Analysis of Clinical Characteristics and Antimicrobial Resistance in 249 Isolates of Streptococcus mitis: a Single-Centre Study.

Cases of invasive infection caused by Streptococcus mitis have been gradually increasing, but less attention has been paid to its clinical characteristics and drug resistance. This study conducted a single-center retrospective analysis of patients with S. mitis-positive results admitted to a tertiary hospital in Yancheng between January 2020 and December 2024. Data were extracted from case notes and electronic medical records. There were 249 cases of S. mitis detected, with community-acquired infections (44.98%), colonization (46.59%) and hospital-acquired infections (8.43%). Of these, the three departments with the highest detection rates were pediatrics (22.09%), urology (19.68%), and stomatology (11.65%). Primary specimen sources included secretions (23.30%), bronchoalveolar lavage fluid (23.30%), urine (20.48%), and blood (17.67%). In terms of years, the detection rate of S. mitis infection showed an annual increase, while antimicrobial resistance remained stable with a decrease in the year 2024. Our analysis identified associations between patient ages and infection type, specimen source, and antimicrobial resistance profile. Furthermore, we observed distinct resistance patterns across different infection types. These findings underscore the need for enhanced hospital surveillance measures to monitor antimicrobial resistance trends and nosocomial infection patterns associated with S. mitis.