广东地区副猪嗜血杆菌的耐药性调查及遗传相关性分析

Investigation of antimicrobial resistance and genetic correlation analysis of Haemophilus parasuis isolated from Guangdong Province

对广东地区分离的副猪嗜血杆菌进行耐药性调查以及遗传相关性分析,以获得临床分离株的耐药性特征和耐药菌的传播扩散机制。采用微量肉汤稀释法测定了95株副猪嗜血杆菌对临床常用的18种抗菌药物的敏感性。用PC R方法检测6类抗生素耐药基因的携带情况,并运用脉冲场凝胶电泳(PFG E)对携带相关耐药基因的菌株进行遗传相关性分析。结果表明,所有测试菌株对头孢噻呋和头孢噻肟均表现出较好的敏感性;对左氧氟沙星、红霉素、氟苯尼考和青霉素敏感性下降,耐药率分别为3.2%、5.3%、7.4%和13.7%。同时也检测到较高的耐药水平,对甲氧苄啶+磺胺甲噁唑、恩诺沙星和头孢克洛的耐药率分别为83.2%、46.3%和36.8%;对四环素(23.2%)、氨苄西林(22.1%)、庆大霉素(21.1%)和环丙沙星(20.0%)表现为中等水平的耐药。在95株菌中,26株菌(27.4%)携带有耐药基因,共检出5种耐药基因,检出率依次为tet(B)(21.1%)、aph(3′)-Ⅰ(9.5%)、sul2(9.5%)、aad A 1(8.4%)和blaROB-1(6.3%),其中15株菌同时携带有2个以上的耐药基因。在这些耐药基因阳性菌中,PFGE分析结果显示出遗传背景的多样性,同时,也观察到小范围的克隆。

The aim of the study was to investigate the prevalence of antimicrobial resistance and genetic relationship of Haemophilus parasuis isolates from pigs in Guangdong Province,and to obtain their characteristics of antibiotic resistance and propagation mechanisms. A total of 95Haemephilus parasuis isolates were tested for antimierobial susceptibility against 18 antimierobial agents by the broth microdilution method. All strains were screened for resistance to six types of antibiotics by PCR and the genetic relationship of the isolates carrying resistance genes were analyzed by Pulsed-field gel electrophoresis（PFGE）.The results showed that all the isolates were susceptible to ceftiofur and cefotaxime,and had reduced susceptibility to levofloxacin,erythromycin,florfenicol and penicillin, with resistance rates of 3.2%,5.3%,7.4%and 13.7%,respectively. However,high degree of resistance was observed for trimethoprim-sulfamethoxazole（83.2 % ）,enrofloxacin（46.3%）and cefaclor（36.8 % ）. Intermediate level of resistance was encountered for tetracycline（23.2%）,ampicillin（22.1%）, gentami- cin（21.1%） and ciprofloxacin（20.0 % ）.In 95 strains,26 （27.4%） isolates were positive,and 5 types of resistance genes were found. The resistance genes tet（B）,aph（3＇）- Ⅰ ,su12,aad A1 and bla SOB-1 were detected in 21.1% ,9.5% ,9.5% ,8.4% and 6.3% of the isolates,and 15 strains carried more than two resistance genes. Among those positive isolates,the PFGE profiles showed great genomic heterogeneity. However,it was also found that clonal spread did occur on a small scale.