一株携带三型分泌系统vcsN2基因的非O1/O139群霍乱弧菌的鉴定、药敏及致病性分析

A non-O1/O139 Vibrio cholerae carrying the vcsN2 gene of the three-type secretion system:identification,drug susceptibility and pathogenicity analysis

目的了解携带三型分泌系统vcsN2基因的非O1/O139群霍乱弧菌的耐药及致病性特征。方法对疑似霍乱弧菌感染的腹泻患者粪便进行培养,采用VITEK 2 Compact自动化鉴定药敏仪进行生化鉴定,最后通过提取细菌的16s rDNA,经测序后进行同源性比对。采用K-B法检测霍乱弧菌的耐药性,PCR法对霍乱弧菌的毒力相关基因进行检测。结果分离菌在弧菌显色培养基中呈现蓝绿色菌落特征,在血琼脂平板中为伴有溶血的乳白色菌落,氧化酶阳性,镜下见两端钝圆、弯曲的革兰阴性杆菌,生化鉴定为霍乱弧菌。经16s rDNA测序后进行同源性比对,相似性为99.79%。经血清凝集试验显示为非O1/O139群霍乱弧菌。药敏结果显示,该菌株对大部分抗生素敏感,其中包括复方新诺明、阿米卡星、左氧氟沙星、环丙沙星、氨苄西林、头孢吡肟、头孢曲松、四环素、庆大霉素,对头孢唑林、克林霉素、亚胺培南表现为耐药。毒力检测结果显示除携带有三型分泌系统vcsN2基因外、还携带rtxC、hlyA、toxR、ompW,而检测的O1/O139的rfb、tcpA、ctxA、chx均为阴性。结论这株临床分离的非O1/O139群霍乱弧菌携带的毒力基因较多,需加强肠道门诊腹泻患者非O1/O139群霍乱弧菌毒力及耐药基因的检测,为霍乱弧菌的防控救治提供一定的参考依据。

Objective To explore the drug resistance and pathogenic characteristics of non-O1/O139 Vibrio cholerae carrying the vcsN2 gene of the three-type secretion system.Methods The stool samples of patients with diarrhea with suspected Vibrio cholerae infection were cultured.An VITEK 2 Compact automatic identification drug susceptibility instrument was used for biochemical identification.Finally,the 16 s rDNA of the bacteria was extracted and sequenced for homology comparison.The drug resistance of Vibrio cholerae was detected by the K-B method,while the virulence-related genes of Vibrio cholera was amplified by PCR.Results The isolated bacteria showed the characteristics of blue-green colony in the Vibrio chromogenic medium.In the blood plate,a milky white colony with hemolysis was presetned,which was positive for oxidase;obtuse round and curved gram-negative bacilli at both ends were seen under a microscope.According to biochemical identification results,the stain was Vibrio cholerae.After 16 s rDNA sequencing,homology comparison was performed,which indicated a similarity of 99.79%.The serum agglutination test showed that it was non-O1/O139 Vibrio cholerae.Drug sensitivity results showed that the strain was sensitive to most antibiotics,including compound trimethoprim,amikacin,levofloxacin,ciprofloxacin,ampicillin,cefepime,ceftriaxone,tetracycline,and gentamicin.It was resistant to cefazolin,clindamycin and imipenem.The virulence test results showed that in addition to the vcsN2 gene of the three-type secretion system,it also carried rtxC,hlyA,toxR,and ompW.The detected O1/O139 rfb,tcpA,ctxA,and chx were all negative.Conclusions The isolated strain of non-O1/O139 Vibrio cholerae carries many virulence genes.It is necessary to strengthen the detection of non-O1/O139 Vibrio cholerae virulence and drug resistance genes in patients with intestinal outpatient diarrhea,so as to provide evidence for the prevention,control and treatment of the bacteria.