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

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 16s 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 16s 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.