Clostridium difficile. Susceptibility profiles to Vancomycin and Metronidazol in a pediatric population.

Abstract

Background: There has been an increase in incidence and morbi-mortality of Clostridium difficile infection (CDI) in the last few years and even though it was considered a low risk disease in pediatric population it has become an emerging problem. The objective of this study was to evaluate the susceptibility of C. difficile isolates to the antimicrobial drugs of choice from patients with CDI in an Argentinean Pediatric Hospital Methods & Materials: Retrospective study. From January 1, 2014, through September 30, 2017, 5686 stool samples (SS) were analyzed to detect C. difficile toxins A and B (tAB). Those that tested positive were cultured in order to isolate C. difficile to conduct in-vitro susceptibility testing. Minimal Inhibitory Concentration (MIC) values were determined for Metronidazol (MTZ) and Vancomycin (VAN) using the epsilometer test method (E-test). The breakpoints established by the Clinical and Laboratory Standards Institute (CLSI M100-S27 Document) and the European Committee of Antimicrobial Susceptibility Testing (EUCAST - Version 7.0) were used to analyze the results. Results: Among all 5686 SS only 119 (2%) tested positive for tAB and 89 C. difficile were isolated. The MIC50 and MIC90 of MTZ were 0.032 and 0.064 μg/ml, respectively. The MIC50 and MIC90 of VAN were 0.5 and 1 μg/ml, respectively. Conclusion: According to CLSI breakpoints all the Hospital isolates of C. difficile were susceptible to MTZ. As there are no CLSI breakpoints for VAN we considered EUCAST breakpoints which are based on epidemiological cut-off values. This allowed us to distinguish wild types isolates (MIC ≤ 2 μg/ml) from those with reduced susceptibility (>2 μg/ml). All isolates behaved as wild types. We found no discrepancies between our experience in this study and previous reports regarding C. difficile susceptibility to the these antimicrobial agents.