Antibiotic Resistant Escherichia coli Isolated from Faecal Samples of Cow at Livestock Farm in Kedah, Malaysia

Abstract

Introduction: Escherichia coli is a typical microflora found in the intestines of livestock, but regular exposure to antibiotics puts them under selection pressure to acquire antibiotic resistance. This study aimed to identify and characterise the antibiotic resistance profile of E. coli isolated in cow faeces collected from Tobiar Modern farm located in Kedah, Malaysia. Materials and methods: The antibiotic susceptibility test (AST) was conducted to assess the sensitivity of E. coli isolates to tetracycline (30 µg/mL), erythromycin (15 µg/mL) and ampicillin (10 µg/mL) using disk diffusion method followed by Minimum Inhibitory Concentration (MIC) assay. For molecular identification of selected resistant isolates, 16S rDNA gene sequencing was carried out. Results: Six (Isolates A1, P1, P2, P3, P4, and P5) out of 30 isolates were identified as E. coli based on their colonial morphological characteristics. The tests for catalase, indole, MR, TSI, and lactose fermentation all yielded positive results for the isolates, whereas the tests for oxidase, citrate, and VP yielded negative results. All six isolates were found to be erythromycin resistant. The Isolate P4 was observed as a multidrug resistant (MDR) bacterial strain since it exhibited resistance to all tested antibiotics. The MDR Isolate P4 is identified as E. coli strain LWY24 using molecular identification with a 99.7% identity rate. Conclusion: This study offers important preliminary information on the incidence of antibiotic-resistant bacteria (ARB) on this particular local livestock farm. This data is useful for developing plans to reduce the prevalence of ARB in livestock.