嗜水气单胞菌国内分离株的毒力因子分布与致病性相关性分析

The Analyse of Virulence Factors-Pathogenicity Relationships of Aeromonas hydrophila Strains Isolated from China

为了研究分析国内致病性嗜水气单胞菌的毒力因子的分布及与致病性的相关性及其防治,选取5种主要毒力因子气溶素(aerA)、溶血素(hlyA)、丝氨酸蛋白酶(ahpA)、抗金属蛋白酶(ast)、肠毒素(altA)设计5对特异性引物,用PCR方法进行检测,采用急性毒性实验方法测定菌株对异育银鲫的半数致死量(50%lethal dose,LD50),细菌药物敏感试验纸片扩散(K-B)法检测对抗生素的敏感性,结果显示:除菌株Hong12的LD50约为109 cfu,毒力弱外,其他毒力均较强,LD50均在106 cfu左右。aerA、ahpA、hlyA、altA、ast 5种毒力基因的携带率分别为77.8%、88.9%、100%、100%、77.8%。通过比较嗜水气单胞菌毒力基因的分布情况与其对鲫鱼致病性试验结果可以发现,aerA、ahpA为嗜水气单胞菌致病的主要毒力因子,与致病性存在相关性,ast与致病力存在一定相关性,但不是主要毒力因子,hlyA、altA与致病性不存在相关性。9株嗜水气单胞菌对青霉素、羧苄青霉素、万古霉素不敏感,对复合磺胺、头孢噻肟、利福平中毒敏感,对呋喃妥因、氯霉素、四环素、氧氟沙星高度敏感。

To investigate the virulence factors-pathogenicity relationships of A eromonasLhydrophila, five virulence factors named the aerolysin （aerA）, hemolysin （hlyA）, extracelluar protease （ahpA）, enterotoxin （altA）, Anti metalloproteinases （ast） were detected by PCR amplification. The LD50 was quantified by acute toxic test on Carassais auratus gibebio; antimicrobial susceptibility test was used the Kirby-Bauer method. Except that the pathogenicity of Hong 12 of which the LD50 with 10^9 cfu/mL is weak, the other eight strains are all strong relatively, of which the LD50 are all around 10^6 cfu/mL. Presence of aerA, ahpA, hlyA, altA and ast. virulence genes was identified among 77.8%, 88.9%, 100%, 100% and 77.8% of tested strains, respectively. By comparing the results of the detection of virulence genes and the results of acute toxicity test of the A. hydrophila on Carassais auratus gibebio, it was found that the association of aerA and ahpA should be considered as a possible virulence marker, highly related to he pathogenicity; and ast may be related to the pathogenicity; however, neither hlyA nor altA is related to pathogenicity. The 9 strains bacteria were all identified as A. hydrophila by means of biochemical and molecular identification. They were found 100% insensitive to penicillin, carbenicillin, yancomycin; moderately sensitive to syntactic, sulfonamide, cefotaxime, rifampicin; all highly sensitive to furantoin, chloromycetin, acheomycin, ofloxacin.