Toxin A and B Genes Expression of Clostridium Difficile in the Subminimum Inhibitory Concentration of Clindamycin, Vancomycin and in Combination With Ceftazidime

Background and objectives: antibiotics prescribed for infections have diverse effects on microbiota and the pathogenclostridium difficile (c. difficile) as the most important antibiotic-associated diarrhea. this study aims to determine the geneexpression of toxins a and b at the transcription level in the sub-mic of vancomycin (van), clindamycin (cli), and ceftazidime(caz) alone and in combination.materials and methods: the mic and fractional inhibitory concentration (fic) of two c. difficile samples (a clinical isolateand atcc 9689) were determined by microdilution and checkerboard microdilution methods, respectively. the total rnawas extracted from the medium inoculated with ~106 cfu/ml of fresh bacteria in the pre-reduced medium containing ½mic of antibiotics alone and ½ fic of antibiotics in combination. real-time pcr was performed by sybrgreen methods intriplicate, and the data were analyzed by the comparative δδct method.results: all antibiotics except caz (alone and in combination) decreased the gene expression of toxins a and b within 24hours. van and cli reduced toxin gene expression within 24 and 48 hours. however, caz alone and in combination withvan as well as cli increased the gene expression of toxins a and b.conclusion: the results confirmed toxin gene transcription and toxin production are associated with the type of isolates andantibiotics, as well as the combined form of antibiotics. this could be the reason which can explain the occurrence of c.difficile infection among patients who were treated with the third generation of cephalosporins alone and in combination withanother antibiotic in the form of combinational therapy.