Risk of Transmission of Imipenem-Resistant Pseudomonas aeruginosa through Use of Mobile Bathing Service

Objectives：The demand for mobile bathing service (MBS) is increasing in the Japanese society. Therefore, we assessed the risk of MBS-associated infection in MBS clients and their caregivers by examining the bacterial colonization of MBS equipment and utensils. Methods：Bacterial isolates collected by the stamp agar culture method were examined by disk diffusion assay for their susceptibility to the following drugs：imipenem, ciprofloxacin, amikacin, azutreonam, ceftazidim, meropenem, piperacillin, tobramycin, ofloxacin and cefoperazone. Furthermore, these isolates were subtyped by Spel-pulsed field gel electrophoresis (SpeI-PFGE). Results：Fifty-four P aeruginosa isolates were recovered from different sampling sites, and of these, 26 (47.3%) were isolated from pillows. Eighteen isolates (33.3%) were imipenem (IPM) resistant. The minimum inhibitory concentrations (MICs) of 17 isolates were between 16 and 32 μg/ml, and the MIC of one isolate was greater than 32 μg/ml. The SpeI-PFGE typing of IPM-resistant isolates revealed that 13 of the 18 isolates were closely related (F=1.0-0.87). Conclusion：Our findings suggest that MBS equipment and utensils, particularly pillows, are the primary sources of bacterial contamination and transmission and that there is a risk of MBS-mediated infection among MBS clients and their caregivers.