title: Resistance plasmids of Pseudomonas aeruginosa: change from conjugative to nonconjugative in a hospital population.
abstract: Properties of a population of carbenicillin- and gentamicin-resistant, tobramycin-susceptible Pseudomonas aeruginosa at Veteran's Administration Hospital, Cincinnati, Ohio, have been followed during a 16-month period. As originally described, the strains were isolated from patients with urinary tract colonizations and were predominantly Parke-Davis immunotype 7. For the majority of these organisms, antibiotic resistance was correlated with the presence of a self-conjugative plasmid of incompatibility group P-2. The source and relative incidence of multiply resistant isolates have remained constant during the current study, but the immunotype has shifted form type 7 to type 2. Concomitantly, the population has lost the property of conjugative transfer of resistance, and resistant strains are now compatible with P-2 plasmids. A group P-2 R plasmid, pMG5, will mobilize resistance markers, demonstrating that the multiple resistance of the nonconjugative strains is mediated by R plasmids. Additionally, gentamicin resistance due to either conjugative or nonconjugative plasmids is correlated with the presence of similar gentamicin acetyltransferase activity. pMG5-mobilized plasmids are shown to be incompatible with pMG5. pMG5 is also shown to mobilize resistance markers from nontransferring antibiotic-resistant strains representing populations from Parkland Memorial Hospital, Dallas, Texas, and Cleveland Clinic Foundation, Cleveland, Ohio.
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism; D003227:Conjugation, Genetic; D003428:Cross Infection / Q000382:microbiology; D003470:Culture Media; D004352:Drug Resistance, Microbial; D005111:Extrachromosomal Inheritance; D005839:Gentamicins / Q000494:pharmacology; D006801:Humans; D010957:Plasmids; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000201:enzymology; D014552:Urinary Tract Infections / Q000382:microbiology
chemical_list: D003470:Culture Media; D005839:Gentamicins; D000123:Acetyltransferases