Incidence of virulence factors in uropathogenic escherichia coli in two Lebanese hospitals and the evaluation of the CPS ID3 chromogenic medium for urine cultures. (c2007)

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dc.contributor.author Lahham, Majd
dc.date.accessioned 2011-10-25T11:59:51Z
dc.date.available 2011-10-25T11:59:51Z
dc.date.copyright 2007 en_US
dc.date.issued 2011-10-25
dc.date.submitted 2007-09-17
dc.identifier.uri http://hdl.handle.net/10725/899
dc.description Bibliography: leaves 50-63. en_US
dc.description.abstract Urinary tract infections are among the most frequent encountered infections. The vast majority of urinary tract infections are caused by Escberichia coli. The invasion and colonization of the urinary tract by uropathogenic E coli is mediated by its virulence factors. In this study, 160 uropathogenic E coli strains were screened for pilus associated with pyelonephritis (pap), S fimbriae (r/a), afunbriae (qfa), aerobactin (ae!), hemolysin (My), and cytotoxic necrotizing factor 1 (cnf1). The prevalence of these genes al110ng the studied isolates were 33.6, 33.1, 8.8, 45.6, 32.5, and 18.1% for pap, sfa, afa, aer, hly, and cnf, respectively. Genes coding for adherence factors were present in 81 % of the isolates confirming their importance role in tissue targeting and colonization of mucosal sites. Cnf gene was limited to hemolytic strains and was linked in most isolates to adhesins, while sfa was always associated with other virulence factors. Different combinations of genes were detected indicating possible synergisn1 and/ or the fact that the genes coding for these virulence factors are located on the bacterial chromosome. Detection of the virulence factors would be of a great value in understanding pathogenesis. CPS ID3 chromogenic medium was compared to routine media for d1e isolation, and to API system for d1e identification of urinary tract pathogens. Positive predictive values were 100% for all species included in this study except Enterococcus spp. that was 66.7%. False negative results were observe in E. coil and Enterococcus spp. isolates (96% and 92.3% respectively) indicating that additional tests should be performed, particularly when white colonies are recovered. All organisms isolated from urine samples grew on this medium, but not all could be identified based on d1e motphological characteristics of their colonies. However, using this medium had the additional benefit of reducing the time needed for urine analysis when compared to the time needed wid1 routine analysis. The most important advantage attributed to the use of CPS ID3 was d1e prompt identification of E. coil within 24 hours with no need to use additional biochenucal tests. On the other hand, being expensive, having a short shelf life and not covering Staphylococcus saprophyticus were the only important drawbacks of this medium. CPS ID3 enables presumptive identification of a high proportion of urinary tract pathogens through the color of the colony, and even pathogens that were colorless were successfully isolated using this medium. The results of the present study suggest d1at use of chromogenic medium offers a time saving med10d for d1e reliable detection and presumptive identification of urinary tract pad1ogens. Moreover, it also revealed d1at d1e studying of bacterial virulence determinants is an important aspect for the development of strategies to combat urinary tract infection. en_US
dc.language.iso en en_US
dc.subject Escherichia coli en_US
dc.subject Escherichia coli infections en_US
dc.subject Urinary tract infections en_US
dc.subject Pili (Microbiology) en_US
dc.title Incidence of virulence factors in uropathogenic escherichia coli in two Lebanese hospitals and the evaluation of the CPS ID3 chromogenic medium for urine cultures. (c2007) en_US
dc.type Thesis en_US
dc.term.submitted Summer II en_US
dc.author.degree MS in Molecular Biology en_US
dc.author.school Arts and Sciences en_US
dc.author.idnumber 200401073 en_US
dc.author.commembers Dr. Ziad Daoud
dc.author.commembers Dr. Roy Khalaf
dc.author.woa OA en_US
dc.description.physdesc 1 bound copy: vii, 63 leaves; ill.; 30 cm. Available at RNL. en_US
dc.author.division Biology en_US
dc.author.advisor Dr. Sima Tokajian
dc.identifier.doi https://doi.org/10.26756/th.2007.35 en_US
dc.publisher.institution Lebanese American University en_US

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