OBJECTIVE Timely antibiotic therapy in selected cases of diarrhea associated with bacterial infections can reduce the duration and severity of illness and prevent complications. The availability of a predictive index before identification of causative bacteria would aid in the choice of a therapeutic agent. METHODS The study included patients admitted to the pediatrics unit at Konyang University Hospital for acute inflammatory diarrhea from August 1, 2015 to July 31, 2016 who underwent multiplex polymerase chain reaction testing. Of 248 patients, 83 had positive results. The clinical symptoms and blood test results were examined in 61 patients with Campylobacter spp. (25 patients), Salmonella spp. (18 patients), and Clostridium perfringens (18 patients) infections. The mean age of the 61 patients (male:femal=31:30) was 84.0±54.8 months, and the mean hospital stay was 4.6±1.7 days. RESULTS There were no statistical differences in sex, age, clinical symptoms, or signs. Patients with Campylobacter infection were significantly older (P=0.00). C-reactive protein (CRP) levels in patients with Campylobacter infection were higher than those in the other 2 groups, at 9.6±6.1 mg/dL. The results of receiver-operating characteristic curve analysis showed that the cutoff age was ≥103.5 months (sensitivity, 72%; specificity, 86%) and the CRP cutoff level was ≥4.55 mg/dL (sensitivity, 80%; specificity, 69%). CONCLUSIONS Age (≥103.5 months) and higher CRP level (≥4.55 mg/dL) were good predictors of Campylobacter enterocolitis. If neither criterion was met, Campylobacter enterocolitis was unlikely (negative predictive value 97.2%). When both criteria were met, Campylobacter enterocolitis was highly likely.