Carbapenem Resistance Among Gram-Negative Bacteria in Bioaerosols at Biomedical Waste Disposal Site in Ahmedabad, India

Antimicrobial resistance (AMR) is a global public health concern, with Gram-negative carbapenem-resistant bacteria (CRG) classified by WHO as critical priority pathogens. Biomedical waste disposal sites (BMWs) may act as reservoirs for resistant organisms, posing occupational and community risks. This study investigated the phenotypic and genotypic characterization of Gram-negative carbapenem-resistant bacteria in bioaerosols collected from BMW facilities in Ahmedabad, Gujarat, India. Bioaerosols were sampled using active Six-stage Andersen Impactors and passive settled plates. Isolates were identified by MALDI-TOF, followed by antimicrobial susceptibility testing (AST). Whole genome sequencing (WGS) was performed for 26 representative isolates, and resistance gene profiling was conducted using CARD and ResFinder databases. Representative isolates belonged to Moraxellaceae, Enterobacteriaceae, and Pseudomonadaceae families. All species showed resistance to linezolid, and approximately 60% were multidrug resistant to carbapenems, cephalosporins, and fluoroquinolones. Genotypic analysis confirmed the prevalence of carbapenemase genes, with blaNDM-1 most frequent, followed by blaNDM-7, blaVIM-2, blaVIM-11, blaOXA-23, and blaOXA-235. This is the first report documenting Acinetobacter baumannii, A. schindleri, A. towneri, Klebsiella pneumoniae, and Pseudomonas juntendi in bioaerosols from BMW sites. Biomedical waste environments serve as critical reservoirs of AMR. These findings emphasize the need for surveillance, protective measures, and integration of environmental AMR monitoring into public health policy.