[Isolation and characterization of gentamicin resistance plasmids of coliform bacteria from the waste water of a water treatment plant].

Gentamicin resistance coliforms detected continuously in raw and purified waste water samples of a sewage treatment plant made up less than 0.1% of all coliforms. 43.9%; 31.4%; 13.3% and 11.3% of gentamicin-resistant coliforms were identified as Enterobacter, E. coli, Klebsiella and Citrobacter, respectively. R plasmids encoding a gentamicin resistance phenotype were isolated and characterized. They range between 55 and 60 MD in size and belong to 3 incompatibility groups (IncOF, IncM, IncK). Using restriction endonucleolytic digestion of plasmids, they could be further characterized and subtyped. In contrast to moderate molecular alterations observed among the IncM plasmids, the IncOF plasmids reveal a high stability of restriction pattern. This IncOF plasmid was predominantly found in E. coli wild strains and detected continuously.