| Summary: | 碩士 === 國立中興大學 === 食品科學系 === 94 === Escherichia coli is one of the most common pathogenic bacteria which may cause infection in humans and different animal species world-wide. E. coli isolates from humans (n=110) and swine (n=61) were collected between July 2000 and January 2003 in southern Taiwan. These isolates were characterized for virulence genes, antimicrobial resistance patterns and class 1 integrons. In addition, the distributions of antimicrobial resistance genes, their integron profiles, and phylogenetic groups were investigation. The identification of virulence genes in E. coli isolates will help to identify new targets for therapy and helpful in identifying E. coli isolates pathotypes and hence aid epidemiology.
Various virulence profiles were found in our E. coli isolates from humans and swine. Similar antimicrobial resistance patterns could be observed in our animal and human isolates. All isolates were multidrug resistant and demonstrated high resistance to β-lactams, aminoglycosides, tetracyclines, sulfonamides, fluoroquinolones, spectinomycin and chloramphenicol. Results also revealed that class 1 integrons were widely present in E. coli isolates, and all class 1 integrons in this study were located on conjugated plasmids. The acquisition of new genes following horizontal gene transfer by transformation, transduction or conjugation, results in the generation of new variants of pathogens. The presence of such transferable elements implies the possibility for transmission of virulence genes to other cohabiting strains. Recombination within virulence factor genes also implies the potential for reintroduction of mobile genetic elements which contain virulence factors into preexisted established pathogens to increase the genetic diversity. Suck facts may lead E. coli to generate to generate new pathogenic variants that can escape from fail host protective mechanisms and result in new disease syndromes.
Pulsed-field gel electrophoresis (PFGE), enterobacterial repetitive PCR intergenic consensus sequences-based PCR (ERIC-PCR) and repetitive sequence-based PCR (rep-PCR) methods generated almost a unique profile for each strain. Results of this work have demonstrated genetic variability within the E. coli strains isolated from humans and swine. In addition, PFGE, ERIC and REP-PCR are rapid and reliable typing methods for E. coli. All three methods showed good discriminative ability and might be used as rapid means for comparing E. coli strains for epidemiological investigation.
E. coli subspecies revealed various genetic characteristics, including various virulence factors. Such facts lead to the different in laboratory to difficulty the complication virulence factors in E. coli strains especially when large numbers of strains are to be assayed. With the regard, microarray has become an important technology for detection of mass genes. In this report, we attempted to develop a microarray for detection different virulence genes of E. coli. PCR products of 40 virulence genes were spotted on the slide and the results showed that all tested strains could be correctly identified by our microarray. Through the use of this microarray, the pathotypes of E. coli determined.
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