食品与环境中豚鼠气单胞菌系统发育分析以及毒力和耐药性研究

目的食品与环境中49株豚鼠气单胞菌菌种鉴定、毒力与耐药性检测。方法VITEK、API 20NE生化鉴定,gyrB、rpoD系统发育分析;PCR检测act、alt、ast、lip、ahp、aerA、hlyA、ompA1、fla基因;AST-GN16药敏试验。结果生化鉴定为豚鼠/嗜水气单胞菌株54株,经系统发育分析豚鼠气单胞菌49株,嗜水气单胞菌4株,中国台湾省气单胞菌1株。毒力基因alt、lip、ompA1、fla、act、aerA、hlyA检出率依次为100.00%、100.00%、79.59%、14.29%、2.04%、2.04%、2.04%,未检出ast、ahp;存在4种毒力基因组合,优势组合为alt/lip/ompA1(32/49)。豚鼠气单胞菌氨苄西林、头孢唑林、头孢西丁、阿莫西林/克拉维酸、头孢曲松、复方新诺明、安曲南耐药率依次为79.59%、14.29%、10.20%、6.12%、4.08%、4.08%、2.04%,哌拉西林/他唑巴坦、亚胺培南、阿米卡星、庆大霉素、左氧氟沙星、替加环素、呋喃妥英均敏感;2株多重耐药菌株。结论gyrB、rpoD可有效鉴定豚鼠/嗜水气单胞菌,rpoD可区分近亲缘关系豚鼠与中国台湾省气单胞菌;所有豚鼠气单胞菌均携带2种以上毒力基因,1株环境源菌携带7种毒力基因;青霉素类普遍耐药,产生β-内酰胺酶是最主要耐药机制;未发现碳青霉烯类、氨基糖苷类、氟喹诺酮类、四环素类、呋喃类耐药菌株;食品和生活饮用水存在多重耐药菌。

Phylogenetic characteristics,virulence and antibiotic resistance of Aeromonas caviae isolated from foodborne and environmental samples

Objective To identify 49 Aeromonas caviae strains isolated form foodborne and environmental samples and analyze their virulence and antibiotic resistance.Methods All strains were identified by VITEK and API 20NE.Two housekeeping genes,gryB and rpoD,were amplified by PCR for phylogenetic analysis.Virulence genes including act,alt,ast,lip,ahp,aerA,hlyA,ompA1 and fla were detected by PCR.In vitro antimicrobial susceptibility of these strains was tested with AST-GN16 kit.Results Fifty-four Aeromonas caviae/Aeromonas hydrophila strains were identified by biochemical tests.Phylogenetic analysis revealed that there were 49 Aeromonas caviae strains,four Aeromonas hydrophila strains and one Aeromonas taiwanensis strain.The positive rates of alt,lip,ompA1,fla,act,aerA and hlyA genes were 100.00%,100.00%,79.59%,14.29%,2.04%,2.04%and 2.04%,respectively.None of the isolates carried ast or ahp gene.A total of four virulence gene combination patterns were detected,and the predominant pattern was alt/lip/ompA1(32/49).Antibiotic resistance rates of the Aeromonas caviae strains to ampicillin,cefazolin,cefoxitin,amoxicillin/clavulanic acid,ceftriaxone,trimethoprim/sulfamet hoxoazole and aztreonam were 79.59%,14.29%,10.20%,6.12%,4.08%,4.08%and 2.04%,respectively.All strains were susceptible to piparacillin/tazobactam,imipenem,amikacin,gentamicin,levofloxacin,tigacycline and nitrofurantoin.Two multidrug-resistant strains were detected.Conclusions Aeromonas caviae/Aeromonas hydrophila can be effectively identified by the housekeeping genes gyrB and rpoD,and the closely related Aeromonas caviae and Aeromonas taiwanensis strains can be identified by rpoD.All Aeromonas caviae strains carried two or more virulence genes and one strain isolated from environment was positive for seven virulence genes.Aeromonas caviae strains were generally resistant to penicillin,which was mainly relate to the production ofβ-lactamase.No strain was resistant to carbapenems,aminoglycosides,fluoroquinolones,tetracyclines or furans.Multidrug-resistant strains were observed in food and drinking water.