The association between reduced vancomycin (VAN) susceptibility in clinical Clostridioides difficile isolates and poor clinical outcomes is well established. Although, specific factors contributing to infections with these strains remain unclear. This study identified certain ribotypes, notably RT 027, as significant independent risk factors for reduced VAN susceptibility.1
From 2016 to 2021, 594 hospitalized patients with C difficile infection (CDI) were analyzed. Among these patients, 173 (29%) showed reduced susceptibility to vancomycin, with a minimum inhibitory concentration (MIC) of 2 µg/mL for MIC50 and 4 µg/mL for MIC90. Demographics included 57% female, 55% over 65 years old, and 59% white/non-Hispanic; additionally, 53% experienced non-severe CDI episodes.1
Key Takeaways
- The study found that ribotype RT 027 is a significant independent risk factor for reduced vancomycin susceptibility in C difficile isolates, with a strong odds ratio of 13.4.
- Among 594 hospitalized patients with CDI, 29% demonstrated reduced susceptibility to vancomycin, indicating a concerning trend in treatment effectiveness.
- No specific patient or hospitalization factors were identified as reliable predictors of infections with vancomycin-resistant strains, highlighting the complexity of managing these infections.
Multivariable analysis indicated that ribotype (RT) 027 was significantly associated with reduced VAN susceptibility, with an odds ratio (OR) of 13.4 (95% confidence interval (CI): 7.7-23.4; p<.0001). Ribotype 255 also correlated positively (OR: 2.9; 95% CI: 1.4-6.1; p=.005), while ribotype 014-020 was more likely to be susceptible (OR: .41; 95% CI: .21-.80; p=.0092). Notably, no specific patient or hospitalization factors predicted infections with reduced susceptibility strains.1
Clinical isolates of C difficile were subjected to agar dilution testing for VAN susceptibility and ribotyping. Reduced susceptibility was defined as a MIC exceeding 2 µg/mL. A review of medical records focused on host, pathogen, and hospital characteristics to evaluate predictors of reduced VAN susceptibility.1
Previous coverage from Contagion indicated that reduced vancomycin susceptibility is linked to poorer treatment outcomes, including lower rates of sustained clinical response (SCR) and initial cure. Approximately 34% of isolates exhibited diminished susceptibility, with ribotype 027 being the most prevalent (77.4%).2
The study, conducted from 2016 to 2021, analyzed 300 adults diagnosed with CDI who received oral vancomycin. Patients with reduced susceptibility had a 76% SCR rate compared to 86% for susceptible strains (P = .031). Initial cure rates were also lower for these patients, with 89% achieving a cure versus 96% for those with susceptible strains (P = .04). Reduced susceptibility was an independent predictor of 30-day SCR (OR: .52; 95% CI: .28–.97; P = .04).2
Both studies highlight the crucial relationship between reduced vancomycin susceptibility in C difficile isolates and poor clinical outcomes. The first study identifies ribotype 027 as a significant risk factor, while the second confirms that diminished susceptibility is linked to lower rates of sustained clinical response and initial cure.
With the rising prevalence of these strains, particularly ribotype 027, there is an urgent need for improved clinical monitoring and susceptibility testing. Together, these findings underscore the importance of understanding C difficile epidemiology to guide effective treatment strategies and address antimicrobial resistance in this persistent public health challenge.
References
Eubank T, Dureja C, Gonzales-Luna A, et. al. Reduced vancomycin susceptibility in Clostridioides difficile is associated with specific ribotypes, Open Forum Infectious Diseases, 2024;, ofae588, https://doi.org/10.1093/ofid/ofae588
Eubank T, Dureja C, Garey K, et. al. Reduced Vancomycin Susceptibility in Clostridioides difficile Is Associated With Lower Rates of Initial Cure and Sustained Clinical Response. Clinical Infectious Diseases. Published February 21, 2024. Accessed October 30, 2024. Doi: https://doi.org/10.1093/cid/ciae087
