Analysis on the main virulence genes and molecular typing of non-O1/non-O139 Vibio cholerae in bloodstream infection

Abstract

Objective To analyze the virulence genes and molecular typing of non-O1/non-O139 Vibio cholerae in bloodstream infection, and to provide the scientific basis for its diagnosis, treatment, prevention and controls. Methods Five Vibio cholerae strains were obtained from blood samples of five inpatients with sepsis in Ruian People’s Hospital from 2012 to 2015. Morphological examination, biochemical identification, drug sensitivity test and multilocus sequence typing (MLST) classification analysis of strains were conducted. Totally 17 virulence genes were detected by PCR amplification. Results These five suspected Vibrio cholerae isolates were confirmed as non-O1/non-O139 Vibrio cholerae. Drug susceptibility test showed that all the strains were sensitive to tetracycline, ciprofloxacin, piperacillin and tazobactam, meropenem, amikacin and gentamicin; one strain was resistant to trimethoprim/sulfamethoxazole; all were resistant to ampicillin. MLST analysis showed that all strains were new sequence types (ST), belonging to ST268, ST269, ST267, ST270 and ST271, and two novel alleles of RY03(mdh: 60 and pyrC: 86) were discovered. Virulence genes testing showed that the five strains were divided into 4 virulence genotypes: RY02 and RY04 (hlyA+toxR+hap+rtxA+nanH+vasH+vasA+vasK+ ), RY01 (hlyA+toxR+hap+rtxA+nanH+vasH-vasA+vasK-), RY03 (hlyA+toxR+hap+rtxA+nanH-vasH+vasA+vasK+ ) and RY05(hlyA+toxR+hap+rtxA+nanH+vasH-vasA-vasK-). Conclusions Non-O1/non-O139 Vibrio cholerae can cause human bloodstream infection in immunocompromised patients. The pathogenic factors may be related to the virulence genes of hlyA, toxR, hap, rtxA and T6SS. Key words: Vibrio cholerae; Non-O1/non-O139; Bloodstream infection; Multilocus sequence typing; Virulence gene