Association between contaminated faucets and colonization or infection by nonfermenting gram-negative bacteria in intensive care units in Taiwan

Abstract

This study was designed to determine the strength of the association between the isolation of nonfermentative gram-negative bacilli (NFGNB) from tap water faucet aerators and the prevalence of colonization or infection of patients in intensive care units (ICUs). Surveillance cultures were obtained during a 4-month period from 162 faucet aerators located in seven different ICUs. The prevalence of colonization or infection of ICU patients with NFGNB was determined by prospective surveillance during the same period. Fifty four (33%) of the faucet aerators contained NFGNB. Among the 66 NFGNB isolated from faucet aerators, the most frequently encountered ones were Sphingomonas paucimobili (26 isolates), Pseudomonas aeruginosa (14 isolates), Chryseobacterium meningosepticum (13 isolates), Achromobacter xylosoxidans (6 isolates), Burkholderia cepacia (4 isolates), and Stenotrophomonas maltophilia (3 isolates). Acinetobacter baumannii was not recovered. The most common NFGNB isolated from ICU patients were P. aeruginosa and A. baumannii. There was a significant correlation between the overall prevalence of NFGNB in faucet aerators and their prevalence in exposed ICU patients (Spearman r = 0.821, P = 0.02). There was also a significant correlation between the prevalence of C. meningosepticum in faucet aerators and its prevalence among ICU patients (Spearman r = 0.847, P = 0.016). The electrokaryotypes of four clinical isolates of C. meningosepticum were similar to those of faucet isolates. Measures directed at making the water supply safe may prevent infection by C. meningosepticum and other waterborne pathogens.

FIG. 1.

Correlation between faucet aerator contamination rates and infection or colonization prevalence rates in patients in different ICUs due to (A) NFGNB described in Table 1 (correlation coefficient r = 0.821, P = 0.02) and (B) C. meningosepticum (r = 0.847, P = 0.016).

FIG. 2.

(A) Electrokaryotypes of C. meningosepticum isolates digested by the restriction enzyme ApaI and analyzed by PFGE for 22 h with pulse intervals ranging from 1 to 15 s. Lane 1, DNA size marker; lanes 2, 4, 8, 9, 11, and 12, clinical isolates (isolates P80, L70, AL51, AS74, P81, and L39 in panel B); lanes 3, 5, 6,7, and 10, faucet isolates. The karyotypes of four clinical isolates (lanes 2, 4, 8, and 9) were similar to those of faucet isolates (lanes 3, 5, 6, and 7, respectively). (B) Phylogenetic tree of C. meningosepticum isolates collected from the faucet survey and from patients. The karyotypes of faucet isolates are shaded in gray.

FIG. 3.

(A) Electrokaryotypes of P. aeruginosa isolates digested with the restriction enzyme SpeI and analyzed by PFGE for 24 h with pulse intervals ranging from 0.2 to 40 s. The faucet isolates (lanes 1 to 6) and clinical isolates (lanes 7 to 12) were different. Lane 13 was a DNA size marker. (B) Phylogenetic tree of P. aeruginosa isolates collected in the faucet survey and from patients. The pulsotypes of faucet isolates are shaded in gray.