Microbial Reduction Potential of Chlorine and its Contribution to Incidence of Stress Response Genes in Antibiotic-Resistant Bacteria

Background: The quest for potability of drinking water in various homes led to the widely use of chlorine or chlorine compound in treatment of water. Which however has contributed to increasing incidences of antibiotic resistance in the environment.

Aim: This study aimed to investigate the microbial reduction potential and contribution of Sodium hypochlorite, NaOCl, to incidence of stress response genes in antibiotic-resistant bacteria.

Study Design: Experimental Design was adopted in this study

Place and Duration of the Study: The study was carried out at the Department of Microbiology, Faculty of Science, Ekiti State University between October, 2019 and February, 2020.

Methodology: Sixteen (16) different water samples were randomly collected from various homes in Ajilosun, Ado-Ekiti and were chlorinated following manufacturer’s instruction. Microbial load of both raw and chlorinated water was determined using standard pour plate technique. Standard streaking method was used to isolate bacteria from chlorinated water samples. Standard CLSI technique was used to test the sensitivity of isolates to different antibiotics and PCR technique was employed to detect stress response genes (RpoS, RpoN, KatF genes) in multiple antibiotic-resistant bacterial isolates.

Results: The result showed 24% and 52% reduction in the microbial load of well and pipe-borne water samples respectively following treatment with NaOCl for 180 sec. The different identified bacterial isolates recovered from chlorinated water samples included Enterobacter aerogenes (7.14 %), Proteus vulgaris (10.71 %), Escherichia coli (25 %), Bacillus cereus (32.14 %), Bacillus licheniformis (14.29 %) and Staphylococcus aureus (10.70 %). The bacterial isolates demonstrated varying resistance pattern to the different antibiotics. RpoS, RpoN and KatF genes encoding stress responses were detected in some of the tested antibiotic-resistant isolates.

Conclusion: The study therefore stresses the importance of chlorination in contributing to increasing incidence of resistance of bacteria to stressors in the environment. Hence, subverting chlorination efficacy in treatment of water.