Prevalence of Opportunistic Pathogens and Diversity of Microbial Communities in the Water System of a Pulmonary Hospital

Abstract

Objective: Our objective was to investigate the occurrence of opportunistic pathogens and characterize the bacterial community structures in the water system of a pulmonary hospital.

Methods: The water samples were collected from automatic and manual faucets in the consulting room, treatment room, dressing room, respiratory ward, and other non-medical rooms in three buildings of the hospital. Quantitative polymerase chain reaction was used to quantify the load of several waterborne opportunistic pathogens and related microorganisms, including Legionella spp., Mycobacterium spp., and M. avium. Illumina sequencing targeting 16S rRNA genes was performed to profile bacterial communities.

Results: The occurrence rates of Legionella spp., Mycobacterium spp., and M. avium were 100%, 100%, and 76%, respectively in all samples. Higher occurrence rates of M. avium were observed in the outpatient service building (building 1, 91.7%) and respiration department and wards (building 2, 80%) than in the office building (building 3), where no M. avium was found. M. avium were more abundant in automatic faucets (average 2.21 × 10 ⁴ gene copies/L) than in manual faucets (average 1.03 × 10 ⁴ gene copies/mL) ( P < 0.01). Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, and Acidobacteria were the dominant bacterial phyla. Disinfectant residuals, nitrate, and temperature were found to be the key environmental factors driving microbial community structure shifts in water systems.

Conclusion: This study revealed a high level of colonization of water faucets by opportunistic pathogens and provided insight into the characteristics of microbial communities in a hospital water system and approaches to reduce risks of microbial contamination.

Keywords: Hospital water system; Microbial community; Mycobacterium avium; Opportunistic pathogen.