In Vitro Activity of Cefiderocol Against Multi-Drug-Resistant Gram-Negative Clinical Isolates in Romania

Area of Science:

• Microbiology
• Infectious Diseases
• Pharmacology

Background:

• Acquired carbapenem resistance in Gram-negative bacteria poses a significant threat in serious infections.
• Multidrug-resistant (MDR) Gram-negative pathogens require novel therapeutic agents.

Purpose of the Study:

• To evaluate the in vitro activity of cefiderocol against MDR Gram-negative clinical isolates from Romania.
• To assess cefiderocol susceptibility in various Gram-negative species, including Enterobacterales and non-fermenters.

Main Methods:

• Retrospective study of 89 consecutive MDR Gram-negative isolates (November 2024-February 2025).
• Includes Enterobacterales (n=66) and non-fermenters (n=23) like P. aeruginosa, S. maltophilia, and A. baumannii.
• Disk diffusion method used for susceptibility testing.

Main Results:

• Overall cefiderocol susceptibility was 52.8% for Enterobacterales and P. aeruginosa, and 63.6% for Enterobacterales alone.
• 66.3% of all isolates were susceptible by disk diffusion.
• NDM-only producing K. pneumoniae were resistant, while NDM/OXA-48 co-producers showed 65.3% susceptibility. All P. aeruginosa were susceptible. A. baumannii susceptibility was 68.8%.

Conclusions:

• Cefiderocol demonstrates potential for treating MDR Gram-negative infections.
• Emergence of NDM-producing isolates resistant to cefiderocol necessitates vigilant microbiological monitoring.
• Strict surveillance is essential to prevent the rapid spread of cefiderocol resistance.