Detection of integron structure and sequence of drug resistance gene cassette in clinical multidrug resistant Shigella dysenteriae strains / 中华传染病杂志

ABSTRACT

Objective Clinical strains of Shigella dysenteriae isolated from eastern parts of India in 1988, 1995 and 2002 were examined for the presence of class 1, 2 and 3 integrons which closely related with drug resistance and the distribution of resistance gene cassette in order to clarify the influence of integron system on drug resistance of Shigella dysenteriae. Methods Susceptibility to antimicrobial agents was tested by the disk agar diffusion method. Class 1, 2 and 3 integron genes (intI) were screened by polymerase chain reaction (PCR) in 16 clinical strains with drug resistance.The variable regions of gene cassette of positive strains were sequenced. Results All 16 isolates were resistant to at least 4 agents including β-lactams, aminoglycosides, tetracyclines, sulfonamides,chloramphenicols and quinolones. Class 1 integron gene was detected in 13 strains and all isolates carried class 2 integron which indicated that strains with two integron structures were detected simultaneously and class 3 integron was not detected. Class 1 integron inserted gene cassette was mainly blaara30 -aadA 1 family, conferring resistance to β-lactamase, spectinomycin and streptomycins isolates carried class 2 integron were mainly dfrAl-satl genes cassettes conferring resistance to methoxybenzyl aminopyrimidine and streptothricin, while dfrA\-sat\-aadA\ genes were present only in 4 isolates. Conclusions These data indicate that class 2 integrons are widespread in Shigella dysenteriae strains, and closely associated with multidrug resistance of Shigella.