鳗鲡源气单胞菌毒力基因及其耐药性分析

Virulence genes and antimicrobial resistance of Aeromonas spp.from eel Angulla spp.

为了解鳗鲡(Angulla spp.)源气单胞菌(Aeromonas spp.)潜在致病性及其耐药状况,选取近年来从患病鳗鲡肝、肾、脾及病灶等处分离的41株气单胞菌,通过扩增其16S rRNA及保守基因gyr B、rpo D序列进行病原菌鉴定,利用微量肉汤稀释法检测病原菌对9种抗菌药物的敏感特性,并通过PCR和SYBR Green qPCR方法分别检测其7种毒力基因及15种耐药基因的携带情况。结果表明:41株气单胞菌中有维氏气单胞菌(A.veronii)27株、嗜水气单胞菌(A.hydrophila)6株、达卡气单胞菌(A.dhakensis)5株、双壳气单胞菌(A.bivalves)2株和豚鼠气单胞菌(A.caviae)1株;毒力基因分析显示,alt的阳性检出率最高(75.6%),其余毒力基因显示不同的携带率,且56.1%的气单胞菌至少携带3种及以上的毒力基因;耐药性分析显示,气单胞菌对甲砜霉素、氟苯尼考完全耐药(100%),3重及以上耐药的菌株占100%,最多同时耐受8种抗菌药物;耐药基因分析显示,酰胺醇类floR、cmlA、磺胺类sul 1和氨基糖苷类aac(6′)-Ib为主要耐药基因,检出率均为100%,100%的菌株携带6重及以上耐药基因,最高的携带12重耐药基因(9.8%)。研究表明,鳗鲡源气单胞菌对酰胺醇类药物完全耐药,多重耐药情况较为严重,且大部分菌株同时携带多种毒力基因和耐药基因,耐药基因与耐药表型的检测结果不完全一致。

In order to research the potential pathogenicity and antimicrobial resistance of Aeromonas spp.isolated from eel Angulla spp.,a total of 41 strains of Aeromonas spp.isolated from the liver,kidney,spleen and lesions of the diseased Angulla spp.in Fujian were identified by sequencing analysis of 16S RNA,gyr B,and rpo D.Further,the drug sensitivities to 9 antibacterial drugs were detected using the microbroth dilution method and,virulence genes and resistance genes carrying were detected by PCR and SYBR Green qPCR.The results showed that the 41 isolates were identified as Aeromonas veronii(n=27),A.hydrophila(n=6),A.dhakensis(n=5),A.bivalves(n=2),and A.caviae(n=1).Virulence gene analysis revealed that the positive detection rate of alt was as high as 75.6%,and the remaining virulence genes showed different carrier rates,and 3 or more virulence genes were detected in 56.1%of Aeromonas spp.Resistance analysis showed that Aeromonas spp.strains were completely resistant to thiamphenicol and florfenicol(100%),with approximately 100%of these strains resistant to 3 or more,and up to 8 antibacterial drugs at the same time.Drug resistance gene analysis showed that floR,cmlA,sul 1,and aac(6′)-Ib were the main resistance genes,with detection rate of 100%,and all strains carrying 6 or more resistance genes,with the most 12 resistance genes(9.8%)in one strain.The virulence genes and antimicrobial resistance of Aeromonas spp.from Angulla spp.were shown to be completely resistant to thiamphenicol and florfenicol.Most strains carried multiple virulence genes and drug resistance genes at the same time,while the detection results of the drug resistance genes and drug resistance phenotypes were not completely consistent.The finding provides reference with the effective prevention and control of Aeromonas spp.