Effect of antibiotics for infectious diarrhea on the duration of hospitalization: A retrospective cohort study at a single center in Japan from 2012 to 2015

[[[ Objective: ]]] Routine empirical antimicrobial therapy for patients with infectious diarrhea is not recommended in general practice. Conversely, prescription of empirical antibiotics for hospitalized patients remains controversial due to a lack of studies providing evidence for its benefits. Thus, this study aimed to examine whether empirical antimicrobial therapy would shorten the hospitalization duration for infectious diarrhea patients. [[[ Methods: ]]] This single-center, retrospective cohort study was performed at the Department of General Medicine and Emergency Care, Toho University Medical Center Omori Hospital, using medical records. Adult patients (aged ≥16 years) hospitalized for infectious diarrhea from 2012 to 2015 were enrolled. The primary outcome was the duration of hospitalization. Risk factors examined in parallel to antibiotic therapy included age, sex, relevant medical history, probiotics use, vital signs, leukocyte count, liver and renal functions, and microbiological data. [[[ Results: ]]] We enrolled 138 and 50 patients treated with and without antimicrobial therapy, respectively. The median hospitalization periods were 6.0 days (interquartile range, 4.0-7.0 days) and 5.0 days (interquartile range, 3.25-6.0 days) for patients treated with and without antibiotics, respectively (p = 0.007). Multiple regression showed that empiric antimicrobial therapy (p = 0.017), advanced age (p = 0.003), hematochezia (p = 0.008), elevated serum creatinine (p < 0.001), and elevated serum C-reactive protein (p = 0.002) were significant risk factors of longer hospitalization duration. [[[ Conclusion: ]]] Empirical antimicrobial therapy was found to relate to a longer hospitalization duration for infectious diarrhea patients. Although its effects on the patients’ symptoms were not evaluated, our results suggest that empirical antimicrobial therapy should be administered cautiously to not only outpatients, but also hospitalized patients.