Detection of pathogenic E. coli O157 along with the chemical monitoring of coastal water from Sarakkuwa to Mirissa coastal belt in Sri Lanka

Abstract

Escherichia coli is considered as an indicator of fecal contamination and is found in gastrointestinal tracts of warm-blooded animals. E. coli O157 is a pathogenic serotype that produces intimin and shiga-toxins and responsible for severe health circumstances. Recreational activities heighten the infection risk of E. coli O157 to the human gut through contaminated waters. The objective of this study is to detect E. coli O157 strain and to determine chemical water quality parameters from Sarakkuwa to Mirissa coastal belt, Sri Lanka. The virulent genes eae, stx1 and stx2 were selected for the screening of E. coli O157. The PCR amplification was carried out through standardized protocols. The chemical water quality parameters; N-nitrate, N-nitrite, N-ammonia, and total phosphate were measured following the APHA standard methods. Results showed that all water samples were contaminated with E. coli and CFU values ranged between 5.00 ± 5.29 and 157 ± 2.00. E. coli of Dehiwala, Mt. Lavinia, Rathgama, and Galle areas showed positive results for eae gene while Ambalangoda, Hikkaduwa, Rathgama, and Weligama areas showed positive results for stx1 gene. Galleface, Mt. Lavinia, Ginthota, Unawatuna, Koggala, and Mirissa areas were positive for stx2 gene. Altogether, E. coli O157 strain was detected in 12 out of 22 sampled locations. The recorded N-nitrate, N-nitrite, N-ammonia, and total phosphate of the study sites ranged within 0.30 - 4.03 mg/L, 0 - 0.64 mg/L, 2.39 - 0.03 mg/L, 0.06 - 3.17 mg/L respectively. The presence of E. coli O157 indicates the unsuitability of water for recreation and findings emphasize that continuous monitoring and legislation are essential to upholding the water quality of the studied coastal stretch.