Tracking Carbapenem-Resistant Pathogens in Hospital Wastewater: the focus on Acinetobacter baumannii and Pseudomonas aeruginosa
Carbapenem-resistant Pseudomonas aeruginosa (CRPA) and Acinetobacter baumannii (CRAB) represent a major clinical and epidemiological challenge and pose a growing threat to public health and the environment. Accordingly, CRPA and CRAB were investigated in hospital wastewater (HWW) collected during winter and summer 2024 from 64 healthcare facilities across all 16 Polish voivodeships. To our knowledge, this study constitutes the first nationwide, large-scale assessment in Poland of carbapenem resistance in these high-risk pathogens in hospital wastewater. The study aimed to determine the prevalence of carbapenem-resistant bacteria (CRB) in HWW discharged into the public sewer system and municipal wastewater treatment plants (WWTPs). In addition, associations between CRB prevalence, hospital geographic location, and sampling season were analyzed to identify spatial and temporal patterns of carbapenem resistance (CR). Carbapenem-resistant P. aeruginosa were predominant in all studied regions. Carbapenem-resistant A. baumannii were identified in a smaller percentage of samples and were characterized by greater genotypic diversity. The ERIC-PCR assay confirmed the presence of both closely related strains and unique genetic profiles, which suggests that CRB emissions into the environment have a complex character. The statistical analysis revealed significant relationships between CRB counts, the physicochemical parameters of HWW, and antibiotic concentrations in HWW samples. In addition, the tested samples harbored many antibiotic resistance genes (ARGs), which confirms that HWW is a significant reservoir of mobile genetic elements (MGEs) involved in the spread of antibiotic resistance. The results of the study indicate that HWW should be rigorously monitored and managed to minimize risks to public health and environment.