湖北、江苏团头鲂源嗜水气单胞菌致病性与药敏特性研究

对湖北、江苏两省的8个团头鲂主养区分离的嗜水气单胞菌的致病性和药敏特性进行比较，分析不同地区嗜水气单胞菌在致病力和耐药性方面的差异。结果表明：气溶素基因(aer)、丝氨酸蛋白酶基因(ahp)、溶血素基因(hly)、抗金属蛋白酶基因(ast)、肠毒素基因(alt)在各菌株中的携带率分别为100%(8/8)、75%(6/8)、87.5%(7/8)、100%(8/8)、75%(6/8)，仅E6、X22分别缺少ahp、alt基因和ahp、hly、alt基因；6株均携带上述5个毒力基因的菌株，其中有5株菌的溶血价和溶蛋白效价均达到最高的1:128，W25为1:128、1:64，E6和X22分别是1:64和1:64、1:32和1:64；上述6株菌的LD50值在5.0×105~1.0×106 cfu/mL之间，E6和X22的LD50值分别为2.4×106 cfu/mL和4.0×106 cfu/mL；不同地区的嗜水气单胞菌对孢头菌素类、氟苯尼考高度敏感，对青霉素类高度不敏感，对氨基糖苷类、磺胺类呈现一定程度的耐药性；江苏省分离菌株对恩诺沙星、四环素的耐药性明显高于湖北省的分离株，而湖北省分离株对新生霉素的耐药性要高于江苏省的分离菌株。可以得出，不同地区的菌株致病力没有显著差异，而在耐药性方面呈现一定的区域差异性。

Studies on Pathogenicity and Drug-resistance Characteristics of Aeromonas hydrophila Isolated from Megalobrama amblycephala in Hubei and Jiangsu Province

Pathogenicity experiment and drug sensitivity characteristics of 8 Aeromonas hydrophila strains isolated from Megalobrama amblycephala collected in Jiangsu and Hubei Province were investigated. The results showed that presence of aer, ahp, hly, ast and alt virulence genes was 100%(8/8), 75%(6/8), 87.5%(7/8), 100%(8/8) and 75%(6/8) of tested strains, respectively. The strain E6 has not observed ahp, alt genes and strain X22 has not observed ahp, hly, alt genes. A total of 6 strains were recorded with all above virulence genes, among 5 strains the hemolytic and proteolytic were up to 1:128, 1:128 and 1 strain the hemolytic and proteolytic were up to 1:128, 1:64, respectively. The hemolytic and proteolytic of E6 and X22 were 1:64, 1:64; and 1:32, 1:64, respectively, which were lower than others. The LD50 for M. amblycephala of the 6 strains were from 5.0×105 to 1.0×106 cfu/mL. The LD50 of another 2 strains E6 and X22 was 2.4×106 cfu/mL and 4.0×106 cfu/mL, respectively. The 8 strains showed highly sensitive to fluoroquinolones, cephalosporins, resistant to penicillins, and certain extent resistance to aminoglycosides and sulfonamides. The strains isolated from Jiangsu Province showed more resistant than the strains isolated from Hubei Province to enrofloxacin and tetracycline. The strains isolated from Huhei Province showed more resistant than the strains obtained from Jiangsu Province to novobiocin. It suggested that the strains isolated in Hubei and Jiangsu Province were no significant differences in pathogenicity, while presented certain regional difference in drug resistance.