Sources of sporadic Pseudomonas aeruginosa colonizations/infections in surgical ICUs: Association with contaminated sink trap

Background: Many studies have reported the hospital outbreaks of Pseudomonas aeruginosa due to cross-contamination between patients and water fittings, but the importance of water fittings as sources of sporadic P. aeruginosa colonizations/infections remains ambiguous.

Aim: To investigate the sources of sporadic P. aeruginosa colonizations/infections in a clinical intensive surveillance, and further analysis the potential of sink trap for P. aeruginosa transmission in intensive care units (ICUs).

Methods: Patients monitoring and targeted environmental screening for P. aeruginosa was performed prospectively over a 27-week period, in absence of recognized outbreak, in two surgical intensive care units (SICUs). All isolates were genotyped by Pulsed field gel electrophoresis analysis.

Findings: 18.9% (46/244) of water fitting samples harbored P. aeruginosa, and active screening samples from 9.2% (55/595) of hospitalized patients carried with P. aeruginosa. According to genotype results, approximately 50% of P. areuginosa colonizations/infections of patients were of exogenous origin. 64.7% (11/17) of exogenous sourced cases were associated with contaminated sink traps. There was a significant correlation between the incidence of exogenous colonization/infection and the prevalence of P. areuginosa in water fitting in SICU-2 (rs = 0.972; p = 0.014). Furthermore, P. areuginosa from sink trap possessed a higher level of resistance to multi-antibiotics as opposed to cross-transmission from other patients.

Conclusion: Water fitting especially sink trap act as an important role in sporadic P. aeruginosa transmission in SICU patients. This report highlights the necessity of identification of potential environmental reservoirs, such as sinks, for control of infections of environmentally hardy multi-resistant P. areuginosa.