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

• Main Authors: Takashi Azuma (Author), Michio Murakami (Author), Yuki Sonoda (Author), Akihiko Ozaki (Author), Tetsuya Hayashi (Author)
• Format: Book
• Published: MDPI AG, 2022-10-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.3390/antibiotics11101355; 2079-6382
• Keywords: antimicrobial-resistant bacteria (AMRB); methicillin-resistant <i>Staphylococcus aureus</i> (MRSA); hospital effluent; sewage treatment plant (STP); river environment; quantitative microbial risk assessment (QMRA); Therapeutics. Pharmacology; RM1-950
• Source: Antibiotics, Vol 11, Iss 10, p 1355 (2022)

The occurrence of <i>Staphylococcus aureus</i> (<i>S. aureus</i>) and methicillin-resistant <i>S. aureus</i> (MRSA) in a sub-catchment of the Yodo River Basin, a representative water system of a drinking water source in Japan, was investigated. The chromogenic enzyme-substrate medium method was used for the detection of <i>S. aureus</i> and MRSA by the presence or absence of antimicrobials in the medium for viable bacteria in a culture-based setting. The contributions of <i>S. aureus</i> and MRSA from wastewater to the rivers were estimated based on mass flux-based analysis, and quantitative microbial risk assessment (QMRA) was further conducted for <i>S. aureus</i> and MRSA in river environments. The mean abundance of <i>S. aureus</i> and MRSA was 31 and 29 CFU/mL in hospital effluent, 124 and 117 CFU/mL in sewage treatment plant (STP) influent, 16 and 13 CFU/mL in STP effluent, and 8 and 9 CFU/mL in river water, respectively. Contribution of the pollution load derived from the target STP effluent to river water ranged from 2% to 25%. The QMRA showed that to achieve the established health benchmarks, the drinking water treatment process would need to yield 1.7 log₁₀ and 2.9 log₁₀ inactivation in terms of infection risk and disability-adjusted life year (DALY) indexes, respectively. These findings highlight the link between medical environment and the importance of environmental risk management for antimicrobial-resistant bacteria in aquatic environments.