Seasonal variation in the prevalence of Gram-negative bacilli in sputum and urine specimens from outpatients and inpatients.

Objectives: ) in sputum and urine specimens from outpatients and inpatients differed by season and according to temperature and humidity changes. Methods: In this retrospective study, microbiologic data for adult patients from 2008 to 2019 were retrieved from the electronic database of a hospital in Japan. Data were categorized by specimen type (sputum and urine) and specimen collection (outpatient and inpatient). Associations between variables were assessed using Spearman's rank correlation coefficients. Differences between groups were assessed using Pearson's chi-square test and analysis of discrete variance. Results: (r=0.2602, p=0.0016) from sputum. Conclusions: GNB were isolated more frequently in summer and autumn than in other seasons. These seasonal trends were observed for both outpatient and inpatient specimens. Seasonality should be considered for optimal infection control of GNB in hospitals.