Changes in antibiotic resistance patterns of Gram-negative bacilli across three different wastewater treatment plants in northwest Algeria; first comparative study.

Changes in antibiotic resistance of bacteria in three different wastewater treatment plants (WTP) were investigated to determine their role they play in the dissemination of multidrug resistant bacteria (MDR). Water samples were collected from downstream of three (WTP) from where pollution parameters were detected and high-performance Liquid chromatography (HPLC) coupled with an ultraviolet (UV) detector was used to measure antibiotic residues. In addition, 88 bacilli Gram-negative (BGN) were collected; activated sludge, aerated lagoons and natural lagoons, and tested for resistance against 18 βeta-lactam antibiotics. We evaluated the production of Extended-spectrum β-lactamases (ESBLs) in isolates that were further confirmed by applying the automated VITEK-2 system. Among the 88 isolates, Klebsiella pneumoniae (60 %),Escherichia coli (23,33 %) and Serratia marcescens(32,14 %) were the most isolated species. The abundance of the CTX ESBL-producers strains was significantly higher in natural lagoons that may have a greater influence on the occurrence and prevalence of MDR, with the MAR index being the lowest for Serratia marcescens (0,27) and the highest for Citrobacter koseri (0,88), serving as a hotspot environment for the evolution of Antibiotic resistance. Controlling or avoiding this kind of treatment can reduce the chance of MDRs entrance to the environment.