A comparison of bacterial community composition in hospital and clinical infections and hospital wastewater treatment systems, and their relative antimicrobial susceptibility and resistance profiles.

This study compared the bacterial community composition of hospital and clinical infections (i.e., biological samples from infected individuals) with that of a hospital wastewater treatment plant (HWTP) (i.e., hospital wastewater samples), focusing on similarities and differences in antimicrobial susceptibility and resistance of these samples. Microbiological analyses, including bacterial identification and antimicrobial susceptibility and resistance testing, were performed according to standardized protocols. An association was observed between hospital-derived isolates and antimicrobial susceptibility, reaching 79.2%, whereas isolates from the HWTP showed a higher association with antimicrobial resistance (41.7%). Resistance rates were pronounced (>30%) across all bacterial groups isolated from the HWTP. Enterobacteriaceae exhibited 34.3% resistance, non-Enterobacteriaceae 52.2%, Streptococcaceae 52.7%, and Micrococcaceae 60.4%. Corresponding susceptibility rates were 50.1%, 36.5%, 26.3%, and 33.3%, respectively. Thus, 15 bacteria strains isolated from hospital/clinic samples and 39 bacteria strains isolated from HWTP samples showed resistance to 3 or more antimicrobials tested. No more than 50% of HWTP isolates were susceptible to the tested antimicrobial agents. In contrast, bacteria isolated from hospital and clinical infections showed overall resistance rates below 10% for each bacterial group. These results highlight the urgent need for more effective hospital wastewater treatment strategies to minimize the emergence and dissemination of antimicrobial resistance.