Toxin profiles and antimicrobial resistance patterns among toxigenic clinical isolates of Clostridioides (Clostridium) difficile

Document Type : Original Article


1 Department of Bacteriology and Virology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran

2 Professor Alborzi Clinical Microbiology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran

3 Shiraz HIV/AIDS Research Center, Institute of Health, Shiraz University of Medical Sciences, Shiraz, Iran

4 Bioinformatics and Computational Biology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran


Objective(s): Clostridioides (Clostridium) difficile infection as a healthcare-associated infection can cause life-threatening infectious diarrhea in hospitalized patients. The aim of this study was to investigate the toxin profiles and antimicrobial resistance patterns of C. difficile isolates obtained from hospitalized patients in Shiraz, Iran.
Materials and Methods: This study was performed on 45 toxigenic C. difficile isolates. Determination of toxin profiles was done using polymerase chain reaction method. Antimicrobial susceptibility to vancomycin, metronidazole, clindamycin, tetracycline, moxifloxacin, and chloramphenicol was determined by the agar dilution method. The genes encoding antibiotic resistance were detected by the standard procedures.
Results: The most frequent toxin profile was tcdA+, tcdB+, cdtAˉ, cdtBˉ (82.2%), and only one isolate harboured all toxin associated genes (tcdA+, tcdB+, cdtA+, cdtB+) (2.2%). The genes encoding CDT (binary toxin) were also found in six (13.3%) isolates. Resistance to tetracycline, clindamycin and moxifloxacin was observed in 66.7%, 60% and 42.2% of the isolates, respectively. None of the strains showed resistance to other antibiotics. The distribution of the ermB gene (the gene encoding resistance to clindamycin) was 57.8% and the tetM and tetW genes (the genes encoding resistance to tetracycline) were found in 62.2% and 13.3% of the isolates, respectively. The substitutions Thr82 to Ile in GyrA and Asp426 to Asn in GyrB were seen in moxifloxacin resistant isolates.
Conclusion: Our data contributes to the present understanding of virulence and resistance traits amongst the isolates. Infection control strategies should be implemented carefully in order to curb the dissemination of C. difficile strains in hospital.


Main Subjects

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