Sink-traps are a major source for carbapenemase-producing Enterobacteriaceae transmission.

OBJECTIVE: We studied the extent of carbapenemase-producing Enterobacteriaceae (CPE) sink contamination and transmission to patients in a nonoutbreak setting. METHODS: During 2017-2019, 592 patient-room sinks were sampled in 34 departments. Patient weekly rectal swab CPE surveillance was universally performed. Repeated sink sampling was conducted in 9 departments. Isolates from patients and sinks were characterized using pulsed-field gel electrophoresis (PFGE), and pairs of high resemblance were sequenced by Oxford Nanopore and Illumina. Hybrid assembly was used to fully assemble plasmids, which are shared between paired isolates. RESULTS: In total, 144 (24%) of 592 CPE-contaminated sinks were detected in 25 of 34 departments. Repeated sampling (n = 7,123) revealed that 52%-100% were contaminated at least once during the sampling period. Persistent contamination for >1 year by a dominant strain was common. During the study period, 318 patients acquired CPE. The most common species were Klebsiella pneumoniae, Escherichia coli, and Enterobacter spp. In 127 (40%) patients, a contaminated sink was the suspected source of CPE acquisition. For 20 cases with an identical sink-patient strain, temporal relation suggested sink-to-patient transmission. Hybrid assembly of specific sink-patient isolates revealed that shared plasmids were structurally identical, and SNP differences between shared pairs, along with signatures for potential recombination events, suggests recent sharing of the plasmids. CONCLUSIONS: CPE-contaminated sinks are an important source of transmission to patients. Although traditionally person-to-person transmission has been considered the main route of CPE transmission, these data suggest a change in paradigm that may influence strategies of preventing CPE dissemination.

Sink traps as the source of transmission of OXA-48-producing Serratia marcescens in an intensive care unit.

BACKGROUND: Carbapenemase-producing Enterobacteriaceae (CPE) outbreaks are mostly attributed to patient-to-patient transmission via healthcare workers. OBJECTIVE: We describe successful containment of a prolonged OXA-48-producing S. marcescens outbreak after recognizing the sink traps as the source of transmission. METHODS: The Sheba Medical Center intensive care unit (ICU), contains 16 single-bed, semi-closed rooms. Active CPE surveillance includes twice-weekly rectal screening of all patients. A case was defined as a patient detected with OXA-48 CPE >72 hours after admission. A root-cause analysis was used to investigate the outbreak. All samples were inoculated on chrom-agar CRE, and carbapenemase genes were detected using commercial molecular Xpert-Carba-R. Environmental and patient S. marcescens isolates were characterized using PFGE. RESULTS: From January 2016 to May 2017, 32 OXA-48 CPE cases were detected, and 81% of these were S. marcescens. A single clone was the cause of all but the first 2 cases. The common factor in all cases was the use of relatively large amounts of tap water. The outbreak clone was detected in 2 sink outlets and 16 sink traps. In addition to routine strict infection control measures, measures taken to contain the outbreak included (1) various sink decontamination efforts, which eliminated the bacteria from the sink drains only temporarily and (2) educational intervention that engaged the ICU team and lead to high adherence to 'sink-contamination prevention guidelines.' No additional cases were detected for 12 months. CONCLUSIONS: Despite persistence of the outbreak clones in the environmental reservoir for 1 year, the outbreak was rapidly and successfully contained. Addressing sink traps as hidden reservoirs played a major role in the intervention.