嗜麦芽寡养单胞菌β-内酰胺酶及喹诺酮类耐药基因检测

Detection of β-lactamase and quinolone resistance genes in Stenotrophomonas maltophilia

目的检测临床分离嗜麦芽寡养单胞菌耐药基因型并分析其与耐药表型的关系,从而为嗜麦芽寡养单胞菌感染的防治提供理论依据和对策。方法对2005—2008年收集的102株嗜麦芽寡养单胞菌提取全基因组DNA,采用PCR方法检测β-内酰胺酶L1、L2型耐药基因和喹诺酮耐药基因qnr,分析耐药基因与耐药表型的关系。结果 102株嗜麦芽寡养单胞菌对临床常用抗菌药物耐药率以替卡西林/克拉维酸最高达到42.16%,其次为复方磺胺甲基异噁唑29.41%、氯霉素27.45%、头孢他啶22.55%,对米诺环素的耐药率最低11.76%。102株嗜麦芽寡养单胞菌L1基因阳性率76.47%,L2基因阳性率67.65%;其中L1和L2型基因共同阳性率56.86%;头孢他啶及替卡西林/克拉维酸耐药菌株均检测到L1和L2型基因。102株qnr X、qnr Y和qnr Z的阳性率都是100%。结论本地区嗜麦芽寡养单胞菌β-内酰胺酶L1和L2酶检出率较高,喹诺酮耐药基因qnr阳性率达到100%,染色体上Qnr酶单独存在并不会导致对氟喹诺酮类药物高度耐药。

Objective To detect the β-lactamase L1, L2 genes and quinolone resistance gene qnr in clinical isolated Stenotrophomonas maltophilia bacteria, which can offer the theoretical basis and measures to prevent and control Stenotrophomonas rnaltophilia infection. Methods According to a standard procedure described by the Clinical and Laboratory Standards Institute （CLSI）, 2010, the susceptibility test to 102 clinical S. maltophilia isolates from 2005 to 2008 against 6 antimicrobial agents was performed by means of agar dilution method. Total DNA of the 102 clinical isolates was extracted by suspending several overnight colonies in 0.5mL of double-distilled water and heating the mixture at 100℃ for 10 min. Then the β-1actamase L1, L2 genes and quinolone resistance gene qnr were detected by PCR, and their contribution to resistance of antimicrobial agents were analysed. Results Among the 102 S. maltophilia isolates from 2005 to 2008 in this research, according to the antimicrobial susceptibility results, the resistance rate of ticareillin/elavulanic was up to 42.16%, followed by trimethoprim/sulfamethoxazole with 29.41%, chloramphenicol with 29.41%, ceftazidime with 22.55%, and the resistance rate of minocycline was to 11.76%. The positive rates of L 1 gene, L2 gene, and L 1, L2 genes together were 76.47%, 67.65% and 56.86% respectively, and the positive rates of qnrX gene, qnrY gene and qnrZ gene were all 100%. Conclusions The positive rates of L1 and L2 genes are high in this region. The chromosome-encoded quinolone resistance gene qnr is ubiquitous in all the isolates, and its contribution to fluoroquinolones is not found.