Virulence and molecular epidemiological analysis of three human blood-borne .

OBJECTIVE

To understand the virulence genes and molecular epidemiological characteristics of human-infected strains of in Rui'an, Zhejiang Province, from 2021 to 2022, and to provide a scientific basis for diagnosis, treatment, prevention, and control.

METHODS

Three blood-borne strains of were analysed by morphological observation, identification, and drug sensitivity tests. We performed polymerase chain reaction (PCR) amplification of their main seven virulence factors and housekeeping genes. This was followed by virulence analysis and multilocus sequence typing. We analysed their relationships with local pathogens from previous years.

RESULTS

Three strains were isolated from the blood samples of three patients. From these, the virulence genotypes demonstrated that the two strains were and +, respectively. The Multilocus sequence typing (MLST) typing results demonstrated that the two strains were and respectively.

CONCLUSION

The first isolation of in Rui'an was presumed to have a close affinity with the endemic strain in North America. The other strain was an clone, consistent with the endemic strain in Sichuan, and which may have originated from Sichuan. Virulence genotype analysis demonstrated that different virulence genes of the pathogens resulted in different clinical manifestations.