R plasmids which were detected by transformation (6/23) and conjugation (7/25). These R plasmids totally encoded at least seven different resistant markers. The R plasmid from P. aeruginosa 119 was not modified after transforming into Escherichia coli RR1. The R plasmids of P. aeruginosa transferred into E. coli RR1 or Serratia marcescens 73 caused some changes in the outer membrane of transformants or transconjugants. Some R plasmid-carrying strains and their transformants or transconjugants exhibited the ability to produce acetyltransferase.