上呼吸道分离鲍曼不动杆菌1 型整合子的分离与鉴定

【目的】研究I型整合子的结构特征,探讨其与细菌多重耐药之间的相关性。【方法】收集2008年至2009年广州呼吸疾病研究所上呼吸道分离的187株鲍曼不动杆菌,应用K-B纸片扩散法检测耐药性,采用聚合酶链式反应进行I型整合子整合酶基因的检测;扩增整合子的可变区,应用DNA测序技术分析I型整合子基因结构。【结果】I型整合子的阳性率达53.4%。共七种1型整合子基因盒被鉴定,其中首次发现报道一种新的整合子(GenBank:HQ322622)。可变区主要编码氨基糖苷类药物的耐药基因。20种抗菌素耐药的结果均表明携带Ⅰ型整合子的鲍曼不动杆菌耐药率较不携带I型整合子的鲍曼不动杆菌的耐药率明显增高。整合子与鲍曼不动杆菌的多重耐药表型具有密切相关性。【结论】I类整合子相关耐药基因在本院临床分离鲍曼不动杆菌中分布较广泛。整合子在鲍曼不动杆菌耐药性的形成和播散中具有重要作用。

Characterized of class I integron in Acinetobacter baumannii isolated from upper respiratory tract

Objective] To characterize the class Ⅰ integron in Acinetobacter baumannii and to analyze the correlation between integron and drug resistance.Methods] In total 187 strains were collected between 2008 and 2009.All strains were tested by Kirb-Bauer disk diffusion test for drug resistance.PCR and DNA sequencing were used to detected classⅠintegrase gene and to clarify the context of gene cassette.Results] ClassⅠ integrase gene was detected in 100(53.4%) of the isolates analyzed.Seven different gene cassettes were identified,including a new integron(GenBank:HQ322622) carrying an unknown protein probably associated with recombination.The vast majority of the cassettes encoded amonoglycoside resistance gene,including aacA4,aadA1,aacC1,aac6Ⅱ,aadA2.Susceptibility data show that strains carrying classⅠintegron were significantly more resistant to all of the antibiotics tested than isolates lacking classⅠintegron.The correlation between the presence of integron and the multidrug-resistance of A.baumannii was statistically significant.Conclusion] Drug resistance genes integrated by Class Ⅰ integron were widespread in A.baumannii.ClassⅠ integron plays an important role in resistance of A.baumannii.