Resistance to antibiotics and distribution of tetracycline resistance determinants in haemophilus parasuis from pigs in south china | 华南地区副猪嗜血杆菌的耐药性特点及四环素耐药基因携带情况

Chino. 目的副猪嗜血杆菌(Haemophilus parasuis，HPS)是危害世界养猪业的重要细菌性病原菌之一，了解副猪嗜血杆菌临床分离株的耐药性特点和四环素耐药基因的携带情况，为临床上该病的防控提供科学依据。方法参考CLSI推荐的肉汤微量稀释法检测副猪嗜血杆菌华南分离株对21种抗菌药物的耐药性，用PCR方法检测9 种四环素耐药基因的携带情况，并利用脉冲场凝胶电泳（PFGE）分子分型技术对携带四环素耐药基因的菌株进行了遗传相关性分析。结果结果显示：被检菌株对磺胺类、喹诺酮类、四环素类、氨基糖苷类抗菌药物表现较强的耐药性，尤其对磺胺类药物的耐药率高于80%；对头孢菌素类药物比较敏感；菌株都耐受3种或3种以上的抗菌药物，其中以7重和8重耐药菌株的数量最多，分别占19.13%和17.39%。2008-2010年华南地区副猪嗜血杆菌的耐药性总体上呈现逐年上升的趋势。15.62%（18/115）的菌株携带tetB基因，这些菌株之间表现明显的遗传差异性，但是部分菌株存在克隆传播关系。结论副猪嗜血杆菌对抗菌药物的耐药性比较高，tetB基因在耐四环素的副猪嗜血杆菌中广泛存在，表明主动外排泵作用可能是副猪嗜血杆菌对四环素产生耐药性的主要机制。本研究有助于了解副猪嗜血杆菌耐药性的变化特点，并初步揭示了该菌对四环素的耐药机理。

Inglés. Objective Haemophilus parasuis is one of the most frequent pathogenic bacteria which has caused a serious of problems in pig industry all over the world. Therefore, it is important to evaluate the resistance to antibiotics and the distribution of tetracycline resistance determinants in H. parasuis from pigs in order to prevent and control this diseases. Method All H. parasuis were isolated from clinically diseased pigs and antimicrobial susceptibility to 21 antibiotics was performed using the broth microdilution method, and PCR was used to detect the presence of 9 tetracycline resistance genes. Then genetic relationship of the isolates which had tetracycline resistance was analyzed by Pulsed-?eld gel electrophoresis (PFGE). Result Most of the H. parasuis isolates showed resistance to many antimicrobial agents commonly used in veterinary clinic such as sulfamethoxazole, ?uoroquinolones, tetracycline, and gentamicin. Especially, more than 80% of the isolates were resistant to trimethoprim and sulfamethoxazole. Cephalosporins showed a good activity to H. parasuis isolates. Overall, the antimicrobial resistance of H. parasuis isolated from South China between 2008 and 2010 has been rising. All isolates showed multiple-drug resistance, resistance to 7 and 8 antibiotics was the main trend, the percentage were 19.13% and 17.39%. Tetracycline resistance gene tetB was widespread in H. parasuis. Analysis of PFGE typing implied that the isolates represented a wide variety of chromosomal backgrounds. Conclusion The study showed high resistance to antibiotics in H. parasuis isolated from pigs in South China, and tetB gene was widespread. The efflux of the drugs may be the major resistance mechanism of H. parasuis to tetracycline. This study helps to grasp the trend of drug resistance, and reveals mechanism of bacteria resistance to tetracycline.