Identification of Pathogenic Bacteria (Escherichia coli) in Drinking Water Sources and Detection of their Antibiotic Resistant Genes in Gampaha District, Sri Lanka

Abstract

Water plays a critical role on Earth, and its significance is particularly evident in relation to human beings. The present study aimed to identification of Escherichia coli and detection of their antibiotic resistant genes in drinking water sources of five different regions Gampaha district, Sri Lanka. Five resources of randomly collect drinking water samples (n = 50) from every 10 samples from five different regions were used for analysis. The pathogenic microorganisms were isolated via membrane filtration technique (0.45 µm) and identified via conventional standard biochemical keys including Indole, Citrate, MRVP, TSI, Motility and Chromogenic culture and Gram stain. The DNA extraction was performed via column-based method. The disk diffusion method was performed to access the antibiotic sensitivity of the isolated Escherichia coli following CLSI guidelines via Ampicillin, Gentamicin and Tetracycline antibiotics (10 mg). From total sample 18% were positive with Escherichia coli in unprotected well, protected well and tap line samples. All nine samples exhibit resistance to Ampicillin (< 13 mm), sensitive to the Gentamicin (> 15 mm) and resistant to Tetracycline (< 11 mm). Molecular determination, 2% agarose gel image, confirmed the presence of E. coli DNA as evidenced by the presence 400 base pairs (bp) band size and UidA gene found in one sample confirmed the presence of different strains of isolated E. coli. The specific antibiotic resistant genes were analyzed and all three samples were negative for the tet (a), tet (C), tet (m) and blaTEM antibiotic resistant genes which confirms that isolated E. coli were not resistant for the Tetracycline and Ampicillin due to mentioned genes.