Correlation between pulsed-field gel electrophoresis profiles and Salmonella serotypes / 中华流行病学杂志

Objective To analyze the relationship between pulsed-field gel electrophoresis (PFGE) subtyping and serotyping of Salmonella (S.).Methods PFGE was performed and profiles were analyzed on 1230 Salmonella isolates which comprising the top five serotypes including Typhimurium,Enteritidis,Derby,Agona and Senftenberg identified in China.The potential predictive relationship between PFGE banding patterns and particular serotypes was compared and the discriminatory consensus band class markers of individual serotypes were identified.Results Among all the 1230 Salmonella strains,1149 strains were found assistant with serotyping through PFGE cluster analysis,providing the matching accuracy reaching 93.4％.For the five serotypes,the positive prediction rate appeared more than 90.0％ and the negative prediction rate was over 95.0％ on serotype cluster prediction.Conclusion Results presented in this study were representatives of the top 5 Salmonella serovars,showing that PFGE cluster analysis could provide clues to identity and confirmation of serotypes.

Molecular analysis on non-O1 and non-O139 Vibrio cholerae isolates / 中华流行病学杂志

Objective According to results from the two-month consecutive surveillance program in Maanshan,six suspected cases of non-O1 non-O139 Vibrio (V.) cholerae infection,were found that called for identification of pathogens as well as molecular-epidemiological analysis to determine the aggregation of the epidemic situation.Methods Biochemical and serotype identification,hemolysis test,and drug sensitive test were used to detect the drug resistance spectrum.Real-time PCR and conventional PCR were used to detect the presence of V.cholerae specific genes,virulent genes and its related genes,including ompW,ctx,tcpA,toxR,hlyA,zot,ace,rstR and g ⅢCTX.Pulsed-field gel electrophoresis (PFGE) was used to analyze the molecular type of strains.Results All the six isolates of non-O 1 non-O 139 V.cholerae were identified by biochemical and serologic tests,and appeared to be β hemolytic.Twelve out of the 14 kinds of drugs showed 100％ sensitive.All isolates were positive of ompW gene by real-time PCR,but negative for ctx,tcpA,zot,ace,rstR and gⅢ CTK.Five of the six isolates were positive for toxR and hlyA,except for strain 1001434446.All strains had different PFGE types,but two strains had similar types.All strains had a low similarity compared to the toxigenic V.cholerae.Conclusion Six cases ofnon-O1 and non-O139 nontoxigenic V.cholerae infection appeared in the same period.Along with epide(m)iological information,we noticed that these cases had a sporadic nature,but frequently appeared in the same area.We got the impression that public health measurements should be strengthened,with special attention paid to those diarrhea outbreaks caused by non-O 1 /non-O 139 strains since V.cholerae had appeared in low incidence.

Molecular subtyping of Vibrio cholerae isolates from outbreaks of cholera by pulsed-field gel electrophoresis in Hainan in 2008 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To analyze the molecular characteristics and genetic correlations of Vibrio cholerae isolates in Hainan in 2008, so as to provide pathogenic proof to diagnose the plague.</p><p><b>METHODS</b>Seventy six cholera strains were isolated from this cholera epidemic.69 strains were obtained from patients, 7 were isolated from external environment, among which, one was from patient's toilet, one from water sample, three were isolated from fish pond near patient's home, one came from swab of the patient vomit on the ground of health center and one from swab of kitchen knife from Hainan University canteen respectively. With conventional aetiological methods, pulse-field gel electrophoresis was conducted and the patterns of the 76 isolates were analyzed. The PFGE image was analyzed using BioNumerics (Version4.0, Applied Maths BVBA, Belium). Image bands were identified and similarity coefficient was automatically generated.</p><p><b>RESULTS</b>Seventy six strains were isolated from Vibrio cholerae outbreaks in Hainan in 2008.5 PFGE patterns of patient's isolates in June were the same, sharing a similarity coefficient of 100%. 70 PFGE patterns of patients and water in October and November were completely same, the similarity coefficient being 100%. But they were not same as that of June. 1 PFGE pattern of isolate from the sample in Hainan University was different, only sharing a similarity coefficient of 79.7%, which showed no correlation with the outbreak.</p><p><b>CONCLUSION</b>Different outbreaks of Vibrio cholera occurred in Hainan in 2008. The epidemic in October and November at different counties was one outbreak. The pollution of water in environment was an important factor for outbreak.</p>

Study on the epidemiological characteristics and molecular typing of Salmonella enterica subsp. enterica serovar Senftenberg in Shanghai / 中华流行病学杂志

ation were complicated, with the characteristics as the obvious decreasing number of patients, with no food-borne isolates in 2007.

Molecular characterization of Vibrio cholerae phage-type 6b epidemic isolates from 1998 to 2001 in Sichuan province / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate the molecular characteristics of phage-type 6b isolates emerging in 1998-2001 cholera epidemics in Sichuan province.</p><p><b>METHODS</b>Isolates were analyzed by phage-typing, pulsed field gel electrophoresis (PFGE) and ompW gene sequencing.</p><p><b>RESULTS</b>All phage-type 1b and 6b isolates in Sichuan province from 1998 to 2001 were toxigenic. A total of 24 patterns were identified after PFGE analysis, and one predominant pattern consisted of 13 isolates. Several 1b and 6b isolates from Sichuan and isolates of the 1b from other provinces showed the same PFGE pattern. Mutation in ompW gene was found in 6b isolates.</p><p><b>CONCLUSION</b>V.cholerae O1 6b isolates in Sichuan province from 1998 to 2001 have special genetic markers, and might genetically correlate with contemporaneous 1b isolates.</p>

Study on the application of pulsed-field gel electrophoresis regarding infection sources identification during an outbreak of Vibrio cholerae in Jiangxi Province / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the correlation between Vibrio cholerae strains isolated from natural enviroment and fishery products and the source of infection during V. cholerae outbreaks.</p><p><b>METHODS</b>Cholera toxin gene was detected by polymerase chain reaction (PCR) amplification. Pulsed-field gel electrophoresis (PFGE) was used to subtype the isolates. Results of PFGE were analyzed and clustered by BioNumerics software (Version 4.0).</p><p><b>RESULTS</b>During the outbreaks, a total number of thirty O139 V. cholerae related serogroups were collected from patients, carriers, sewage and fishery products were identified and proved to be toxigenic. They could be clustered into four PFGE patterns when digested by Not I. These two V. cholerae outbreaks were caused by the same source of infection because of the following reasons: (1) PFGE patterns of the predominant strains isolated from two outbreaks were identical; (2) they were identical to the PFGE patterns of the strains isolated from the green turtle and rana catesbiana which were bought from the same wholesale store.</p><p><b>CONCLUSION</b>Green turtle and rana catesbiana that were contaminated by toxigenic O139 V. cholerae strains seemed to be the source of infection causing the O139 V. cholerae outbreaks in Jiangxi province. Rapid laboratory surveillance and epidemiologic investigation were important in identifying the source of infection during the outbreaks of V. cholera.</p>

Establishment of fluorescent amplified fragment length polymorphism in Vibrio cholerae and evaluation in molecular typing / 中华流行病学杂志

<p><b>OBJECTIVE</b>To develop fluorescent amplified fragment length polymorphism (AFLP) method and to evaluate the its typing capability with pulsed-field gel electrophoresis (PFGE) in molecular typing of Vibrio cholerae.</p><p><b>METHODS</b>Forty-seven strains of V. cholerae, with different PFGE patterns, were selected as the reference group to optimize the selective primers of AFLP analysis. Eighty-three strains including 20 strains from one epidemic episode, isolated from different provinces during 1961 and 2005, were used to compare the typing abilities of AFLP and PFGE. LI-COR4300 DNA sequencing system was used for AFLP electrophoresis. The images were recorded by Saga(MX) software and transferred to BioNumerics for clustering analysis. A standard protocol for V. cholerae from PulseNet was used in PFGE.</p><p><b>RESULTS</b>When comparison was made with different selective primers on AFLP based on the 47 strains, results showed that the optimized selective primer pair was EcoR I-G/Mse I-T, and the reproducibility of the tests was 99.2%. Eighty-three isolates showed 52 AFLP patterns and 44 PFGE patterns, with D values as 0.9545 (AFLP) and 0.9251 (PFGE) respectively.</p><p><b>CONCLUSION</b>The protocol of fluorescent AFLP on V. cholerae typing was established. AFLP was higher than PFGE in discrimination of V. cholerae which could be used for molecular typing. When combined with PFGE, AFLP became a more insightful tool to identify genome difference of different isolates.</p>

Molecular typing of Neisseria meningitidis serogroup C strains with pulsed field gel electrophoresis in China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the characteristics of epidemiology and molecular typing on Neisseria meningitidis serogroup C strains associated with outbreaks of Anhui province and sporadic cases in China, using pulsed field gel electrophoresis (PFGE).</p><p><b>METHODS</b>212 Neisseria meningitidis serogroup C strains were isolated from invasive meningococcal cases, close contacts and healthy carriers, including 48 strains from Anhui province with 38 strains associated with serogroup C outbreaks. PFGE were performed by genomic DNA digestion with Nhe I restriction enzyme. The results of PFGE were analyzed by BioNumerics software (Version 4.0, Applied Maths BVBA, Belgium).</p><p><b>RESULTS</b>A total number of 212 Neisseria meningitidis serogroup C isolates were typed by 43 patterns, named AH1 to AH43. In China, AH1 pattern was the major PFGE pattern with 69.3% (n = 147) of all strains, distributed in 11 provinces. Three types of PFGE patterns (AH1 to AH3) were found in 48 strains from Anhui province, in which, 93.8% (n = 45) belonged to AH1. 97.4% (n = 37) of 38 strains associated with serogroup C outbreaks in Anhui province showed AH1 pattern. A total of 53 serogroup C strains were isolated from invasive meningococcal cases with 67.9% (36/53) of AH pattern. 71.9% (87/121) of serogroup C strains isolated from contacts of invasive meningococcal cases was AH1 pattern and 63.2% (24/38) of the strains from healthy carriers showed AH1 pattern.</p><p><b>CONCLUSION</b>By PFGE typing and analysis, AH1 pattern of Neisseria meningitidis serogroup C strains was proved to be the main clone which causing the outbreaks in Anhui province and might be responsible for the sporadic serogroup C meningococcal disease epidemics else where in the country.</p>