In vitro activity of cefiderocol against clinically relevant Gram-negative bacilli collected in China in 2023.

OBJECTIVE

Cefiderocol is a siderophore-conjugated cephalosporin with potent in vitro activity against aerobic Gram-negative bacteria, including Enterobacterales and glucose-nonfermenting species. This study aimed to explore the in vitro activity of cefiderocol against 2049 clinical isolates collected from 63 hospitals across China in 2023.

METHODS

Antimicrobial susceptibility testing was performed using broth microdilution following Clinical and Laboratory Standards Institute (CLSI) 2024 guidelines for Enterobacterales (n = 993), Pseudomonas aeruginosa (n = 377), Acinetobacter baumannii (n = 368), Stenotrophomonas maltophilia (n = 188) and Burkholderia cepacia (n = 123). Results were interpreted by CLSI breakpoints.

RESULTS

Cefiderocol had potent in vitro activity against Enterobacterales (susceptibility rates: 93.5%-100%, minimum inhibitory concentrations inhibiting 90% of isolates [MIC90]: 0.25-4 µg/mL). For meropenem-resistant Escherichia coli and Klebsiella pneumoniae, the MIC90 values were 8 µg/mL and 4 µg/mL, and susceptibility rates were 86.4% and 91.0%, respectively. For 11 meropenem-resistant Enterobacter cloacae, susceptibility rate was 36.4% (MIC90: 16 µg/mL). Susceptibility rates for P. aeruginosa, A. baumannii and S. maltophilia were 99.7%, 99.5% and 98.4% overall, and 98.6% and 99.1% for meropenem-resistant P. aeruginosa and A. baumannii, respectively. The MIC90 value for B. cepacia was 0.25 µg/mL and 100% of isolates had cefiderocol MIC values ≤2 µg/mL. Cefiderocol had similar in vitro activity to colistin and tigecycline, and it was more active than ceftazidime-avibactam and imipenem-relebactam against meropenem-resistant E. coli, K. pneumoniae and P. aeruginosa.

CONCLUSIONS

Cefiderocol showed potent in vitro activity against most Gram-negative species collected in China; however, continuous surveillance of resistance patterns, particularly for E. cloacae, is essential to ensure its long-term effectiveness.