АПРОБАЦИЯ АЛГОРИТМА ВЫДЕЛЕНИЯ YERSINIA ENTEROCOLITICA ИЗ ФЕКАЛИЙ ТЕЛЯТ С ПРЕДВАРИТЕЛЬНЫМ ПЦР-СКРИНИНГОМ В РЕАЛЬНОМ ВРЕМЕНИ

The culture-based detection of Yersinia enterocolitica in feces is complicated by low bacterial counts and competition from the associated microbiota. Systematic data on the circulation and characteristics of Y. enterocolitica isolates in farm animals remain limited in Kazakhstan and Central Asia. This study aimed to evaluate a sequential detection algorithm comprising cold enrichment, species-specific real time PCR targeting the foxA gene, selective cultivation, and MALDI-TOF MS identification of Y. enterocolitica from the feces of diarrheic calves. Twenty-five rectal samples from Simmental calves aged ≤1 month were analyzed. Following enrichment in buffered peptone water at 4°C for 10 days, real time PCR targeting the foxA gene was performed. PCR-positive enrichment cultures were plated onto CIN agar, and suspected colonies were identified using MALDI-TOF MS. Antimicrobial susceptibility testing of seven isolates was performed using the disk diffusion method. Proportions are presented with exact 95% confidence intervals (CIs). The foxA gene was detected in 9/25 samples (36.0%; 95% CI 18.0–57.5). Cultures identified as Y. enterocolitica were recovered from 7/25 samples (28.0%; 95% CI 12.1–49.4), corresponding to 7/9 PCR-positive samples (77.8%; 95% CI 40.0–97.2). In the initial interpretation, all isolates exhibited ampicillin-resistant phenotypes and positive cefoxitin screening results, whereas 5/7 isolates were resistant to amoxicillin/clavulanic acid. The sequential protocol enabled successful recovery of Y. enterocolitica isolates from the majority of foxA-positive enrichment cultures and may serve as a practical prototype for regional surveillance. However, the presented data do not demonstrate the diagnostic sensitivity, specificity, or optimality of the algorithm, as alternative protocols were not compared. Further characterization, including virulence gene profiling, bioserotyping, and whole-genome sequencing, is required to assess the zoonotic risk of the recovered isolates.