Gram Negative Bacterial Diversity and Antimicrobial Resistance Profiles in Heavily Polluted Environmental Samples around The Sır Dam Lake (Turkey)

Abstract

Background: The Sır Dam Lake is located on the Ceyhan River and provides a major water-supply to agricultural fields in Southern Turkey. However, it has so far received various industrial and household wastes in excessive amounts. Aims: This study aims to analyze Gram negative bacterial diversity and antimicrobial resistance profiles in polluted environmental samples (soil, sludge, water) collected around the Dam Lake. Study Design: Gram negative bacteria were isolated from 15 polluted environmental samples and identified using both phenotypic and molecular methods. In addition, antimicrobial resistance profiles of the strains were determined by disk diffusion method. Place and Duration of Study: Environmental samples were collected from 15 different locations in Avsar region located around the Sır Dam Lake in March 2014. Methodology: Gram negative bacterial strains were identified based on biochemical tests. Biochemical identification of the bacterial isolates was further verified using CHROMagar ECC (France). A fragment corresponding to 16S rRNA gene was amplified using universal primers. The sequence analyses of amplified fragments were used for molecular identification of unidentified isolates by biochemical tests. Antimicrobial susceptibilities of the isolates were determined with disk diffusion method. Results: A total of 17 identified strains were grouped as Escherichia coli (n=8), non-fermenters (n=5) and Enterobacteriaceae (n=4). Only two strains (Klebsiella oxytoca and Enterobacter spp.) were identified from Enterobacteriaceae. Acidovorax temperans emerged as the second predominant bacteria following to E. coli and did not display significant resistance to the tested antimicrobials. However, most of E. coli isolates as well as a single K. oxytoca and a single Acinetobacter spp. isolates displayed higher multiple antimicrobial resistance (MAR) index values that should be considered seriously for local public health. Conclusion: Gram negative bacterial distribution remarked the presence of fecal contamination. In addition, the presence of A. temperans might indicate a presence of different types of pollution, and this organism might be useful in biodegradation processes after its metabolic capability is defined.