Wet hospital environments have been documented as potential reservoirs for Carbapenemase-producing Enterobacteriaceae (CPE), possibly contributing to outbreaks among inpatients. Our objectives were to assess the prevalence of CPE reservoirs in a hospital’s wet environments and to investigate the contamination of adjacent dry surfaces.

From March to August 2023, we conducted a cross-sectional study in two hospital wards experiencing ongoing large outbreaks. Sampling of the environment was undertaken in two distinct phases. During phase 1, 38 shower drains and 38 toilet bowls, defined as the wet environment, were sampled using swabs. Phase 2 consisted in sampling adjacent dry surfaces, using wipes in rooms that had tested positive during phase 1. Samples were plated on a selective medium (chromID®CARBASMART, bioMérieux). Species were identified using the matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) technique. Carbapenemases were detected by OKNVI RESIST-5® (CORIS BioConcept).

From the 38 patient rooms, 76 samples were taken during phase 1. All in all, 33 (86.8%) rooms presented at least one CPE reservoir in the wet environment; there were 32 (84.2%) contaminated shower drains and six (15.8%) contaminated toilet bowls. Among 57 identified CPEs, the most frequent strain was Enterobacter cloacae VIM (13, 22.8%). During phase 2, 11 (8.3%) out of 132 samples tested positive for CPE. Enterobacter cloacae complex VIM accounted for six (54.5%) of the CPE strains.

These findings suggest that the wet hospital environments were broadly contaminated with CPE, mostly Enterobacter cloacae VIM. The spread of CPE from wet environments to dry surfaces seemed limited.