Can environmental contamination be explained by particular traits associated with patients?

SUMMARY Background Little is known about patient risk factors associated with environmental contamination. Aim To evaluate the rate of environmental contamination and to investigate individual risk factors. Methods A prospective cohort study was conducted. Each day, five rooms occupied by patients were selected. Five critical surfaces were systematically swabbed twice a day before and after cleaning. Clinical characteristics of all patients were collected. Logisitic regression was performed to evaluate the association between environmental contamination and patients' characteristics. Findings A total of 107 consecutive patients were included and 1052 environmental samples were performed. Nineteen (18%) patients were known previously colonized/infected with a multidrug-resistant organism (MDRO). Respectively, 723 (69%) and 112 (11%) samples grew with ≥1 and >2.5 cfu/cm2 bacteria, resulting in 62 (58%) contaminated rooms. Considering positive samples with at least one pathogenic bacterium, 16 (15%) rooms were contaminated. By univariate and multivariate analysis, no variables analysed were associated with the environmental contamination. Considering contaminated rooms with >2.5 cfu/cm2, three factors were protective for environmental contamination: known MDRO carriers/infected patients (odds ratio: 0.25; 95% confidence interval: 0.09–0.72; P = 0.01), patients with urinary catheter (0.19; 0.04–0.89; P = 0.03) and hospitalization in single room (0.3; 0.15–0.6; P Conclusion This study was conducted in a non-outbreak situation and showed a low rate of environmental contamination with pathogenic bacteria. Only 11% of environmental samples grew with >2.5 cfu/cm2, and they were related to non-pathogenic bacteria. No risk factors associated with environmental contamination were identified.