The Risk of Radio-Resistance Development in Wild-Type Salmonella enterica serotype Typhimurium Isolated from Chicken Carcass Towards Gamma Irradiation Treatment

Abstract

Salmonella enterica serotype Typhimurium (S. Typhimurium) is a foodborne pathogen whose presence in foods should be avoided. Food preservation methods such as gamma irradiation can eliminate S. Typhimurium without compromising food quality. However, as S. Typhimurium's resistance to irradiation increases, there is a possibility of treatment failure, which coincides with a public health problem. The objective of this study was to characterize the sensitivity of wild-type S. Typhimurium isolated from chicken carcasses in Surabaya's wet market toward gamma irradiation treatment, as part of a radio-resistant S. Typhimurium monitoring.Using a conventional Salmonella isolation methodology, S. Typhimurium was recovered from chicken carcasses sold at Surabaya's wet market. The selected isolate was then subjected to a biochemical test, followed by serological and PCR confirmation. The S. Typhimurium isolate suspension was irradiated with a 0 to 0.4 kGy dose using a cobalt-60 panoramic batch irradiator (1.1 kGy/h dosage rate). The viable colonies of an irradiated isolate were counted, and the D₁₀ value was calculated by plotting the number of irradiated isolates per initial isolate number (0 kGy radiation) versus the dose. Four S. Typhimurium isolates from chicken carcasses sold in Surabaya's wet market showed varying slopes of a linear regression derived from viable cell enumeration results. As a result, the computed D₁₀ value differed for each isolate. KS 1 SC III had the lowest D₁₀ value (0.09 kGy), followed by PK 2 SC I (0.14 kGy) and PK 3 SC I (0.15 kGy), while KS 3 SC V had the greatest value (0.19 kGy).The radio-sensitivity of the isolate varied according to the D₁₀ value, which ranged from 0.09 to 0.19 kGy. Simply stated, it shows that radio-resistance development has occurred in wild-type S. Typhimurium. Despite being unclear, varied stress exposure to wild-type S. Typhimurium was identified as the most potentially impacting factors; nonetheless, further research is required for this purpose.

Keywords:   Irradiation, Resistance, Salmonella, Typhimurium