Persistent environmental reservoirs for Vancomycin-resistant enterococci requiring repeated decontamination to achieve eradication

Abstract

V ancomycin-resistant enterococci (VRE) are increasingly recognised nosocomial pathogens in clinical areas with high antibiotic usage. Patients with chronic renal failure, including those requiring haemodialysis, are at particular risk. Investigation and control of an outbreak of VRE in two renal wards, highlighting mattresses as reservoirs and environmental measures to control VRE are reported in this paper. Outbreak control measures included standard isolation in accordance with the Recommendations of the Hospital Infection Control Practices Advisory Committee (HICPAC). Patients were screened on admission and weekly using a rectal swab. The inanimate environment including mattresses was also screened. Enhanced environmental decontamination was performed on a daily basis.

The outbreak continued over a 20-week period with most cases occurring in the first 6 weeks. The results of screening indicated that 59 (13%) of 451 patients and 54 (8.3%) of 647 environmental samples were positive for VRE. VRE was isolated from 35 (8%) of 433 mattresses, 12 (8.1%) of 148 environmental ledges, 4 (8%) of 50 toilets, and 3 (18.8%) of 16 items of cleaning equipment. Molecular typing indicated that a predominant strain was also implicated in mattress contamination, thus highlighting a potential and important reservoir for transmission of VRE. Difficulty with eradication of VRE from the environment was encountered despite enhanced cleaning regimens and a doubling of use of disinfectant was necessary.

Restriction of antibiotics, hand hygiene, hygiene and education are the cornerstone of VRE prevention and control. Lessons from this outbreak highlight the role of the environment in VRE transmission and the need for attention to the environment, especially mattress decontamination.