Study On Epidemiology Characterization Of Streptococcus Suis And Hp0197Genetic Diversity Analysis

Streptococcus suis is a Gram-positive facultative anaerobe pathogen, which can cause septicaemia, arthritis and meningitis, is the predominant agent about streptococcal disease in China, and have an measurable impact on pig industry. A terrible Streptococcus suis infection break out in2005in China which lead to dozens of death, and pose a major threat for our public safety. There have been epidemiological analyses about407strains isolate in China between2003and2007, which include the Serotype, genotype and virulence. And a MIC test for126strains isolate between2003and2008was analyzed. And there is no any new nationwide analysis toward the epidemiological study since2007. So a new epidemiological study is analyzed for Streptococcus suis which isolate between2008and2012, including serotype test, antibiotic resistance and determination of genotypes and toxicity in mice of Streptococcus suis type3, we also analysis the relationship between virulence genes and antibiotic resistance, and genetic diversity of hp0197gene is analyzed in the study.1. Epidemiological study of Streptococcus suisComprehensive epidemiological study is to be analyzed, which include the Serotype, virulence genes, antibiotic minimal inhibitory concentration and determination of genotypes and toxicity in mice of Streptococcus suis type3. The result shows that1286strains are isolated and isolation rate is15.9%. the isolation rate of serotype2is higher significantly than other serotypes(P<0.01).The antibiotic resistance is detected in strains isolates from the diseased pigs in recent years. the result suggest that the resistance rate of Azithromycin, Erythromycin, Clindamycin and Tetracycline are more than89%, In addition to them, the antibiotic resistance rates of others are not more than20%, and22resistance profiles are found. PCR test is analyzed toward71virulence genes in27SS. We found that the numbers of virulence genes of multi-drug resistant(number of drug resistance is more than4) strains are less than low drug resistant (number of drug resistance is less than4)strains (P<0.01).There is a negative correlation between virulence genes and antibiotic resistance. A test of MLST genotype is used to anilysis these27strains, we found most multi-drug resistant strains can not be genotyped and serotyped and most of low drug resistant strains are ST1(ST7) and serotype2and3. Which suggest that multi-drug resistant strains are different from low resistant strains in serotype and genotype. 2. Serotype and resistance trends of Streptococcus suis.Compare the result of serotype distribution of SS isolation between2003and2012, we found that the isolate rate of Streptococcus suis serotype2has reduced, and serotype3has increased. Compare our datas with the antibiotic resistance of SS isolation between2003and2008, the result show that the number of resistance profile growth from11to22, and resistance profile which contain Azithromycin, Erythromycin, Clindamycin and Tetracycline growth from55.6%to69.4%, resistance profile which contain7,8,10or12antibiotic are found. The entire resistance rate of Cefaclor, cefepime, Cefotaxime, Cefuroxime, Azithromycin, Clindamyxin and Erythromycin increase that suggest antibiotic resistance rate of SS is more serious.3. Analyze of genotype and virulence of serotype3strainsThe result of determination of genotypes and toxicity in mice of66type3strains isolate between2008and2012show that most genotype of type3strains is mrp+sly+ef-, which account for83.3%, the strains which have mrp+sly+ef+, mrp-sly+ef-, mrp-sly-ef-genotype account for9.1%,4.5%and3.0%. Some type3strains (genotype mrp+sly+ef+) have virulence for mice, and there is a highly virulence serotype3strain for mice.4. Genetic diversity study of hp0197geneAn epidemiology study is analyzed for the new virulence factor hp0197gene.13genomes are used to analysis hp0197genes. A PCR test is used to identify genetic diversity of hp0197gene for56strains and36strains have hp0197genes. Hp0197genes exists in1/2、1、2、3、4、5、7、8、9、11、14、17、18、19、23、25、29、33type and not typing strains, and lots of genetic diversity are found. All of17type2strains present hp0197genes and15of these are1686bp, their similarity greater than99%, which suggest hp0197genes in type2is highly conserved. It may be identified as a new target for type2identification.