الكشف عن وجود يرسينيا القولون في بعض المنتجات الغذائية في محافظة كربلاء وتقييم تأثير الطرق الحرارية والاشعة فوق البنفسجية على حيويتها

Detection of Yersinia enterocolitica in Selected Food Product in Karbala Province and Assessment of Thermal and U.V Light Methods on its Viability

Summary
The recently study have been conducted to detection the prevalence of Yersinia enterocolitica in raw milk, calve meat, chicken meat and egg in markets of Kerbala province. 200 samples 50 from each one have been collected aseptically and send to laboratory for isolation and identification of Yersinia enterocolitica , the study beginning from November 2024 to April 2025, the results of prevalence of Yersinia enterocolitica have been showed 34% in raw milk ,2% egg,14%calf meat and 20%chicken meat respectively. The results of culturing of samples on CIN medium were revealed the presence of characteristic colony of Yersinia enterocolitica, the staining of Yersinia enterocolitica by gram stain have been appeared gram negative coccoid arranged in pairs or chains with varying length. the results of biochemical test for Yersinia enterocolitica were showed catalase, hydroxide potassium positive while oxidase, lactose fermentation negative.
A 24-hour culture of Yersinia enterocolitica was standardized to a 0.5 McFarland turbidity. Calf and chicken meat samples were aseptically diced and immersed in the bacterial suspension, while whole eggshells were surface-inoculated via dipping to achieve contamination. The inoculated samples were subsequently divided into experimental groups for antimicrobial intervention. Thermal treatment was applied using a thermal temperature, with samples exposed to 60°C for 30 minutes and 70°C for 15 minutes. Separate groups were subjected to UV-C irradiation at a wavelength of 254 nm for exposure times of 10, 15, and 20 minutes. Following their respective treatments, all samples were homogenized in a neutralizing buffer, serially diluted, and plated onto Cefsulodin-Irgasan-Novobiocin (CIN) agar. Plates were incubated at 34°C for 48 hours. Bacterial viability was assessed through the enumeration of characteristic bull’s-eye colonies, with results recorded as the presence or absence of growth
The results of Ab resistant showed that the highest resistance rates were observed against Amoxicillin and Penicillin G. Considerable resistance was demonstrated against Spiramycin, Lincomycin, and Nitrofurantoin. A moderate level of resistance was noted for Ciprofloxacin, Cephalexin, Gentamicin, Streptomycin, Tobramycin, and Erythromycin. The results showed that 34 samples were confirmed as positive by PCR analysis, representing a 17% detection rate. This identification was based on the amplification of 16S rRNA gene, which was utilized for broad bacterial identification. On the other hand, the results showed that bacterial viability was observed across all food matrices subsequent to a 10-minute UV-C exposure, with substantial colony formation indicating a negligible reduction in bacterial load.
A partial reduction in microbial population was achieved following an extended exposure of 15 minutes, as evidenced by a marked decrease in colony counts; however, complete eradication was not obtained. Total inactivation was conclusively demonstrated only after a 20-minute UV-C treatment, with an absence of characteristic colony formation on all cultured media. Regarding thermal interventions, survival of Yersinia enterocolitica was confirmed following treatment at 60°C for 30 minutes, with viable colonies successfully recovered from all inoculated samples. Conversely, total microbial inactivation was observed after exposure to a temperature of 70°C for a duration of 15 minutes, as indicated by a complete absence of growth on all plating media.