Characterization of Carbapenem-Resistant and ESBL-Producing Enterobacterales in Wastewater and Sludge Environments from Northern Spain
Source abstract
Abstract
Wastewater treatment plants (WWTPs) are recognized hotspots for the convergence and dissemination of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs) into the environment. Among ARB, carbapenem-resistant Enterobacterales (CR-E) and extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae (ESBL-Ec/Kp) are of particular concern due to their clinical relevance. We characterized 30 CR-E and 176 ESBL-Ec/Kp isolates (two of them were both ESBL-producing and carbapenem-resistant) recovered from influent, intermediate, effluent, sludge, and downstream river samples collected from two WWTPs in northern Spain. Isolates were evaluated for resistance phenotypes against 12 antimicrobials, and β-lactamase-encoding genes were assessed by PCR and sequencing. Notably, among CR-E isolates, blaKPC-2 was the most prevalent (93%), followed by blaOXA-48-like, detected in two isolates from non-treated and pasteurized sludge; both isolates also carried blaCTX-M-15, a finding not previously reported specifically in sludge samples. Among ESBL-Ec/Kp, a broad diversity of ESBL genes was identified, including blaCTX-M group 1 (variants 1, 3, 15, 32, 55), blaCTX-M group 9 (variants 14, 27, 65, 97), blaSHV-12 and blaTEM-169. The most prevalent ESBL gene was blaCTX-M-15 (48.3%), followed by blaCTX-M-14, blaCTX-M-32, and blaSHV-12, detected in 10.8%, 8.5%, and 6.8% of isolates, respectively. CR-E and ESBL-Ec/Kp were found in all sample types and were still detectable at terminal stages, indicating persistence throughout treatment. These findings support the need to improve and optimize current wastewater treatment methods and underscore the importance of integrating culture-based and molecular methods into routine WWTP monitoring for early detection of microbiological hazards, although further research is still needed.
Source: crossref · Quality: baseline
Research context
OpenAlex topics: Antibiotic Resistance in Bacteria · Pharmaceutical and Antibiotic Environmental Impacts · Infections and bacterial resistance
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Area of Biochemistry and Molecular Biology, OneHealth-UR Research Group, University of La Rioja, 26006 Logroño, Spain
Funding
ADER-UR
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