Role of Sinks as an Environmental Reservoir in CPE Outbreak in a Burn Intensive Care Unit

Background The incidence of carbapenemase- producing enterobacteriacae (CPE) is steadily increasing in health care settings. Sink drains have been identified as a reservoir for transmission of CPE. We describe a CPE outbreak in a burn intensive care unit (ICU), where we identified CPE contaminated sink drains as the most likely source of transmission. Methods The surveillance and infection control measures undertaken to contain the outbreak included weekly microbiological screening, environmental sampling of sink drains, shower drains, ice machine, and hydrotherapy hoses. Plasmid analysis was performed on the patient isolates. Results There were 3 nosocomial Klebsiella pneumoniae carbapenemase-producing (KPC) cases identified between September and November 2019 including 2 bloodstream infections. The first case was not on the unit at the same time as the two subsequent cases. Plasmid analysis of the three cases revealed that they were identical. As part of outbreak control measures, admission to the unit was restricted, staff were cohorted to care for CPE positive and negative patients, and CPE positive patients were geographically separated to one side of the unit. Polymerase chain reaction (PCR) testing of sink drain swabs identified 3 KPC positive sinks. One of the sinks was epidemiologically linked to the cases. No other water sources tested positive. Retrospective case reviews and four-weekly point prevalence identified no additional cases. Conclusions The outbreak investigation shows that CPE positive sink drains were likely implicated in the transmission of this CPE outbreak especially given the absence of any patient source on the unit during the first transmission. This outbreak re-affirms the role that contaminated water sources play in CPE transmission and the importance of sink design and other engineering solutions to prevent dispersion of CPE from ICU sink drains.