The extended-spectrum β-lactamase (ESBL) CTX-M-55, a CTX-M-15 variant distinguished by an amino-acid substitution (Ala77Val), has enhanced enzymatic activity due to higher structural stability. In Korea, CTX-M-55 remains insufficiently characterized, particularly in the context of urinary tract infections (UTIs). We identified CTX-M-55 among uropathogenic Escherichia coli isolates and compared its microbiological characteristics with those of CTX-M-15. In total, 247 E. coli isolates were collected from patients with acute pyelonephritis at Hanyang University Seoul Hospital, an 860-bed tertiary-care hospital, between July 2019 and December 2021. ESBL production was confirmed using a double-disk synergy test, and minimum inhibitory concentrations (MICs) were determined. Resistance genes were detected using PCR, and CTX-M-15 sequences were analyzed. Among 38 isolates detected using PCR, eight were confirmed as CTX-M-55 using further sequence analysis. CTXM-55 showed (P > 0.05) a trend toward increased resistance to aztreonam, cefotaxime, ceftazidime, and cefepime, while showing decreased resistance to amoxicillin/clavulanate and piperacillin/tazobactam. CTX-M-55 had higher MIC 50 values than CTX-M-15 for ceftazidime ( > 16 vs. 8 µg/mL), cefepime (32 vs. 1 µg/mL), and piperacillin/tazobactam (0.5 vs.0.25 µg/mL). Virulence factors and coexisting resistance genes did not significantly differ.Our findings suggest that, given its increased resistance to ceftazidime and cefepime, CTXM-55 should be considered when treating UTIs in Korea.

This study employed focus group interviews (FGIs) to evaluate the preparedness and training requirements for an emerging infectious disease response system in the Republic of Korea.Based on the FGIs, the critical role of interdepartmental cooperation in responding to emerging infectious diseases was identified, with agencies such as public health centers, police, and fire services playing key roles in scene control, decontamination, and patient transport. Frequent staff turnover and a lack of trained personnel at local government levels were significant challenges, necessitating the development of training materials for unskilled workers. Civil complaints, common during outbreaks, require public officials to be educated on legal frameworks and the management of patients’ rights. The absence of standardized procedures for managing patients, such as bed assignments considering underlying conditions and sample collection, underscores the need for comprehensive guidelines.Interviewees emphasized cross-departmental training, detailed manuals, and legal education to improve infectious disease response capabilities.

This study employed focus group interviews (FGIs) to evaluate the preparedness and training requirements for an emerging infectious disease response system in the Republic of Korea.Based on the FGIs, the critical role of interdepartmental cooperation in responding to emerging infectious diseases was identified, with agencies such as public health centers, police, and fire services playing key roles in scene control, decontamination, and patient transport. Frequent staff turnover and a lack of trained personnel at local government levels were significant challenges, necessitating the development of training materials for unskilled workers. Civil complaints, common during outbreaks, require public officials to be educated on legal frameworks and the management of patients’ rights. The absence of standardized procedures for managing patients, such as bed assignments considering underlying conditions and sample collection, underscores the need for comprehensive guidelines.Interviewees emphasized cross-departmental training, detailed manuals, and legal education to improve infectious disease response capabilities.

This study employed focus group interviews (FGIs) to evaluate the preparedness and training requirements for an emerging infectious disease response system in the Republic of Korea.Based on the FGIs, the critical role of interdepartmental cooperation in responding to emerging infectious diseases was identified, with agencies such as public health centers, police, and fire services playing key roles in scene control, decontamination, and patient transport. Frequent staff turnover and a lack of trained personnel at local government levels were significant challenges, necessitating the development of training materials for unskilled workers. Civil complaints, common during outbreaks, require public officials to be educated on legal frameworks and the management of patients’ rights. The absence of standardized procedures for managing patients, such as bed assignments considering underlying conditions and sample collection, underscores the need for comprehensive guidelines.Interviewees emphasized cross-departmental training, detailed manuals, and legal education to improve infectious disease response capabilities.

This study employed focus group interviews (FGIs) to evaluate the preparedness and training requirements for an emerging infectious disease response system in the Republic of Korea.Based on the FGIs, the critical role of interdepartmental cooperation in responding to emerging infectious diseases was identified, with agencies such as public health centers, police, and fire services playing key roles in scene control, decontamination, and patient transport. Frequent staff turnover and a lack of trained personnel at local government levels were significant challenges, necessitating the development of training materials for unskilled workers. Civil complaints, common during outbreaks, require public officials to be educated on legal frameworks and the management of patients’ rights. The absence of standardized procedures for managing patients, such as bed assignments considering underlying conditions and sample collection, underscores the need for comprehensive guidelines.Interviewees emphasized cross-departmental training, detailed manuals, and legal education to improve infectious disease response capabilities.