Hospital Wastewater Sludge: An Unaddressed Environmental Reservoir for Emerging and Rare Nosocomial Pathogens

Abstract

Nosocomial infections cause significant mortality and financial losses each year. Most of these infections are caused by multidrug resistant (MDR) opportunistic pathogens and therefore are difficult to treat by standard therapies. Though hospitals are considered as ecological niches for nosocomial pathogens, environmental reservoirs for the same are still underexplored. The present study addressed this issue by systematically profiling the pathogenic diversity of hospital wastewater sludge hypothesized as an important reservoir for nosocomial pathogens within a hospital setting using Illumina Miseq Next Generation Sequencing (NGS) approach. The NGS data showed that i) nosocomial pathogens dominated the hospital sludge bacterial profile and majority of them fell in the category of either emerging or rare pathogens ii) Majority of the pathogens formed part of the low abundant microbiota represented by 3.56% of the reads iii) Nearly 14% of the reads were represented by the unculturable bacteria iv) Of the 580 species-level operational taxonomic units (OTUs) identified in this study, 166 matched with potential human pathogens v) Enterobacter cloacae (56.45%) was the most dominant species followed by  Pseudomonas putida (6.07%), Fusobacterium ulcerans (3.08%) Acidaminococcus fermentans (2.03%) respectively. Aeromonas hydrophila, Klebsiella pneumoniae and Pantoea agglomerans formed the less dominant species. This study points towards the catastrophic effect on public health and environment that may result from the co-treatment of hospital wastewater with domestic wastewater in municipal wastewater treatment plants and the use of resultant sludge in agriculture which is a common method of sludge disposal practiced in developing countries.

Keywords: Hospital sludge, Next Generation Sequencing, Nosocomial Pathogens, Emerging Pathogens, Rare Pathogens