ABSTRACT
Objective:To determine the molecular characteristics of Streptococcus suis type 2 (SS2) in Zhejiang Province. Methods:Twenty-nine SS2 sporadic human isolates in Zhejiang Province from Januery 2005 to July 2021 were genotyped by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and minimum core genome (MCG) sequence typing.Results:Among 29 strains, 10 PFGE patterns and three main clusters were obtained by PFGE. Twenty-one (72.41%) of the strains were divided into two main branch groups and the remaining eight (27.59%) showed genetic diversity with the similarity ranging from 49.7% to 94.7%. Three sequence types were obtained from 29 strains by MLST, including ST7 (86.21%(25/29)), ST1 (10.34%(3/29)) and ST25 (3.45%(1/29)). In addition, three genotypes were obtained from 29 strains by MCG, including genotype E (41.38%(12/29)), genotype group 1 (55.17%(16/29)) and genotype group 4 (3.45%(1/29)).Conclusions:Two large clonal groups of highly pathogenic strains of SS2 have been prevalent in Zhejiang Province. A few strains display genetic diversity, indicating genetic variation may exist during transmission.
ABSTRACT
Objective@# To establish real-time recombinase polymerase amplification（RPA）for the rapid detection of Vibrio parahaemolyticus（VP）.@*Methods@#An exo probe and primers were designed according to the conserved sequence of thermolabile hemolysin（tlh）gene of VP and then RPA for detection of VP was established. The sensitivity of the assay was evaluated by detecting different concentration of VP;the specificity was evaluated by detecting different bacteria;the stability was evaluated by repeat trials;the application effect was evaluated by detecting food samples which were simultaneously tested with traditional culture method according to GB 4798.7-2013 Detection of VP.@*Results@#A real-time RPA was established to complete VP amplification within 20 min at a constant temperature of 39 ℃. The analytical sensitivity of the assay was five pg per reaction and no cross-reactivity with other pathogenic bacteria observed. The RPA detection results with different concentration of VP and E. coli DNA templates at three time points were consistent. The detection results of 51 food samples by RPA were the same as those by traditional culture method.@*Conclusion@#The established real-time RPA can qualitatively detect VP,with simple operation and interpretation of results,which is suitable for rapid detection of VP in public health emergencies and food safety supervision.