Antibacterial Activity of Azadirachta Indica Leaf Extracts Against Extended Spectrum Betalactamase Producing Escherichia Coli Isolated from Raw Cow Milk: A One Health Approach

Abstract

Emergence of drug resistance in Escherichia coli harboring extended spectrum betalactamase (ESBL) genes in both humans and animals is of major concern to global health. Antimicrobial resistance (AMR) has escalated due to the inappropriate use of antimicrobials in humans, animals, and the environment. This study aimed to evaluate the antibacterial activity of aqueous and ethanolic Azadirachta indica leaf extracts against ESBL producing Escherichia coli isolated from raw cow milk, incorporating a One Health perspective to address antibacterial resistance in human, animals and environmental health contexts. Raw milk samples (n=100) were collected from different locations within Keffi, Nasarawa state.  The presence of Escherichia coli was investigated using cultural, morphological and biochemical technique. The presence of different ESBL resistance genes (blaTEM, blaSHV, blaCTX-M  groups) in E. coli isolates were evaluated both phenotypically using double-disc synergy test (DDST) and genotypically using polymerase chain reaction (PCR) technique. Azadirachta indica (neem) leaves were extracted using two solvents (water and ethanol). Different concentrations of aqueous and ethanolic leaf extracts were used to detect their efficacy against ESBL producers. The results demonstrated that 30 (30%) of the isolates were contaminated with E. coli. The most resistant antibiotics among the isolates was amoxicillin-clavulanic acid (96.7%) and the least resistant was gentamicin (23.3%). The most frequently occurring MAR indices ranged from 0.8 (16.7%) - 0.9 (23.3%) and the least occurring MAR index is 0.2 (6.7%). ESBL production was detected in 9 out of the 30 isolated E. coli using Double Disc Synergy Test (DDST). 4 out of the 9 ESBL producers were confirmed to express resistance genes (blaTEM, blaCTX-M, blaCTX-M-1 and blaCTX-M-4). The ethanolic leaf extracts of neem plant had antibacterial potential against ESBL Escherichia coli but only at very high concentration of the extracts. Therefore, it could be a potential natural alternative or a partner drug in the treatment of infections caused by ESBL Escherichia coli transmitted to humans or animals. The results call for multisectoral One Health strategies that combine veterinary, environmental and public health efforts to control the dissemination of antimicrobial resistance from animal sources to humans ensuring food safety and the effectiveness of the antibiotics.