Diagnostic performance of microscopic stool examination in Campylobacter infection performed by different medical specialties

Background: Microscopic examination of stool samples can contribute to the early diagnosis of Campylobacter gastroenteritis. However, it is unclear whether the diagnostic performance is reliable when performed by physicians. Methods: This prospective study included fresh stool samples collected from patients with gastroenteritis between August 2018 and March 2020. The samples were used for microscopic examination through Gram staining. Two physicians, a clinical laboratory technician, and microbiologists performed the examinations. In addition, antigen tests (QuickNavi-Campylobacter; Denka Co., Ltd.) were evaluated for the samples collected between May 2019 and March 2020. Infection with Campylobacter spp. was confirmed when stool cultures or polymerase chain reaction tests provided positive results. Results: Microscopic examination was performed on 205 samples, of which 46 (22.4%) were positive for Campylobacter spp. For the microscopic examination, the sensitivity and specificity were 53.5% and 98.1% for physician A, 46.7% and 96.2% for physician B, 63.0% and 100% for the clinical laboratory technician, and 67.4% and 100% for microbiologists, respectively. The antigen testing was evaluated in 131 of the 205 samples and showed a sensitivity of 93.3% and specificity of 99.0%. Conclusions: Microscopic examination of the stool samples showed high specificity. The sensitivity when the examinations were performed by the physicians was insufficient. The rapid antigen tests can reliably detect Campylobacter spp. in stool samples.