安徽地区嗜麦芽寡养单胞菌中整合子及ISCR1流行情况研究

The prevalence studies of integrons and ISCR1 of Stenotrophomonas maltophilia in Anhui area

目的了解安徽省2010—2013年嗜麦芽寡养单胞菌(SMA)临床分离株的整合子和ISCR1及其携带的耐药基因情况,并初步探究其与耐药性的关系。方法应用PCR扩增qac E△1-sul1基因、int I、int II、int III、I类整合子可变区、ISCR1基因及ISCR1可变区耐药基因;对临床分离株采用琼脂倍比稀释法测定药物的最低抑菌浓度。结果 115株嗜麦芽寡养单胞菌中Int I的检出率为64.3%,ISCR1的检出率为4.3%,未检测到II类、III类整合子。I类整合子可变区检出aac A4-cat B8-aad A1和aac(6’)-IIblaCARB-8两类基因盒,检出率分别为6.8%和2.7%,ISCR1可变区未检出耐药基因。I类整合子的检出在多重耐药株与非多重耐药株中的差异有统计学意义(P<0.01)。sul1阳性组和Int I阳性组中甲氧苄啶/磺胺甲噁唑的耐药程度均要明显高于两者均阴性的一组。结论 I类整合子及sul1基因的存在可以加重SMA对甲氧苄啶/磺胺甲噁唑的耐药性。本地区I类整合子与ISCR1的检出可能有助于SMA的多重耐药性及耐药基因的传播。

Objective To learn the presence of integrons, ISCR1 and the resistance genes they carried and to explore its relationship with resistance among 115 clinical strains of Stenotrophomonas maltophilia which were isolated from Anhui Province from 2010 to 2013. Methods The amplification of qacE△1-sullgene, class 1, 2 and 3 integrase, variable region of class 1 integron and ISCR1 as well as ISCR1 gene were detected by polymerase chain reaction （PCR）. Minimal inhibitory concentrations of 19 antimicrobial agents were determined by agar dilution method. Results 74 strains（64.3%） of 115 Stenotrophomonas maltophilia were intI gene positive; the number of ISCR1 positive strains was only 5 （4.3%）. No Class 2 and 3 integron were detected. 6.8%（5） aacA4-catBS-aadA1 gene cassette and 2.7%（2） aac（6＇）-II-blacgRB-8 gene cassette were identified in intI positive strains. Resistance gene was not detected in the variable region ofISCR1. The detected rate of class 1 integron in multi-drug resistance （MDR） isolates was higher than non-MDR isolates （P〈0.01）. The MIC values of class 1 integron positive group and sull gene positive group were significantly higher than the group that class 1 integron and sull gene both were negative among the trimethoprim-sulfamethoxazole （TMP/SMZ） resistant strains. Conclusion This study showed that the presence of class 1 integron and sull gene in Stenotrophomonas maltophilia isolates can enhance their resistance to TMP/SMZ. Class 1 integron and ISCR1 may increase the multi-drug resistance of SMA and accelerate the spreading of resistance genes in Anhui province.