Reduced Vancomycin Susceptibility in Clostridioides difficile Is Associated With Specific Ribotypes.

Area of Science:

• Infectious Diseases
• Microbiology
• Clinical Medicine

Background:

• Reduced vancomycin (VAN) susceptibility in *Clostridioides difficile* isolates is linked to poorer patient outcomes.
• Factors driving infections with these less susceptible strains remain largely unknown.
• Understanding these factors is critical for effective infection control and treatment.

Purpose of the Study:

• To identify specific risk factors associated with reduced vancomycin susceptibility in clinical *C. difficile* isolates.
• To analyze host, pathogen, and hospital characteristics that predict infection with reduced VAN susceptibility.
• To inform clinical practices and surveillance strategies for *C. difficile* infections.

Main Methods:

• A multicenter cohort study involving hospitalized adult patients with *C. difficile* infection (CDI) from 2016 to 2021.
• Agar dilution VAN susceptibility testing and ribotyping were performed on clinical isolates.
• Medical chart review and multivariable analysis were used to identify predictors of reduced VAN susceptibility.

Main Results:

• Of 594 isolates, 29% exhibited reduced VAN susceptibility (MIC > 2 µg/mL).
• Ribotype 027 (RT 027) and RT 255 were significantly associated with reduced VAN susceptibility (OR 13.4 and 2.9, respectively).
• Ribotype 014-020 (RT 014-020) isolates were more likely to be susceptible to VAN (OR 0.41), and the prevalence of reduced susceptibility strains increased over time.

Conclusions:

• Specific *C. difficile* ribotypes, notably RT 027, are the sole independent predictors of reduced vancomycin susceptibility.
• No patient or hospitalization characteristics independently predicted infection with reduced susceptibility strains.
• Enhanced clinical surveillance of RT 027 and other reduced susceptibility strains is recommended to guide antibiotic prescribing.