A Study on the Distribution and Structure of ClassⅠIntegron and ISCR1 in Clinical Isolates of Acinetobacter Baumannii / 天津医药

ABSTRACT

Objective To investigate the distribution and the antibiotic resistance genes carried by classⅠintegron and insertion sequence common region(ISCR1)among clinical isolates of Acinetobacter baumannii. Methods Fifty-one clinical isolates of multidrug-resistant Acinetobacter baumannii were collected. Polymerase chain reaction method was used to detect the classⅠintegrase gene, variable region of classⅠintegron, ISCR1 and genes related to antibiotics resistance lo-cated downstream of ISCR1 in 51 multidrug-resistant Acinetobacter baumannii. Antibiotics resistance genes carried by classⅠintegron and ISCR1 were performed by DNA sequencing. The relationship between classⅠintegron and ISCR1 was detected by PCR-mapping. Results Among 51 multidrug-resistant Acinetobacter baumannii isolates, 45 strains were found con-taining classⅠintegrase genes, 32 strains were found containing variable regions. Sequencing results showed that the gene cassette arrays were aacA4-catB8-aadA1, aacC1-orfA-orf-B-aadA1 and blaPSE-1-aadA2-cmlA1-aadA1. Twenty-two strains were found containing ISCR1 and 5 strains were found containing resistance genes located downstream of ISCR1. DNA sequencing results showed the resistant gene of qnrA1-ampR. The results of PCR-mapping showed that ISCR1 located directly downstream of 3' conserved segment of classⅠintegron in 20 Acinetobacter baumannii strains. Conclusion ClassⅠintegron and ISCR1 play an important role in mechanisms of drug resistance of Acinetobacter baumannii. ClassⅠintegron and ISCR1 could connect in series in Acinetobacter baumannii.