ABSTRACT
<p><b>OBJECTIVE</b>To understand the epidemiologic and etiologic characteristics of diarrheagenic Escherichia (E.) coli infections in Shenzhen.</p><p><b>METHODS</b>Stool samples were collected from acute diarrheal patients in four sentinel hospitals in Shenzhen and diarrheagenic E. coli strains were isolated and identified with multiplex real-time PCR. Serotyping and pulsed-field gel electrophoresis (PFGE) typing were conducted for the diarrheagenic E. coli isolates.</p><p><b>RESULTS</b>A total of 74 diarrheagenic E. coli strains were isolated from 1 823 stool samples (4.06%). The patients were mainly young children aged <3 years and adults aged 20-39 years, and the infections mainly occurred during May-September of a year. Enterotoxigenic E. coli (ETEC) and enteropathognic E. coli (EPEC) were predominant (45.9% and 31.1%). Serogroups and PFGE patterns varied among the diarrheagenic E. coli isolates. However, serogroup O159 were predominant in ETEC and there were 5 clusters with ≥2 strains sharing same PFGE patterns.</p><p><b>CONCLUSIONS</b>ETEC and EPEC were predominant in diarrheagenic E. coli strains isolated from diarrheal patients in Shenzhen. Age and season specific characteristics of diarrheagenic E. coli infections were observed. The serotypes and PFGE patterns of diarrheagenic E. coli strains varied. Close attention should be paid to the possible ETEC outbreak.</p>
Subject(s)
Adult , Child, Preschool , Humans , Young Adult , China , Epidemiology , Diarrhea , Epidemiology , Microbiology , Disease Outbreaks , Electrophoresis, Gel, Pulsed-Field , Enterotoxigenic Escherichia coli , Classification , Escherichia coli Infections , Epidemiology , Real-Time Polymerase Chain Reaction , SerotypingABSTRACT
Objective To establish a molecular typing system of Staphylococcus aureus by using resolution melting for food-poi-soning fast tracing.Methods Primers were designed and synthesized according to the literature of VNTR in Staphylococcus au-reus ,and were used to perform molecular typing on the strains which had detected by PFGE,then 4 types of VNTRs were with higher discriminatory power were selected.On this basis,we established a molecular typing system for the detection of 59 Staphy-lococcus aureus isolated from food poisoning.Results The molecular typing system has good precision for detection.The standard deviation(s)of within-batch repetitive experiments were 0.03 -0.05 ℃,between-batch repetitive experiments were 0.04 -0.06℃,between-day repetitive experiments were 0.04-0.06 ℃.At the same time,the 59 strains of Staphylococcus aureus were divided into 19 types which were 11 epidemic clones and 8 sporadic clones.The correlation coefficient of Simpson was 0.916 4.Conclusion The molecular typing system for Staphylococcus aureus based on resolution melting was simple,fast and repeatable.It can be ap-plied to fast tracing and screen of Staphylococcus aureus in food poisoning.
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Objective To analyze the etiological characteristics,virulence genes and plasmids that carrying diarrhea-causing Proteus mirabilis and to assess their relationship with drug resistance and pathogenicity. Methods Proteus mirabilis coming from six different sources (food poisoning,external environment and healthy people) were analyzed biochemically,on related susceptibility and pulsed-field gel electrophoresis (PFGE). Virulence genes were detected by PCR. Plasmids were extracted and sequenced after gel electrophoresis purification. Results The biochemical characteristics of Proteus mirabilis from different sources seemed basically the same,and each of them showed having common virulence genes,as ureC,rsmA,hpmA and zapA. However,the PFGE patterns and susceptibility of these strains were different,so as the plasmids that they carried. Plasmid that presented in the sequenced strain showed that the 2 683 bp length plasmid encodes qnrD gene was associated with the quinolone resistance. Conclusion Etiological characteristics and molecular characteristics of Proteus mirabilis gathered from different sources,were analyzed. Results indicated that traditional biochemical analysis and common virulence gene identification might be able to distinguish the strains with different sources. However,PFGE and plasmids analysis could distinguish the sources of strains and to identify those plasmids that commonly carried by the drug-resistant strains. These findings also provided theoretical basis for further study on the nature of resistance and pathogenicity in Proteus mirabilis.
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Objective To analyze the etiological characteristics,virulence genes and plasmids that carrying diarrhea-causing Proteus mirabilis and to assess their relationship with drug resistance and pathogenicity. Methods Proteus mirabilis coming from six different sources (food poisoning,external environment and healthy people) were analyzed biochemically,on related susceptibility and pulsed-field gel electrophoresis (PFGE). Virulence genes were detected by PCR. Plasmids were extracted and sequenced after gel electrophoresis purification. Results The biochemical characteristics of Proteus mirabilis from different sources seemed basically the same,and each of them showed having common virulence genes,as ureC,rsmA,hpmA and zapA. However,the PFGE patterns and susceptibility of these strains were different,so as the plasmids that they carried. Plasmid that presented in the sequenced strain showed that the 2 683 bp length plasmid encodes qnrD gene was associated with the quinolone resistance. Conclusion Etiological characteristics and molecular characteristics of Proteus mirabilis gathered from different sources,were analyzed. Results indicated that traditional biochemical analysis and common virulence gene identification might be able to distinguish the strains with different sources. However,PFGE and plasmids analysis could distinguish the sources of strains and to identify those plasmids that commonly carried by the drug-resistant strains. These findings also provided theoretical basis for further study on the nature of resistance and pathogenicity in Proteus mirabilis.
ABSTRACT
<p><b>OBJECTIVE</b>To analyze the etiological characteristics, virulence genes and plasmids that carrying diarrhea-causing Proteus mirabilis and to assess their relationship with drug resistance and pathogenicity.</p><p><b>METHODS</b>Proteus mirabilis coming from six different sources (food poisoning, external environment and healthy people) were analyzed biochemically, on related susceptibility and pulsed-field gel electrophoresis (PFGE). Virulence genes were detected by PCR. Plasmids were extracted and sequenced after gel electrophoresis purification.</p><p><b>RESULTS</b>The biochemical characteristics of Proteus mirabilis from different sources seemed basically the same, and each of them showed having common virulence genes, as ureC, rsmA, hpmA and zapA. However, the PFGE patterns and susceptibility of these strains were different, so as the plasmids that they carried. Plasmid that presented in the sequenced strain showed that the 2 683 bp length plasmid encodes qnrD gene was associated with the quinolone resistance.</p><p><b>CONCLUSION</b>Etiological characteristics and molecular characteristics of Proteus mirabilis gathered from different sources, were analyzed. Results indicated that traditional biochemical analysis and common virulence gene identification might be able to distinguish the strains with different sources. However, PFGE and plasmids analysis could distinguish the sources of strains and to identify those plasmids that commonly carried by the drug-resistant strains. These findings also provided theoretical basis for further study on the nature of resistance and pathogenicity in Proteus mirabilis.</p>