A long-lasting Sphingomonas paucimobilis outbreak: A potential for pathogens to persist on environmental devices despite disinfection measures

•Sphingomonas paucimobilis is an aerobic, non-fermentative, Gram-negative opportunistic bacillus.•The outbreak persisted for nearly 2 years despite all necessary preventive measures.•A potential for pathogens to persist on environmental devices.•Individual tracking of all devices used in critical care settings with records of pre- and post-disinfection procedures is of paramount importance. Sphingomonas paucimobilis, an aerobic, non-fermentative, Gram-negative opportunistic bacillus, can colonize everywhere in hospital settings where water is used. We reported a hospital S paucimobilis outbreak that persisted for nearly 2 years despite all necessary preventive measures. Over a period from February 13, 2020 to December 3, 2021, 67 patients were identified to have S paucimobilis as documented by positive cultures from clinical samples, along with 19 positive environmental samples. Bacterial regrowth for molecular analysis could be obtained in 49 isolates (39 clinical, 4 extracorporeal membrane oxygenation (ECMO) water heater devices, 1 unused mouthwash solution, 5 water samples from thoracic drainage aspirators). Two distinct clonally indistinguishable genotypes were detected in AP-PCR and PFGE analyses, with 100% consistency. The main cluster was obtained consistently throughout the outbreak from 30 samples (61.2%: 24 clinical, 4 ECMO, 1 unused mouthwash solution, 1 water sample from the thoracic drainage aspirator). The other cluster involved 15 clinical samples and 4 water samples from the thoracic drainage aspirators. Given that waterborne pathogens can spread to a wide range of equipment used in healthcare environments, the pathogens can persist on the surfaces of environmental devices even after recommended disinfection measures have been applied. Therefore, individual tracking of all devices used in critical care settings, such as thoracic drainage aspirators and ECMO water heater devices, with records of pre- and post-disinfection procedures is of paramount importance for complete elimination of the source of infection.