Molecular Detection of Carbapenemase Genes in Clinical Isolates and Hospital Wastewater in Ogun State: Implications for Environmental Dissemination

Hospital wastewater serves as a critical nexus for antibiotic resistance gene dissemination into the broader environment, yet its role in carbapenemase gene transmission in Nigerian settings remains unstudied. This analytical study detected and characterized carbapenemase genes in clinical isolates and hospital wastewater from Olabisi Onabanjo University Teaching Hospital, Sagamu, Ogun State, in the South West geopolitical zone of Nigeria. Clinical Gram-negative isolates from 120 patients and wastewater samples collected at influent, effluent, and receiving stream points were processed. Carbapenemase phenotype was confirmed by the modified carbapenem inactivation method. Carbapenemase gene detection used multiplex PCR targeting blaKPC, blaNDM, blaOXA-48-like, blaVIM, and blaIMP genes. Clinical isolates demonstrated 28.3 percent carbapenem non-susceptibility. blaNDM-1 was the predominant gene in clinical isolates at 52.9 percent, followed by blaOXA-48-like at 35.3 percent. Identical carbapenemase gene sequences were detected in wastewater effluent and clinical isolates, and NDM-positive isolates were recovered from the receiving stream. Wastewater effluent showed no carbapenemase gene reduction relative to influent, indicating negligible gene removal by existing treatment. These findings demonstrate active environmental seeding of carbapenemase genes by hospital wastewater in Ogun State and strongly advocate for advanced wastewater treatment technology, environmental monitoring of resistance genes, and a comprehensive One Health resistance surveillance network. Keywords: carbapenemase genes, hospital wastewater, blaNDM, Ogun State, environmental dissemination.