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Objective:To analyze the incidence of brucellosis and the genotypes of Brucella isolates or nucleic acids in Shaanxi Province, to get the epidemiological and molecular genetic characteristics, and to provide scientific basis for precise prevention and control of human brucellosis. Methods:Log into the Chinese Disease Control and Prevention Information System, collect the incidence data of human brucellosis of Shaanxi Province in 2020, and analyze the epidemiological characteristics. Bacteriology and PCR methods were used to identify the isolates or nucleic acids, and multiple locus variable-number tandem repeat analysis (MLVA) was used for molecular typing. BioNumerics (Version 7.6) software was used to analyze the results of MLVA.Results:In 2020, 1 086 cases of human brucellosis were reported in Shaanxi Province, the incidence rate was 2.80/100 000, involving 86 counties (districts), the epidemic peak was from March to September (865 cases), male-to-female ratio was 2.68 ∶ 1.00 (791 ∶ 295), 79.74% (866 cases) in the age group of 30 to 69 years old, and 83.43% (906 cases) of the cases were farmers. Biotype identification of 36 isolates showed that 4 isolates were mutant Brucella melitensis, 3 isolates were Brucella melitensis 1 and 29 isolates were Brucella melitensis 3. The 36 isolates and 7 nucleic acids were identified as Brucella by BCSP31-PCR and Brucella melitensis by AMOS-PCR. MLVA-16 genotyping, panel1 showed two genotypes: type 42 (1-5-3-13-2-2-3-2) and type 63 (1-5-3-13-2-3-3-2), panel2A showed 4-41-8 and panel2B showed high variability. Thirty-six isolates and 7 nucleic acids were divided into 33 genotypes, of which 27 genotypes were single isolates and 6 genotypes were shared. Conclusions:The situation of human brucellosis prevention and control in Shaanxi Province is grim. MLVA-16 is a mature genotyping method, which determines the existence of multiple genotypes of Brucella isolates or nucleic acids in Shaanxi Province, which can provide scientific information for precise prevention and control of human brucellosis, outbreak analysis and epidemiological traceability.
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Objective:To investigate the genetic diversity and molecular epidemiology of Bordetella pertussis in Shaanxi province, and analyze the possible reasons of resurgence in this region. Methods:We characterized clinical isolates collected during 2012-2017 using multilocus antigen sequence typing (MAST) and multilocus variable-number tandem repeat analysis (MLVA).Results:The circulating strains and vaccine strains were different in molecular characteristics. The majority (95%) of the isolates were typed as prn1/ ptxP1/ ptxA1/ fim3-1/ fim2-1. In addition, eight MLVA types (MTs) and eight PFGE profiles were identified, respectively. MT195, MT55 and MT104 were dominant and MT195 continually increased annually. Conclusions:The genetic characteristics of the current strains in Shaanxi province were different from those of the vaccine strain. The evolution through genetic variation might be one of the reasons for the recurrence of pertussis in this region.
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Objective@#To study the molecular-epidemiological characteristics of Brucella species isolated from different countries, using the multiple locus tandem-repeat (MLVA) analysis.@*Methods@#Eleven variable-number tandem-repeat (VNTR) loci were selected. VNTR strains of Brucella isolated from 48 different countries in 1953-2013, were analyzed by using the BioNumerics software. Unweighted Paired Arithmetic Average method was used to cluster and draw phylogenetic tree as well as the minimum spannin.@*Results@#The evolutionary relationship of Brucella phylogenetic tree was consistent with the classical biological typing method. However, the Brucella suis biovar 5 strains were different from the other Brucella suis biovars 1, 2, 3 and 4. Brucella ceti strains were divided into two parts and different from each other. Worldwide epidemics of brucellosis were emerged from 2005 to 2008 under the MLVA11 Orsay analysis. China has been a brucellosis-prone regions, with Brucella melitensis as the main epidemic Brucella species, followed by Brucella abortus. Brucella suis was mainly identified in the southern provinces, but Brucella canis was mainly found in dogs. No human cases were found.@*Conclusion@#Molecular-epidemiological characteristics of the Brucella strains were related to factors as time, region and hosts of isolation, which are important to setting up prevention and control programs on brucellosis.
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Objective To analyze the molecular characteristics of Brucella strains isolated from Nanjing,understand strains genotying and clustering,and to provide a basis for prevention and treatment of brucellosis.Methods Multilocus sequence typing (MLST) and multiple locus variable-number tandem repeat analysis (MLVA) were used to analyze and characterize Brucella ovis strains isolated from 7 cases of sporadic cases in Nanjing Drum Tower Hospital,the Affiliated Hospital of Nanjing University Medical School,from 2011-2016,and cluster analysis was did with reference strain data from Jiangsu Province.Results The results showed that 7 strains were defined as sequence type (ST) 8 by MLST.They were typed into 7 subtypes and clustered in the "Middle Mediterranean Cluster" by MLVA.Strain NJ-2011-1 and two strains isolated from other cities in Jiangsu had the same MLVA genotype.Conclusions The results reveal ST8 is the predominant genotype in Nanjing.They have clustered in the "Middle Mediterranean Cluster" by MLVA.The 7 strains are sporadic.The transmission routes and risk factors are more complicated in the city.Various departments should strengthen the cooperation to control the source.
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Two cross-sectional studies were carried out in 2013 and 2015 monitoring for Mycoplasma hyopneumoniae presence in a swine farm. In these studies, the genetic diversity of M. hyopneumoniae was assessed in clinical specimens using a Multiple Locus Variable-number tandem repeat Analysis (MLVA) targeting P97 R1, P146 R3 and H4 loci. The samples from August 2015 showed the MLVA profile prevalent in June 2013, therefore it can be concluded that a same genetic type of M. hyopneumoniae can persist for at least two years in a closed herd. In addition, the nested PCR reactions implemented in this study showed to be useful for MLVA typing in non-invasive clinical samples.
Dos estudios transversales fueron realizados en los anos 2013 y 2015 monitorizando la presencia de Mycoplasma hyopneumoniae en una piara. En esos estudios la diversidad genética de M. hyopneumoniae fue evaluada a partir de muestras clínicas utilizando un análisis multilocus de regiones repetidas en tándem (MLVA) de los loci P97 R1, P146 R3 y H4. Las muestras colectadas en agosto del 2015 mostraron el perfil de MLVA prevalente en junio del 2013, por lo tanto, se puede concluir que el mismo tipo genético de M. hyopneumoniae puede persistir por al menos 2 años en una piara sin reposición externa de animales. Además, las reacciones de PCR anidadas implementadas en este estudio mostraron ser útiles para la tipificación por MLVA a partir de muestras clínicas no invasivas.
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Animals , Mycoplasma hyopneumoniae , Pneumonia of Swine, Mycoplasmal , Swine , Genetic Variation , Cross-Sectional Studies , Minisatellite Repeats , Mycoplasma hyopneumoniae/isolation & purification , Mycoplasma hyopneumoniae/genetics , Pneumonia of Swine, Mycoplasmal/geneticsABSTRACT
Objective To understand the genotype of the Yersinia (Y.) pestis strains isolated from Heqing county,Yunnan province in 2017 and provide evidence for the prevention and control of plague in this area.Methods Ten Y.pestis strains isolated from Heqing were typed by the detections of different region (DFR) and clustered regularly interspaced short palindromic repeats (CRISPRs) as well as multiple-locus variable-number tandem repeat analysis (MLVA).And the results were compared with those of the 93 Y.pestis strains from the adjacent plague foci of Heqing obtained from the established database for clustering analysis.Results The results showed that Heqing strains had the same type of DFR (Genomovar 05) and CRISPRs (Cluster Ca7,Type 22) with isolates from the plague focus in Lijiang.Heqing strains and Lijiang strains were in the same cluster in MST and only VNTR loci N2117 and M23 of Heqing strains were different from that of Lijiang strains.Conclusion The Y.pestis strains isolated from Heqing in 2017 were highly homogenous with the strains isolated from wild rodents in plague focus in Lijiang,and Heqing plague might be the result of further southward spread of Lijiang plague.
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Objective To understand the genotype of the Yersinia (Y.) pestis strains isolated from Heqing county,Yunnan province in 2017 and provide evidence for the prevention and control of plague in this area.Methods Ten Y.pestis strains isolated from Heqing were typed by the detections of different region (DFR) and clustered regularly interspaced short palindromic repeats (CRISPRs) as well as multiple-locus variable-number tandem repeat analysis (MLVA).And the results were compared with those of the 93 Y.pestis strains from the adjacent plague foci of Heqing obtained from the established database for clustering analysis.Results The results showed that Heqing strains had the same type of DFR (Genomovar 05) and CRISPRs (Cluster Ca7,Type 22) with isolates from the plague focus in Lijiang.Heqing strains and Lijiang strains were in the same cluster in MST and only VNTR loci N2117 and M23 of Heqing strains were different from that of Lijiang strains.Conclusion The Y.pestis strains isolated from Heqing in 2017 were highly homogenous with the strains isolated from wild rodents in plague focus in Lijiang,and Heqing plague might be the result of further southward spread of Lijiang plague.
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Objective To investigate the genotype of M.tuberculosis in He'nan Province.Methods A total of 668 M.tuberculosis clinical strains collected in difference regions of He'nan Province during 2015 were genotyped by two standard methods,including classical 24-locus mycobacterium interspersed repetitive unit variable-number tandem-repeat (MIRU-VNTR) typing and spoligotyping.Results The 668 isolates were divided into 11 clusters and 35 patterns by spoligotyping.Among the 558 Beijing strains,546 were typical Beijing strains and the other 12 were atypical Beijing strains.Among the 110 non-Beijing strains,eight were new strains and the remaining 102 non-Beijing strains were divided into 10 families.There were 76 isolates belonging to T family,including 59 of T1 families,7 of T2 families,and 10 of T3 families.The 668 strains were divided into 550 gene patterns by standard 24-locus VNTR,including 508 un-clustered patterns and 160 clustered into 42 clusters.The largest cluster contained 21 strains,the other clusters contained 2-20 strains.Conclusion Beijing strain is still the most prevalent M.tuberculosis in He'nan Province.
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<p><b>OBJECTIVE</b>We determined the genetic diversity of Mycobacterium tuberculosis (MTB) in a remote mountainous area of southwest China and evaluated the resolving ability of single nucleotide polymorphism (SNP) genotyping combined with variable number tandem repeat (VNTR) genotyping for Beijing family strains in association with drug resistance status.</p><p><b>METHODS</b>Three hundred thirty-one MTB strains were isolated from patients living in mountainous regions of southwest China, and 8-loci SNP, VNTR-15 genotyping assays, and drug susceptibility testing of 9 drugs were performed.</p><p><b>RESULTS</b>A total of 183 [55.29% (183/331)] strains were classified into the Beijing family. Of the 183 strains, 111 (60.66%) were defined as modern Beijing strains. The most predominant modern Beijing sub-lineage and ancient Beijing sub-lineage were Bmyc10 [39.34% (72/183)] and Bmyc25 [20.77% (38/183)], respectively. Of the isolates, 19.64% (65/331) were resistant to at least 1 of the 9 anti-TB drugs and 17 [4.98% (17/331)] MTB isolates were multi-drug resistant tuberculosis (MDR-TB). Two hundred sixty-one isolates showed a clustering rate of 14.18% (37/261) and a discriminatory index of 0.9990. The Beijing lineage exhibited a significantly higher prevalence of MDR-TB, as well as resistance to isoniazid (INH), rifampin (RIF), and para-aminosalicylic acid (PAS) when analyzed independently (P = 0.005, P = 0.017, P = 0.014, and P = 0.006 respectively). The Beijing lineage was not associated with genetic clustering or resistance to any drug. In addition, genetic clustering was not associated with drug resistance.</p><p><b>CONCLUSION</b>MTB strains demonstrate high genetic diversity in remote mountainous areas of southwest China. Beijing strains, especially modern Beijing strains, are predominant in remote mountainous area of China. The combination of 8-loci SNPs and VNTR-15 genotyping is a useful tool to study the molecular epidemiology of MTB strains in this area.</p>
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Humans , Antitubercular Agents , Pharmacology , China , Epidemiology , Cluster Analysis , Drug Resistance, Bacterial , Genotype , Mycobacterium tuberculosis , Genetics , Phylogeny , Polymorphism, Single Nucleotide , Tuberculosis , Epidemiology , MicrobiologyABSTRACT
Objective To establish multiple‐locus variable‐number tandem repeat assay(MLVA) genotyping database for clinical isolates of methicillin‐resistant Staphylococcus aureus(MRSA) in Kunming area and analyse the prevalence status of MRSA in hos‐pital ,through establishing a classification method for MRSA by homology MLVA which was appropriate to routine application in clinical laboratory .Methods A total of 111 strains of MRSA isolated by the Clinical Microbiology Chamber of the First People′s Hospital of Kunming City from October 2010 to December 2013 were collected .The polymerase chain reaction(PCR) amplification and electrophoresis for analysis of PCR products were carried out for the seven sites of variable number tandem repeats(VNTR) , classification of strain based on genotypes was carried out ,as well .Results The sequencing results of VNTR09‐01 site showed 9 bp repetitive sequence elements whose regularity was not strong ,and the repetitive elements was mutable .The 111 isolates were divid‐ed into 25 kinds of genotypes(A -Y) ,among which genotype G ,A and B were the main types ,accounted for 47 .7% ,13 .5% and 8 .1% respectively .Conclusion MLVA could be generally applied in the seven sites of VNTR in this study .Some departments might exit concentrated epidemic of homologous MRSA strains ,which is worthy of being paid more attention .
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Aims: Staphylococcus aureus is a Gram positive pathogen distributed worldwide and represents a rising problem for both hospitals and community. The aims of the study were to examine the antibiograms, toxin profiles as well as the genetic diversity of a set of S. aureus isolates from clinical and food samples. Methodology and results: To get some insights on the genetic heterogeneity and test for the presence of certain virulence genes, all isolates were subjected to different PCR amplifications and antibiotic sensitivity analysis. The mecA gene was detected in both clinical and food isolates. Resistance to penicillin and amoxicillin was observed in both clinical and food isolates. About 88% of both food and clinical isolates harbored the toxin gene sea, while 70% and 29% of clinical and food isolates respectively, harbored sec. The seb gene was detected in 59% and 18% of clinical and food isolates, respectively. Dendrograms prepared from the VNTR, antibiograms and toxin profiles, revealed 89, 52 and 12 clusters, respectively. Thus, suggesting a very high heterogeneity among the isolates. Conclusion, significance and impact of study: Strains used in this study showed high heterogeneity when examined by VNTR or antibiograms, while appeared less heterogeneous when dendrogram was generated based on toxin profiles. This study highlights the fact that methicillin resistance in S. aureus might be generated within the health institutions or the community. Obtained results also might help health authorities understand the origin of methicillin resistant clones within the study area.
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Staphylococcus , Drug Resistance, MicrobialABSTRACT
Objective A suspected strain of Brucella canis isolated in Hebei Province in 2015 was identified and its genetic characteristics were analyzed.Methods After conventional identification of the bacteria strain,multiplex polymerase chain reaction (M-PCR) and multiple-locus variable-number tandem-repeat analysis (MLVA) were conducted to determine its species and genetic characteristics.Results The strain was identified as Brucella canis by conventional subtyping and M-PCR.Using Panel 1,the strain was genotype 3,using Panel 2A,the strain was genotype 28.It was closely clustered with Brucella canis,and differences of repeated numbers at variablenumber tandem-repeat (VNTR) loci Bruce04,Bruce07,Bruce09 and Bruce16 were also displayed.Conclusions The conventional subtyping and molecular methods can improve the stability and accuracy of the identification.Genetic characteristics of the strain is closely related to that of Brucella canis.
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Objective To explore the genetic relationship between the Chinese and the foreign species of Francisella tularensis.Methods Based on our own findings and from the literature,17 SNP,4 INDEL,and 12 VNTR were selected for phylogenetic analysis on 39 strains of F.tularensis,including 10 strains of Chinese F.tularensis and 29 strains of foreign F.tularensis that had been sequenced and published.SNP-INDEL and MLVA were used for the separation and combination.Results Data from the combined analysis indicated that 3 strains of Chinese F.tularensis with Japanese FSC022 were assigned to B5;3 strains,with Swedish FSC200 to B1;3 strains with American OSU18 to B2 and 1 strain with French FTNF002-00,German F92,and American OR96246 to B4,respectively.10 strains of Chinese F.tularensis were assigned to 4 clades and the result demonstrated a wide diversity of F.tularensis subsp.holarctica in China.Conclusion A set of simple and robust typing tools for F.tularensis subsp.holarctica were established in this study.Based on the results,F.tularensis subsp.holarctica might have had its origins in Asia.
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Objective A suspected Brucella strain, isolated from the first case of mink breeder in Hebei Province was identified and genetic characteristics were analyzed.Methods Blood sample of the patient with brucellosis was collected at brucellosis laboratory of Hebei Provincial Center for Disease Control and Prevention;anti-Brucella antibody was tested and Brucella was isolated by two phase culture bottles.Conventional methods were used to identify the isolated strain, the genetic characteristics were analyzed by multiple-locus variable-number tandem-repeat analysis (MLVA).Results Anti-Brucella antibody was tested positive.The isolated strain was identified as Brucella melitensis biovar 1 using the conventional methods.Using Pannel 1, the strain was genotype 42 clustering to the East Mediterranean Brucella Melitensis group.It was closely clustered with Brucella melitensis biovar 3, and difference of repeated numbers at variable-number tandem-repeat (VNTR) loci bruce19 was also displayed.Conclusion The case is the first brucellosis case of mink breeder in Hebei Province, the isolated strain from this patient is identified as Brucella melitensis biovar 1 and the genetic characteristics of the strain are closely related to those of Brucella melitensis biovar 3.
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Leptospirosis is the most widespread zoonosis in the world and significant efforts have been made to determine and classify pathogenic Leptospira strains. This zoonosis is maintained in nature through chronic renal infections of carrier animals, with rodents and other small mammals serving as the most important reservoirs. Additionally, domestic animals, such as livestock and dogs, are significant sources of human infection. In this study, a multiple-locus variable-number tandem repeat analysis (MLVA) was applied to genotype 22 pathogenic Leptospira strains isolated from urban and periurban rodent populations from different regions of Argentina. Three MLVA profiles were identified in strains belonging to the species Leptospira interrogans (serovars Icterohaemorrhagiae and Canicola); one profile was observed in serovar Icterohaemorrhagiae and two MLVA profiles were observed in isolates of serovars Canicola and Portlandvere. All strains belonging to Leptospira borgpetersenii serovar Castellonis exhibited the same MLVA profile. Four different genotypes were isolated from urban populations of rodents, including both mice and rats and two different genotypes were isolated from periurban populations.
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Animals , Mice , Rats , Leptospira/genetics , Rodentia/microbiology , Argentina , Didelphis/microbiology , Genotype , Genotyping Techniques/methods , Leptospira interrogans serovar canicola/genetics , Leptospira interrogans serovar icterohaemorrhagiae/genetics , Leptospira interrogans serovar pomona/genetics , Leptospira/classification , Leptospira/isolation & purification , Leptospirosis/transmission , Serogroup , Serotyping , Tandem Repeat Sequences/genetics , Urban Population , Virulence/geneticsABSTRACT
Objective To evaluate the capability of multilocus variable-number tandem-repeat ( VNTR) analysis ( MLVA) and pulsed-field gel electrophoresis ( PFGE) for genotyping Salmonella enterica serovar Typhi (S.Typhi) isolates.Methods Five polymorphic VNTRs (SAL02,SAL11,SAL16,SAL20, and TR4699 ) that were observed in S.Typhi strains from previous studies were selected to establish MLVA . Twenty-one epidemiologically unrelated S.Typhi strains that were isolated from Shenzhen ,China from 2002 to 2007 were genotyped by the established MLVA , and the results were compared with those by PFGE . Results The Simpson′s index of diversity ( D value ) for all five different VNTRs ranged from 0.838 to 0.943 .A total of 19 MLVA profiles and 19 PFGE profiles were found , respectively .The D value for both MLVA and PFGE were 0.99 and the test results from two analyses were identical .Conclusion The five polymorphic VNTRs analysis could be used as an alternative typing scheme for epidemiologic investigation of S.Typhi infection .
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Objective To evaluate the clfB typing method in discriminating the ST239 methicillin-resistant Staphylococcus aureus (MRSA) isolated from patients under nosocomial infection in Tianjin first central hospital so as to access the clinical risk factors and outcomes of the MRSA nosocomial infection from ICU and non-ICU departments.Methods Forty-two stains of MRSA with known SCCmec type were chosen in both ICU (n=35) and non-ICU (n=7) wards,from 2006 to 2012,of which MLST genotype was ST239.Clinical risk factors and rates on drug resistant to MRSA were counted,respectively.Results All the isolates of MRSA belonged to the same lineage 3 and 6 heplotypes,based on clfB variable-number random repeats typing.Thirty-five isolates from ICU belonged to 6 heplotypes,among which clfB3-52,3-52E,3-50,3-52C,3-50A and 3-50E were accouted for 42.9％,37.1％,8.6％,5.7％,2.9％ and 2.9％,respectively.Seven isolates from non-ICU belonged to 3 heplotypes,in which 3-52,3-52E and 3-50 were accouted for 42.8％,28.6％,28.6％,respectively.When clfB typing was combined with SCCmec typing in use,results showed that the index of discrimination as 0.767,better than clfB (ID=0.688) or SCCmec (ID=0.303) used alone.SCCmec Ⅲ-clfB3-52E seemed as the major clone among the 10 heplotypes of clfB/SCCmec typing,which was accounted for 40.4％.There were significant differences on the length of hospitalization (P＜0.005) and the duration of antibiotics use (P＜0.05) between ICU and non-ICU.Conclusion The clfB typing method which was based on variable-numbers of tandom repeats showed powerful ability of resolution.It could also be combined with MLST and SCCmec typing to be used in local epidemiological investigations.
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Objective To establish the standard operating procedures on multiple locus variable number tandem repeat analysis and to evaluate the values in identification of Brucella(B.) melitensis and epidemiological trace-back.Methods Sixteen B.melitensis,22 B.abortus,21 B.suis and 10 B.cnais were investigated by Brucella MLVA-16 genotyping scheme.All data were analyzed using BioNumerics version 5.1 software (AppliedMaths,Belgium).Clustering analysis was based on the categorical coefficient and unweighted pair group method using arithmetic averages(UPGMA) method.Polymorphism at each locus was quantified using Nei's diversity index.Resultant genotypes were compared using the web-based Brucella 2010 MLVA database.Results MLVA methods were successfully established and some strains can be clustered.Bruce06,bruce08,bruce11,bruce12,bruce42,bruce43,bruce45 and bruce55 were useful for species identification of Brucella isolates.Bruce04,bruce07,bruce09,bruce16 and bruce 30 afforded a higher discriminatory power for investigation of strain relatedness in regions of endemicity.Conclusions TheMLVAmethod has proved to be highly discriminatory and epidemiological concordance and is easy for Brucellosis surveillance in province-level lab.
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Objective To inspect the source of an outbreak with Mycoplasma pneumoniae (Mp).Methods We carried out real-time PCR to analyze specimens collected from pediatric patients in Beijing during January 2010 to May 2012,diagnosed as pneumonia or a respiratory infection according to clinical symptoms.These positive samples were analyzed by the M-P typing system(M:multiple-locus variable-number tandem-repeat analysis,MLVA; P:P1-restriction fragment length polymorphism analysis,P1-RFLP).Results Sixty-nine specimens were tested positive to Mp by the real-time PCR in 446 specimens from pediatric patients.The infection rate was 11.69％,15.56％ and 20.00％ respectively in 2010,2011 and the first half of 2012.According to the M-P system,11 distinct genotypes were identified from 69 positive specimens,M43562P1 and M53562P1 were the two main genotypes that showed an increasing trend from 2010 to 2011,and M33562P1 and M63562P1 showed an increasing trend from 2011 to 2012 in China.Conclusion During this international Mp epidemic,the infection rate of Mp was also increase in Beijing in 2011,and M43562P1 and M53562P1 were the two main genotypes.Among them,M43562 were consistent with pop genotypes in Europe,and M53562 were consistent with pop genotype in Israel.The M-P system would be valuable to monitor the epidemic of Mp in different countries in the world.
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Objective To determine the molecular characteristics of predominant Salmonella typhi and Salmonella paratyphi A strains prevalent in Hangzhou area from 2002 to 2008.Methods Pulse field gel electrophoresis (PFGE),multi-locus variable-number tandem repeat analysis (MLVA) and multi-locus sequence typing (MLST) were applied for typing as well as analysis of the molecular characteristics of 31 S.typhi isolates and 404 S.paratyphi A isolates from Hangzhou area during 2002 to 2008.Results The 404 S.paratyphi A isolates could be divided into six PFGE types (P1-P6).99.0％ of the S.paratyphi A isolates (400/404) belonged to the same one clone family (P1 and P2 types),in which P1 strains occupied 93.3％ (373/400) of the isolates.The 31 S.typhi isolates displayed a high diversity,which could be classified into 14 PFGE types,28 MLVA types with 90.3％ resolving power and 3 MLST types.The S.typhi strains prevalent in Hangzhou area were similar to those in Southeast Asia but different from those in Europe.The variable number tandem repeat (VNTR) sites with high polymorphism,TR1,TR2 and Sal02,could be used to the markers for diagnosis of S.typhi isolates in the area.The MLST types of 31 S.typhi isolates included all the three types currently found in the world but the ST2 type of S.typhi strains was predominant (23/31,74.2％).Conclusion The paratyphoid A prevalence in Hangzhou area in the recent years is caused by infection of the same clone family of S.paratyphi A whereas the S.typhi strains prevalent in the area display a high diversity.