ABSTRACT
Objective To develop a multiplex polymerase chain reaction (PCR )method for detecting and genotyping moxifloxacin-resistant Clostridium difficile (C.difficile)isolates.Methods Specific PCR primers of slpA genotypes gr,hr,fr,gc08 and 078 were designed according to the differences of slpA nucleotide sequences in different C.difficile genotypes,and the house-keeping gene tpi specific PCR primers were also added for the construction of multiplex PCR method.Nine common intestinal normal and pathogenic strains were used to verify the specificity of slpA multiplex PCR for the detection of C.difficile.Forty-six C.difficile reference strains,belonging to 11 slpA genotypes,were used to verify the ability of the multiplex PCR method for dectecting and genotyping.Thirty-nine moxifloxacin-resistant clinical isolates were genotyped by the multiplex PCR,and its clinical value was evaluated by comparing with slpA sequence typing (slpA ST)method.Results All the 9 intestinal normal and pathogenic strains were negative when detected by the multiplex PCR.And tpi of 46 C. difficile reference strains were positive,and 36 strains belonging to slpA genotypes gr,hr,fr,gc08 and 078 were genotyped correctly.Other 10 strains which belonged to other 6 genotypes were non-typeable. Among 39 moxifloxacin-resistant clinical isolates,all were positive of tpi,and 32 isolates were typed correctly by the multiplex PCR method,including 22 slpA genotypes gc08,6 genotypes hr,2 genotypes fr,and 2 genotypes 078,which were consistent with slpA ST.However,7 isolates could not be typed by multiplex PCR,which were identified as other genotypes not included in the multiplex PCR by slpA ST. Conclusions A convenient and rapid multiplex PCR method for the detection of C.difficile is established successfully,which can distinguish among five slpA genotypes.slpA genotype gc08 is the common genotype of moxifloxacin-resistant clinical isolates.