临床分离志贺菌耐药性分析及1类整合子的检测

Detection of antimicrobial resistance and class 1 integron among clinical isolates of Shigella

目的了解2007年至2010年安徽省临床分离志贺菌耐药性和1类整合酶基因(intⅠ1)、qacE△1-sul1基因及整合子携带的耐药基因盒的分布。方法琼脂稀释法检测21种抗菌药物对志贺菌的最低抑菌浓度。PCR扩增intⅠ1和qacE△1-sul1基因,对阳性菌株可变区基因盒序列进行分析。结果 137株志贺菌对萘啶酸、氨苄西林、磺胺甲噁唑/甲氧苄啶的耐药率均80.0%以上,且多重耐药率达94.2%,但对三代头孢菌素和氟喹诺酮类耐药率在33.0%以下。intⅠ1的检出率为89.1%(122/137),检出dfrA17-aadA5和aar-3-aacA4两种基因盒,首次在志贺菌中检测到aar-3-aacA4基因,GenBank登录号JF271916。结论安徽省临床分离志贺菌多重耐药现象严重。临床仍可选用氟喹诺酮类和三代头孢菌素作为本地区细菌性痢疾的经验性治疗。1类整合子与志贺菌的耐药具有一定的相关性。

Objective To investigate the distribution of intI1 integrase gene, qacE/ΔI-sull gene and gene cassettes embedded in shigella clinical isolates. Methods Antimicrobial susceptibility testing was performed by agar dilution method. The presence of class 1 integron and resistance genes was detected by polymerase chain reaction （PCR）. The array of gene cassettes was determined by DNA sequencing. Results Antimicrobial susceptibility testing showed a high level of resistance to nalidixic acid （97.8%）, ampicillin （93.4%）, and co-trimoxazole （81.0%）. Although high prevalence of multidrug resistance （94.2%） was identified, less than 33.0% of the Shigella isolates tested was resistance to fluoroquinolones and the third generation cephalosporins, int11 gene was detected in 122 （89.1%） isolates and two types of class 1 integron structures were identified in this study. The identified gene cassettes within class 1 integron were as follows： dfrA17-aadA5, which confer resistance to trimethoprim and streptomycin/ spectinomycin, respectively; aar-3-aacA4, which confer resistance to rifampin and aminoglycosides, respectively. The gene was submitted to the GenBank database, and the accession number was JF271916. Conclusions The situation of multidrug resistance in Shigella isolates is fairly serious, and the existence of class 1 integron plays an important part in drug resistance. Fluoroquinolones and the third generation cephalosporins still can be used in treating patients infected with Shigella as empirical therapy.