Situational analysis on fluoroquinolones use and characterization of high-level ciprofloxacin-resistant by integrated broiler operations in South Korea.

Fluoroquinolones are classified as "critically important antimicrobials for human medicine"; however, their extensive use in livestock poses a significant health risk to humans as it leads to the rapid spread of antimicrobial resistance. This study confirmed that 40.0%-71.4% of the farms in three of the five integrated broiler operations were administered ciprofloxacin (CIP). Moreover, preventive purposes (60.9%), veterinarian prescriptions (82.6%), drinking water route (100%), and 1 to 3 days (82.6%) of age were significantly highest ( < 0.05). 194 high-level ciprofloxacin-resistant (HLCR) () were found in 65 of 74 farms, and of which, the prevalence of (63.9%), (60.3%), (64.9%), (38.7%), and (34.0%) was significantly highest ( < 0.05). 154 (79.4%) isolates showed MDR, and the distribution of MDR was significantly differences among the operations ( < 0.05). All HLCR possessed double mutations in and , and S83I/S80I (90.7%) mutations were most commonly identified. Interestingly, the distribution of isolates with MICs ≥ 512 for both CIP and moxifloxacin was significantly higher in CIP-administered farms (56.5%) than in non-CIP-administered farms (41.4%) ( < 0.05). Also, the prevalence of strong or moderate biofilm formers in HLCR was significantly higher than that of weak and no biofilm formers ( < 0.05). HLCR were heavily distributed in the broiler farms in Korea; therefore, it is necessary to minimize the prevalence of resistant bacteria structural management regulations such as cleaning and disinfection of farm environments.