Quantitative Microbial Risk Assessment of Antimicrobial Resistant and Susceptible Staphylococcus aureus in Reclaimed Wastewaters

Abstract

The annual risks of colonization, skin infection, bloodstream infection (BSI), and disease burden from exposures to antibiotic-resistant and susceptible Staphylococcus aureus (S. aureus) were estimated using quantitative microbial risk assessment (QMRA). We estimated the probability of nasal colonization after immersion in wastewater (WW) or greywater (GW) treated across a range of treatment alternatives and subsequent infection. Horizontal gene transfer was incorporated into the treatment model but had little effect on the predicted risk. The cumulative annual probability of infection (resulting from self-inoculation) was most sensitive to the treatment log10 reduction value (LRV), S. aureus concentration, and the newly calculated morbidity ratios and was below the health benchmark of 10–4 infections per person per year (ppy) given a treatment LRV of roughly 3.0. The predicted annual disability-adjusted life years (DALYs), which were dominated by BSI, were below the health benchmark of 10–6 DALYs ppy for resistant and susceptible S. aureus, given LRVs of 4.5 and 3.5, respectively. Thus, the estimated infection risks and disease burdens resulting from nasal colonization are below the relevant health benchmarks for risk-based, nonpotable, or potable reuse systems but possibly above for immersion in minimally treated GW or WW. Strain-specific data to characterize dose–response and concentration in WW are needed to substantiate the QMRA.

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

“…The risk of infection and disability-adjusted life years (DALYs) per person per year (ppy) for daily exposure to water for domestic use for one year was calculated according to a previous study [ 27 ]. Briefly, the risk assessment of skin or bloodstream infections due to water use was performed separately for MRSA and methicillin-susceptible S. aureus (MSSA).…”

“…In this study, QMRA was performed as per a method described in a previous study [ 27 ], with some modifications. It should be noted that the methodology used in this paper was based on limited data but is currently available.…”

“…It should be noted that the methodology used in this paper was based on limited data but is currently available. Horizontal gene transfer was not considered because it has negligible effects on the results as per a previous study [ 27 ]. The S. aureus concentrations in water were assumed to follow a lognormal distribution based on the measurements in this study.…”

“…This approach has been applied for indicator microorganisms [ 25 ] and, more recently, for COVID-19 [ 26 ]. Furthermore, QMRA of methicillin-susceptible S. aureus and MRSA in reclaimed wastewater is recently being conducted as a case study on risk assessment for AMRB [ 27 , 28 ]. Under these circumstances, it would be possible to quantitatively assess the environmental risk caused by AMRB in aquatic environments and the effectiveness of countermeasures to reduce and/or eliminate the risk of applying this method.…”

Integrating Environmental Dimensions of “One Health” to Combat Antimicrobial Resistance: Essential Research Needs

“…The development of high-throughput culturomics, functional metagenomics, and biofilm assays in in vivo animal and human exposure studies will aid in the elucidation of mechanisms underlying host–microbe interactions and host responses. The mechanisms of transmission to colonization and infection need to be translated into the strain-specific infectious dose of a certain ARB to advance quantitative assessments of microbial risk. , Such a framework should contain both culture-dependent and culture-independent measurements to include under-appreciated resistance phenotypes. A quantitative microbial risk assessment framework incorporating the aggregate exposure pathways, infectious dose, and effect mechanisms of colonization and infection is also in line with the well-established risk assessment framework for chemical pollutants, thus contributing to the development of a human exposome framework.…”