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Objective To measure the transcription level of thermostable direct hemolysin gene (TDH)in 24 strains of Vibrio parahaemolyticus.Methods Total RNA was extracted from strains of Vibrio parahaemolyticus which were isolated from patients,seafood and environment.The RNA was proved TDH positive with routine PCR method;then the real -time fluorescent quantitative PCR was carried out to obtain the cycle of threshold (Ct)of THD and internal standard of 16s rRNA.Transcription level of THD compared with 16s rRNA was designated as ΔCt which was calculated as Ct value of THD minus Ct value of 16s rRNA.Results Ct values of THD,16s rRNA and the difference between them of the 24 strains was 18.04 ~25.95,8.30 ~10.93 and 8.28 ~15.34 respectively.The difference between the maximum and the minimum of ΔCt was 7.06;the highest transcription level was 133 (ΔΔCt =27.06 )times of the lowest one.Conclusion A great difference of transcription level of THD in Vibrio parahaemolyticus has been proved and further study is needed to clarify the possible molecular mechanisms and relationship between the transcription level of THD and pathogenic mechanism.
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Objective To study the epidemiological and etiological characteristics of typhoid and paratyphoid fever in high epidemic areas. Methods Reported data on typhoid and paratyphoid fever during 1988- 2007 in Ningbo were analyzed epidemiologically. Shellfish from the market was collected for laboratory testing and ,Salmonella typhi strains collected from the patients were also studied. Results Number of reported cases on both typhoid and paratyphoid fever was 19 404 with 7 deaths, from 1988 to 2007. The annual mean incidence was 17.68 per one hundred thousand with the fatality rate as 0.36 per thousand. Most cases were among adults aged 20-50 years and an obvious regional distribution was observed with high incidence seen in winter and spring. Since 1990s, the advantage strain had changed from Salmonella typhi to Salmonella paratyphi A. Etiologic studies showed that raw Anadara subcrenata and oyster were the main risk factors. One Salmonella paratyphi A strain was detected in both Anadara subcrenata and oysters collected from the market, which contained TEM-1 drug resistance gene. PFGE genotyping showed that PFGE-X2 was the strain which causing pandemic in Ningbo. Conclusion Eating contaminated raw shellfish like oysters and hairy clams was the primary risk factor, responsible for the outbreaks. Salmonella paratyphi A was the advantages pandemic strain in Ningbo. Strategies as supervision on personal hygiene and health education should be strengthened.
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<p><b>OBJECTIVE</b>To investigate the resistance genes and antibiotic resistance patterns against beta-lactams in Pseudomonas aeruginosa prevalent in burn ward.</p><p><b>METHODS</b>K-B method was performed to test bacterial resistance patterns against 9 species of beta-lactams in Pseudomonas aeruginosa isolated from wounds and dressings of the patient in burn wards. Seven species of resistance genes against beta-lactams were detected with PCR. Tazobactam-inhibited piperacillin resistance test was performed to study whether the above strains produce extended spectrum beta-lactams.</p><p><b>RESULTS</b>All 12 strains of bacteria with resistance genes detected were resistant to penicillin and cephalosporins (100%), among them 11 were resistant to all antibiotics. Tazobactam-inhibited piperacillin resistance test demonstrated that all strains with resistance genes were ESBLs.</p><p><b>CONCLUSION</b>High incidence of beta-lactams resistance genes is found in Pseudomonas aeruginosa isolated from burn ward, and they have close relationship with the occurrence of multiple drug-resistance.</p>
Subject(s)
Humans , Burn Units , Burns , Microbiology , Genes, Bacterial , Pseudomonas aeruginosa , Genetics , beta-Lactam Resistance , GeneticsABSTRACT
Objective To study the structure of class 1 integrons in 90 strains of Pseudomonas aeruginosa isolated during two periods of 1992-1996 and 2003-2005,and to get information about the structure changing of class 1 integrons by comparing their structures in two different periods.Methods Routine PCR and long PCR were performed to amplify the class 1 integrons and the gene cassettes they carried, followed with sequencing and blast via GenBank.Results Thirteen out of 41 strians ioslated during the period of 1992-1996 were positive on class 1 intergrons.Long PCR showed that the class 1 integron was 1868 bp in length and contained 2 resistance genes averagely.Six types of resistance genes of qacEA1 (n=6), sull (n=14),aadA1 (n=2),aadB (n=1),PSE-1 (n=2) and tetA (n=1) were found in these integrons, which consisted of 5 patterns of resistance cassette arrangements.Nineteen strains were proved to carry class 1 integrons in 49 isolates from 2003-2005.The mean DNA sequence length of them was 3383 bp with 3.6 resistant genes in averagely,10 types of resistance genes,qacEA1 (n=18),sull (n=25),aadA1 (n=6), aadB (n=7),aacA4 (n=2),PSE-1 (n=3),VEB-1 (n=4),OXA10 (n=1),cm1 A (n=1) and tetA (n =2),were identified in these integrons,which were composed of 9 patterns of resistance cassette arrangements.Conclusion In terms of produce length and resistance cassettes carried in the integrons, greater complexity is found in the structure of class 1 integrons in strains isolated during 2003-2005 than those during 1992-1996.