Investigation of the role of Yersinia enterocolitica and Yersinia pseudotuberculosis in the etiology of patients diagnosed with mesenteric lymphadenitis

Mesenteric lymphadenitis (ML) is a common condition among children evaluated with suspected acute abdomen and constitutes an important differential diagnostic problem in pediatric emergency departments, particularly due to its potential to be confused with acute appendicitis. The lack of specific clinical and laboratory findings complicates the diagnosis, and ultrasonography is used as the primary imaging modality for diagnosis. Nevertheless, the etiology and natural course of the disease have not yet been fully elucidated. Among the bacterial pathogens prominent in the etiology, Yersinia enterocolitica and Yersinia pseudotuberculosis are zoonotic and are transmitted through contaminated food or water. Data from Türkiye regarding the frequency of these pathogens in pediatric ML cases are quite limited. In this study, it was aimed to investigate the presence of Yersinia enterocolitica and Yersinia pseudotuberculosis in the etiology of mesenteric lymphadenitis in pediatric patients using serological (ELISA, Western Blot) and molecular (PCR) methods. Between January 2024 and December 2024, 60 pediatric patients diagnosed with ML at the Department of Pediatrics, Pamukkale University Faculty of Medicine, were included in the study. The clinical and laboratory characteristics of the patients were recorded; ELISA and Western Blot were performed on serum samples, and the presence of Yersinia was investigated in stool samples using real-time PCR, and positive and negative cases were compared. According to the results obtained, ELISA positivity was detected in 8 cases (13.3%), and borderline values were found in 2 cases (3.3%); Western Blot positivity was confirmed in 7 of these 10 samples (11.7%). Among the positive cases, 5 were classified as Y. enterocolitica, and 2 as Yersinia spp. for which species-level differentiation could not be determined. All 41 stool samples examined by PCR were found to be negative. No significant differences were detected between Yersinia-positive and Yersinia-negative cases in terms of clinical and laboratory findings; only eosinophil levels were found to be statistically significantly higher in the positive group (p = 0.034); however, eosinophil levels remained within normal limits in both groups. In conclusion, Yersinia positivity was detected in 11.7% of pediatric patients diagnosed with ML, with Y. enterocolitica constituting the majority of these cases. These findings indicate that Yersinia spp. infections may be a more important etiological factor in pediatric mesenteric lymphadenitis cases in Türkiye than previously assumed. This study contributes to the epidemiological data on the etiology of mesenteric lymphadenitis and demonstrates the need for larger, multicenter studies.