Clustered regularly interspaced short palindromic repeat associated protein genes cas1 and cas2 in Shigella / 中华流行病学杂志

ABSTRACT

Objective To detect the distribution of clustered regularly interspaced short palindromic repeat(CRISPR)associated protein genes cas1 and cas2 in Shigella and to understand the characteristics of CRISPR with relationship between CRISPR and related characteristics on drug resistance. Methods CRISPR associated protein genes cas1 and cas2 in Shigella were detected by PCR,with its products sequenced and compared.Results The CRISPR-associated protein genes cas1 and cas2 were found in all the 196 Shigella isolates which were isolated at different times and locations in China. Consistencies showed through related sequencing appepared as followscas2,cas1 (a) and cas1(b)were 96.44%,97.61%and 96.97%,respectively. There were two mutations including 3177129 site(C→G)and 3177126 site(G→C)of cas1(b)gene in 2003135 strain which were not found in the corresponding sites of Z23 and 2008113. Results showed that in terms of both susceptibility and antibiotic-resistance,strain 2003135 was stronger than Z23 and 2008113. Conclusion CRISPR system widely existed in Shigella,with the level of drug resistance in cas1(b) gene mutant strains higher than in wild strains. Cas1(b)gene mutation might be one of the reasons causing the different levels of resistance.