Reviewed by: S. Shaefer Spires, MD, Duke Center for Antimicrobial Stewardship and Infection Prevention, Durham, NC
The authors examined 438 clinical C. difficile isolates from a large hospital in Houston and 98 from a hospital in Nairobi, Kenya for vancomycin non-susceptibility. They found an alarming number, 114 of 438 (26%) isolates in Houston and 66 of 98 (67%) in Nairobi to be vancomycin non-susceptible (≥4ug/mL). To assess the ability of these isolates to cause infection, they infected mice with an isolate with an MIC > 16 ug/mL, then treated with oral vancomycin (20mg/kg). Only 30% of these mice survived 5 days post-infection and all them died by day 10. The high proportion of the non-susceptible isolates in these centers was striking, but how much does this matter in clinical practice? We do not yet know. Previous studies have shown the proportion of non-susceptible isolates to be 1% or less. This study identifies vancomycin resistance as an emerging, potential cause of treatment failure in C. difficile infection, and hopefully more clinical studies will follow to help unearth the clinical relevance of higher MICs to vancomycin.
Reference:
Darkoh C, Keita K, Odo C, Oyaro M, Brown E, Arias CA, Hanson BM, DuPont HL. Emergence of Clinical Clostridioides difficile Isolates with Decreased Susceptibility to Vancomycin. Clin Infect Dis. 2022;74(1):120-126. DOI: 10.1093/cid/ciaa912