Antimicrobial Susceptibility Patterns and Genetic Diversity of spp. Isolates from Patients with Diarrhea in South Korea.

This study aimed to characterize the latest antimicrobial resistance patterns and genetic diversity of spp. isolated from patients with acute diarrhea in Korea. In total, 371 clinical isolates (361 and 10 ) were collected from patients with diarrhea in 106 medical institutions of six provinces during the seasonal peak (April-September 2022) in South Korea. We then assessed their antimicrobial susceptibility to eight antimicrobial agents and performed multilocus sequence typing (MLST). This study investigated the antimicrobial resistance (AMR) profiles to tetracycline (32.3%), nalidixic acid (64.9%), and ciprofloxacin (83.3%), confirming high levels of the latter even after its Korean ban in 2010. However, tetracycline resistance displayed a decreasing trend. Alternatively, significantly lower resistance rates to clindamycin (0.8%), azithromycin (0.53%), erythromycin (0.53%), and gentamicin (0.53%) as well as absolute susceptibility to florfenicol (0%) were observed. Four and three isolates (7/371, 1.88%) were classified as multidrug-resistant (MDR) to at least three antimicrobial classes. MLST identified a high genetic diversity with 21 clonal complexes (CCs) and sixty-six sequence types (STs), including eight novel STs. The high CC frequency of comprised CC21 (37.7%), CC22 (13.8%), and CC206 (9.4%), while was predominated by CC828 (90%). The high CC21 and CC828 strain prevalence in this study was consistent with their worldwide distribution. This study highlights that quinolone- and tetracycline-resistant circulate in Korea with diverse genotypes, providing important information that could contribute to controlling and preventing increasing antimicrobial resistance in patients.