鲍曼不动杆菌临床株Ⅰ类整合子和ISCR1的分布及结构研究

A Study on the Distribution and Structure of Class Ⅰ Integron and ISCR1 in Clinical Isolates of Acinetobacter Baumannii

目的了解鲍曼不动杆菌临床株中Ⅰ类整合子、插入序列共同区(ISCR1)的分布情况,研究它们所携带的耐药基因。方法收集来自临床的51株多重耐药鲍曼不动杆菌,PCR检测Ⅰ类整合酶基因、Ⅰ类整合子可变区、ISCR1和ISCR1下游基因环境,DNA序列分析检测Ⅰ类整合子和ISCR1携带的耐药基因,PCR-mapping检测Ⅰ类整合子与ISCR1的关系。结果 51株多重耐药鲍曼不动杆菌中Ⅰ类整合酶基因阳性45株,32株检出可变区结构,DNA序列分析显示携带aacA4-catB8-aadA1、aacC1-orfA-orfB-aadA1、blaPSE-1-aadA2-cmlA1-aadA13种形式的耐药基因盒;ISCR1阳性22株,5株检出ISCR1下游基因,DNA序列分析结果为qnrA1-ampR。PCR-mapping显示20株鲍曼不动杆菌中的ISCR1直接连接在Ⅰ类整合子3′保守区下游。结论Ⅰ类整合子、ISCR1在鲍曼不动杆菌耐药中起重要作用,且Ⅰ类整合子和ISCR1可以串联形式存在于鲍曼不动杆菌中。

Objective To investigate the distribution and the antibiotic resistance genes carried by class I integron and insertion sequence common region （ISCR1） among clinical isolates of Acinetobacter baumannii. Methods Fifty-one clinical isolates of muhidrug-resistant Acinetobacter baumannii were collected. Polymerase chain reaction method was used to detect the class ] integrase gene, variable region of class I integron, ISCR1 and genes related to antibiotics resistance lo- cated downstream of ISCR1 in 51 muhidrug-resistant Acinetobacter baumannii. Antibiotics resistance genes carried by class I integron and ISCR1 were performed by DNA sequencing. The relationship between class 1 integron and ISCR1 was detected by PC R-mapping. Results Among 51 muhidrug-resistant Acinetobacter baumannii isolates, 45 strains were found containing class I integrase genes, 32 strains were found containing variable regions. Sequencing results showed that the gene cassette arrays were aacA4-catB8-aadA1, aacCl-orfA-orf-B-aadA1 and blaPsE_l-aadA2-cmlAl-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 qnrAl-amptl. The results of PCR-mapping showed that ISCR1 located directly downstream of 3 conserved segment of class I integron in 20 Aeinetobacter baumannii strains. Conclusion Class I integron and ISCR1 play an important role in mechanisms of drug resistance of Aeinetobaeter bamnannii. ClassIintegron and ISCR1 could connect in series in Aeinetobaeter baumannii.