Prevalence And Antimicrobial Resistance Escherichia Coli And Salmonella Bacteria Isolated From Cultyred Shrimp And Pond Water

Abstract

Antibiotics play a key role in controlling bacterial infections of shrimps. This study investigated the Antibiotic Sensitivity Testing (AST) of Escherichia coli and Salmonella from shrimp samples taken from seven shrimp farms in Puttalam District, Sri Lanka. Twenty-one cultured shrimp samples were analysed and thirteen E. coli and nrne Salmonella cultures were isolated. Antibiotic sensitivity for isolated bacterial cultures was tested using the Kirby-Bauer disc diffusion method. The antibiotic susceptibility pattems of these bacterial species were assayed against five antibiotics including amoxicillin (30 mcg), oxltetracycline (30 mcg), chloramphenicol (1Omcg), erythromycin (10 mcg), and tetracycline (10 mcg). The diameter of inhibition zones was compared with Clinical and Laboratory Standards Institute standards. Among the 2I shrimp samples, 53.84% (7113) of E. coli rsolates were highest resistant to erythromycin, and 38.46% exhibited resistance towards ambxicillin and tetracycline with susceptibility towards chloramphenicol. Additionally, E. coli cultures isolated from pond water samples showed resistance towards erythromycin and tetracycline at a rate of 33 .33%. All Salmonella isolates in shrimp samples showed 44.44% (419),wtth the highest resistance to erythromycin and llJl% (Il9), lower resistance to tetracycline and amoxicillin, while they showed the highest susceptibility to chloramphenicol and oxytetracycline. Moreover, E. coli and Salmonella isolates from pond water displayed resistance to erythromycin. E. coli isolates from shrimp samples were found to have a Multiple Antibiotic Resistance (MAR) index of as high as 0.8 with the antibiotic combination of amoxicillin, erythromycin, oxytetracycline and tetracycline. These results showed that antibiotic-resistant bacteria are present in shrimp farms.