Gene analysis for the CTX-M-9 group extended spectrum beta-lactamases in clinical isolates of Shigella

Objective:To understand the genotype distribution of CTX-M-9 group extended spectrum beta-lactamases(ESBLs) in clinical isolates of Shigella in Xicheng District of Beijing,and to analyze the species,quantity and polymorphism of CTX-M-9 group gene.Methods: Ninety-four strains of non-reduplicative clinical isolates of Shigella were colleted from 2008 to 2011 in Xicheng District of Beijing,the CTX-M-9 group ESBLs gene was detected by polymerase chain reaction(PCR),then sequencing for PCR positive productions were performed,the sequencing results were compared in GenBank to determine gene subtypes,meanwhile the nucleotide sequence was analyzed by means of DNAman software to determine SNPs site.Results: Among 94 strains of Shigella,Seventeen strains(18.09%) carried CTX-M-9 group ESBLs gene,furthermore,which was detected in Shigella flexneri,Shigella sonnei and Shigella boydii.The results of DNA sequence analysis showed that CTX-M-9 group ESBLs were all CTX-M-14 subtype,and no SNPs site was found.Conclusion: The CTX-M-9 type ESBLs in Xicheng District of Beijing are mainly CTX-M-14 subtype,and the gene structure is stable,without gene mutation,which exist widely in different serum types of Shigella.