Effectiveness of radiation processing in elimination of Klebsiella pneumoniae from food

Klebsiella pneumoniae is a cause of community-acquired bacterial pneumonia, and also as an emerging opportunistic pathogen that causes severe morbidity and mortality among the new-borne and immuno-compromised persons. Foods such as fish, raw vegetables, infants feeds and ready to eat foods have been reported to be contaminated with Klebsiella spp. Radiation processing is one of the best methods to ensure microbial safety without affecting nutritional and organoleptic quality of food. Studies were carried out to determine radiation sensitivity of K. pneumoniae in different foods like sprouts, chicken and fish. The decimal reduction dose (D₁₀) value of Klebsiella pneumoniae MTCC 109 in saline, nutrient broth, mixed sprouts, chicken and fish samples were 0.11 kGy, 0.15 kGy, 0.14 kGy, 0.12 kGy, and 0.28 kGy, respectively. The mixed sprouts, chicken, and fish samples were inoculated with 5 log cfu/g of K. pneumoniae MTCC 109. The inoculated packs were irradiated at 4 °C with doses of 1, 1.5 and 2 kGy. Radiation treatment with 1.5 kGy dose resulted in complete elimination of 105 cfu/g of Klebsiella pneumoniae MTCC 109. Even after enrichment and selective plating no recovery of K. pneumoniae MTCC 109 was observed in the 1.5 kGy treated samples stored at 4 °C up to 12 days. The study shows that a 1.5 kGy dose of irradiation treatment is enough to eliminate 5 log cfu/g K. pneumoniae MTCC 109 from mixed sprouts. (author)