Yersinia enterocolitica biotype 1A: a possible new trigger of reactive arthritis.

Yersinia enterocolitica (YE) biotype 1A is generally considered non-pathogenic, and the role of it in causing reactive musculoskeletal complications is unclear. We evaluated the capability of YE biotype 1A to induce reactive arthritis (ReA) and other reactive musculoskeletal symptoms. Analysis of self-reported musculoskeletal symptoms was supplemented with a telephone interview (with a permission to acquire copies of patient files from a local physician or hospital) and/or clinical examination of subjects with recent musculoskeletal symptoms after a positive stool culture for YE. The diagnoses of ReA and reactive tendinitis and enthesitis (ReTe) were defined as "definite" when based on clinical examination and/or on interview by phone and "probable" when based solely on the questionnaire. Of 120 subjects, who reported musculoskeletal symptoms, 100 were included in the final analysis. Among these 100 patients, 68% had YE biotype 1A, 16% YE bio/serotype 4, and 1% biotype 2 infection; the remaining 15% had different YE-like strains or a non-biotypable strain. Of the 21 patients with ReA and of the 14 patients with ReTe, the diagnosis was definite in 9 and 7 patients and probable in 12 and 7 patients, respectively. The clinical picture of ReA caused by YE biotype 1A was similar with other bio/serotypes of YE. The definite ReA due to YE biotype 1A occurred in middle-aged adults (5 men, 4 women) with the most frequently affected joints being the knees and ankles. We suggest that YE biotype 1A should be taken into account as a new trigger of ReA.