ABSTRACT
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.
ABSTRACT
Objective To identify the isolates of Shewanella spp.from specimens of food poisoning based on biological and biochemical analysis.Methods Strains were obtained from the investigation on two food poisoning episodes in September and October,2007 in Ma'anshan city,Anhui province.In accordance with the national standard protocol(GB/T 4789),all specimens were enriched and isolated on selective medium,and the suspected strains were ldentified by the VITEK-32 and API20E systems.For Shewanella spp.identified by the biochemical system,more characteristics were analyzed using auxiliary biochemical,growth,hemolytic and drug-resistance tests.DNAs of Shewanella spp.were extracted,16S rDNA was PCR amplified and sequenced with universal 16S rDNA primers.Phylogenetic tree was constructed with MEGA 4.0.Results After enrichment, all specimens were inoculated to selective medium and Shewanella spp.strains were isolated from 8 samples with single colony on both TCBS and BP media.The characteristics of growth in the Triple Sugar Iron (TSI) agar appeared to have had hydrogen sulfide production but no gas production or positive oxidase.No Shewanella spp.strain was detected in WS,SS and EMB media.The 8 strains were identified as Shewanella algae(S.algae) or Shewanella putrefaciens(S.putrefaciens) by VITEK-32,as S.putrefaciens by API20E system.No other enteropathogenic bacteria,including Vibrio cholerae,Salmonella,Vibrio parahaemolyticus,Proteus vulgaris or Staphylococcus aureua,were detected from those 8 samples.From 16S rDNA phylogenetic trees,7 out of 8 ShewaneUa spp.were identified as S.algae.1 as S.putrefaeiens.Conclusion Strains of Shewanella spp.were lsolated from samples of the food poisoning episodes,providing a possible clue to investigate the role of Shewanella spp.on food poisoning