Study on the ecological characteristics of environmental bacteria, and selection of a simple and easy genotyping method for the tracking their sources and disseminating routes in the hospitals.

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Initially, we investigated the relation between biofilm formation, an ecological characteristic of environmental bacteria, and sensitivity against disinfectants using Pseudomonas aeruginosa(Ps). The main findings are summarized as follows.1.Ps could be isolated from as much as 21 places from 29 places including water-plug and drainage areas in the nurse station, and urinal-washing and bath areas.2.Teflon-sheet test, in which biofilm-forming sessile cells (SC) is distinguished from floating cells(FC), showed that biofilm was detected in all strains including 21 environmental isolates and 10 clinical isolates except one environmental isolates.3.Disinfectant(benzethonium chloride and chlorhexidine digluconate)-sensitivity test showed that survival rates of SC are significantly higher than those of FC.4.The higher survival rates of SC is shown more clearly in the clinical isolates, suggesting that recontamination of health-care environments with the clinical isolates should be avoided.Secondly, we compared three genotyping methods, random amplified polymorphic DNA polymerase chain reaction method(RAPD-PCR) using three different primers(pr 1 to 3), pursed field gel electrophoresis method(PFGE) and infrequent restriction site PCR method(IRS-PCR), to select a simple and easy one for the infection control nurses(ICN) using 16 stains of Serracia marcescens (Sm). The main findings are summarized as follows.1.16 strains were distinguished to 15 types, 13 types, 9 types and 7 types in the RAPD-PCR (pr 1), RAPD-PCR(pr 2) and PFGE, IRS-PCR, and RAPD-PCR(pr 3), respectively.2.These data indicate that strain-distinguishing efficiency of RAPD-PCR is almost comparable to that of PFGE if an appropriated primer is constructed. However, RAPD-PCR has more merits than PFGE from the aspects of time consumption (2 days versus 7 days) and simplicity.3.In summary, RAPD-PCR should be recommended for ICN to search the sources and disseminating routes of hospital-acquired infection.