Two new gene cassette combination in multi-drug resistant Pseudomonas aeruginosa integron

Objective To investigate the carrying integron types and the gene cassette combination in multi-drug resistant Pseudomonas aeruginosa.Methods Polymerase chain reaction(PCR) were carried out to detect The integrase gene intI1,intI2 and intI3,the genes of constant and variable region of class I integron qacEΔ1-sul1 were detected by polymerase chain reaction(PCR).PCR products were purified by agarose gel.The gene cassette combination was determined by restriction fragment length polymorphism(RFLP) analysis and sequencing.Results Positive amplifications of class I integrase gene and gene qacEΔ1-sul1 were presented in 16 strains(53.3%) of 30 Pseudomonas aeruginosa isolates,but no class Ⅱ and Ⅲ integrase gene were detectable.Five different combinations of gene cassettes were found in the variable region of class I integron,in which the resistant genes for aminoglycosides,β-lactams and quinolones antibiotics were covered.Among the 5 combinations of gene cassette aacA4-VIM2 and aadA2-OXA10-aacA4-blaIMP-9-aatI1 were newly found with the accession numbers of GQ89065 and GU122165 in GenBank respectively.The other 3 gene cassette combinations were basically matched with the accession number FJ917747,FJ817423 and GU367339 respectively in GenBank.Conclusion Multi-drugs resistant Pseudomonas aeruginosa may primarily carriy class I integron,and two new gene cassette combinations were firstly found in class I integron.