Inactivation of Bacteria and Residual Antimicrobials in Hospital Wastewater by Ozone Treatment

Abstract

The emergence and spread of antimicrobial resistance (AMR) has become a persistent problem globally. In this study, an ozone treatment facility was established for an advanced hospital wastewater treatment in a core hospital facility in an urban area in Japan to evaluate the inactivation of antimicrobial-resistant bacteria and antimicrobials. Metagenomic DNA-seq analysis and the isolation of potential extended-spectrum β-lactamase (ESBL)-producing bacteria suggested that ozone exposure for at least 20 min is required for the adequate inactivation of DNA and ESBL-producing bacteria. Escherichia coli and Klebsiella species were markedly susceptible to 20-min ozone exposure, whereas Raoultella ornithinolytica and Pseudomonas putida were isolated even after an 80-min exposure. These ozone-resistant bacteria might play a pivotal role as AMR reservoirs in the environment. Nine antimicrobials (ampicillin, cefdinir, cefpodoxime, ciprofloxacin, levofloxacin, clarithromycin, chlortetracycline, minocycline, and vancomycin) were detected at 373 ng/L to 27 μg/L in the hospital wastewater, and these were removed (96–100% removal) after a 40-min treatment. These results facilitate a comprehensive understanding of the AMR risk posed by hospital wastewater and provides insights for devising strategies to eliminate or mitigate the burden of antimicrobial-resistant bacteria and the flow of antimicrobials into the environment. To the best of our knowledge, this is the first report on the implementation of a batch-type, plant-scale ozone treatment system in a hospital facility to execute and evaluate the inactivation of drug-resistant bacteria and antimicrobials.

Comprehensive Genome and Plasmidome Analysis of Antimicrobial Resistant Bacteria in Wastewater Treatment Plant Effluent of Tokyo

“…Urban WWTP effluents could be a potential source of AMR burden. Therefore, there is concern that hospital [ 19 ] and community [ 20 ] effluents include a considerable proportion of ARGs in the environment. Among potential healthy EPB carriers, globally disseminated E. coli ST131 clones should first be investigated.…”

Occurrence and Quantitative Microbial Risk Assessment of Methicillin-Resistant Staphylococcus aureus (MRSA) in a Sub-Catchment of the Yodo River Basin, Japan

“…In addition, due to the presence of a wide variety of live microorganisms in activated sludge in the biological treatment reactors at STPs [ 79 ], there have been concerns that AMRB could result in a pool of AMRB through zygotic transmission or transformation [ 80 , 81 , 82 ]. One of the measures to overcome these challenges is to introduce advanced water treatment systems such as ozonation [ 83 , 84 , 85 ], membrane processes [ 86 , 87 ], UV [ 64 , 88 ], electrochemical [ 89 , 90 ], and peracetic acid [ 91 , 92 ] treatments that may effectively decrease the levels of these new environmental pollutants in the wastewater discharged into the river environment.…”

Performance of a Pilot-Scale Continuous Flow Ozone-Based Hospital Wastewater Treatment System

“…An ozone inactivation system for bacteria and antimicrobials present in hospital wastewater based on a continuous flow system was installed at the University Hospital, Ohashi Medical Center (BN; 35.652578 • N, 139.683959 • E), with a capacity of 319 beds, in Toho University, Tokyo, Japan, as previously reported [21]. Various wastewaters generated as a result of hospital activities were stored in two underground wastewater tanks (influent) with a total volume of 22.5 m 3 .…”

“…Previous studies have reported antimicrobial-resistant bacteria (ARB) as a problem in clinical practice, suggesting that hospital wastewater may serve as a reservoir for AMR [15][16][17][18][19]. In addition to ARB, residual antimicrobials can be detected in hospital effluents [12,20,21]. The pollution load of hospital wastewater in aquatic environments ranges from several tens to 71%, with rates varying by country [22][23][24][25][26].…”

“…A medium-scale batch-type treatment tank (effective volume of 1 m 3 ) was installed in the hospital to evaluate the inactivation effect of ozone treatment on ARB and antimicrobials. Both ARB and residual antimicrobials were reduced to ≤1% after 20 min of treatment [21]. If the wastewater treatment of a hospital on a practical scale is proven to be a feasible solution to environmental AMR concerns, it may be conceived as an effective mechanism against AMR, thus contributing to the One Health initiative [32,53,54].…”