LAUSR

Abstract Background Recurrent Clostridium difficile infection (R-CDI) remains a significant healthcare problem. Our aim was to analyze sporulation and antimicrobial resistance of C. difficile in biofilms as a potential reservoir for recurrence. Methods C. difficile isolates obtained from patients with initial CDI (I-CDI) (n = 93) and from patients with R-CDI (n = 39) were analyzed. Isolates were identified by PCR and MALDI-TOF MS and ribotyped using 16S RNA amplification and capillary electrophoresis. Biofilm production was assessed by the crystal violet microtiter-plate method. Susceptibilities to vancomycin and linezolid were determined both in planktonic and in biofilm cells and total viable cells and spore were quantified in biofilm cells. Results All I-CDI and R-CDI isolates were biofilm producers and >75% were ribotype 027. MICs for vancomycin and linezolid were higher in biofilm than in planktonic cells in both I-CDI and R-CDI isolates (P < 0.05) (Table 1). Isolates recovered from R-CDI showed a higher vancomycin resistance (MIC >2 mg/L) and sporulated 2 log10 higher than isolates from I-CDI (P < 0.01 and P = 0.086, respectively). Table 1. Antimicriobial Susceptibilities of C. difficile From I-CDI and R-CDI Patients. Vancomycin Linezolid Group Phase Range(mg/L) GM(mg/L) % R Range(mg/L) GM(mg/L) % R I-CDI Planktonic 0.25-4 1.68* 9.2 (6/69)* 0.03-32 3.38* 34.8 (24/69) Biofilm 8 >128 73.9* 100 (73/73) 4 >128 60.85* 98.5 (66/67) R-CDI Planktonic 2-4 1.69* 27.3 (9/33)* 0.25-128 3.31* 35.1 (14/37) Biofilm 4 >128 72.6* 100 (34/34) 8 >128 59.5* 93.5 (29/31) *Significant difference P < 0.05; GM: Geometric mean; %R: Resistant. Conclusion C. difficile isolates in biofilms were 100-fold more resistant to vancomycin than planktonic cells. Isolates recovered from patients with R-CDI showed higher sporulation capacities than C. difficile recovered from I-CDI patients. Our data suggest that biofilm formation ability may play a key role in R-CDI by contributing to vancomycin resistance/tolerance. Furthermore, C. difficile from recurrent episodes sporulated to a greater capacity which may facilitate prolonged C. difficile persistence in the gut following therapy for R-CDI. Disclosures All authors: No reported disclosures.