Étude de la résistance aux antibiotiques des bacilles à Gram négatif isolés des effluents traités de la ville de Tlemcen

Abstract

The presence of multidrug-resistant Gram-negative bacilli in treated wastewater represents a growing concern for both public health and the environment. This study, conducted between March and May 2025 in the Tlemcen region, enabled the isolation of 24 bacterial strains from two sampling sites: the Aïn El Hout wastewater treatment plant (ONA) and the ONID collection basin. Enterobacteria accounted for 58.3% of the isolates, with Klebsiella pneumoniae being the most predominant (57.1%), followed by Escherichia coli (21.4%). Non-fermenting bacilli represented 41.7%, mainly Pseudomonas fluorescens/putida (40%) and Pseudomonas aeruginosa (30%). High resistance rates were observed against several antibiotic families, notably β-lactams, carbapenems, aminoglycosides, and fluoroquinolones. The probable presence of carbapenemases and extended-spectrum β-lactamases (ESBL) in some strains highlights the dissemination of concerning enzymatic resistance mechanisms in treated effluents. These findings underscore the urgent need to strengthen surveillance of reused treated water and to promote the rational use of antibiotics to limit the spread of such resistance in the environment.