Environmental contamination by carbapenem-resistant Enterobacteriaceae

Abstract

In the last decade, the global emergence of carbapenem resistance in Enterobacteriaceae has posed great concern to public health. Data concerning the role of environmental contamination in the dissemination of carbapenem-resistant Enterobacteriaceae (CRE) are currently lacking. Here, we aimed to examine the extent of CRE contamination in various sites in the immediate surroundings of CRE carriers and to assess the effects of sampling time and cleaning regimens on the recovery rate. We evaluated the performance of two sampling methods, CHROMAgar KPC contact plate and eSwab, for the detection of environmental CRE. eSwab was followed either by direct plating or by broth enrichment. First, 14 sites in the close vicinity of the carrier were evaluated for environmental contamination, and 5, which were found to be contaminated, were further studied. The environmental contamination decreased with distance from the patient; the bed area was the most contaminated site. Additionally, we found that the sampling time and the cleaning regimen were critical factors affecting the prevalence of environmental CRE contamination. We found that the CHROMAgar KPC contact plate method was a more effective technique for detecting environmental CRE than were eSwab-based methods. In summary, our study demonstrated that the vicinity of patients colonized with CRE is often contaminated by these organisms. Using selective contact plates to detect environmental contamination may guide cleaning efficacy and assist with outbreak investigation in an effort to limit the spread of CRE.

Fig 1

Locations of testing for environmental CRE (eCRE). 1, personal bedside table; 2 to 4, bed linen around the pillow (2), crotch (3), and legs (4); 5, pulse oximeter; 6, personal bedside chair; 7, electrical outlet line; 8, manual respirator bag; 9, infusion pump; 10, dedicated stethoscope; 11, ventilator; 12, suction machine; 13, cardiovascular monitor screen; 14, enteral feeding pump.

Fig 2

Recovery rates (% positive samples) of environmental CRE (eCRE) from the patients' surroundings. (A) The effect of the 3 sampling-cultivation methods on the recovery rate of eCRE. CP, CHROMAgar KPC contact plates; ES, eSwab sampling, direct plating onto CHROMAgar KPC plates; ESBB, eSwab sampling, broth enrichment prior to plating; (B) The recovery rates of eCRE from 5 different sites in the vicinity of the carriers: pillow, crotch, legs, personal bedside table, and infusion pump. (C) The effect of sampling time on the recovery rate of eCRE. Morning and noon samples were done before and 4 h after clothing and sheet replacement, respectively. (D) The recovery rate of eCRE from two wards at TASMC.