Virulence genes and pathogenicity islands in an extended-spectrum b-lactamase producing Escherichia coli strain collection from Slovenia

Abstract number: 1733_68

Zerjavic K., Orazem T., Grabnar M., Ambrozic Avgustin J.

Urinary tract infections (UTIs) belong to most common infectious diseases, being mainly caused by uropathogenic Escherichia coli (UPEC). UPEC strains possess several virulence factors (VFs), including capsules, invasins, siderophores, toxins, proteases, and various types of adhesins, that are involved in UTI pathogenesis. Some of these VFs are encoded by specific regions of bacterial chromosome, called pathogenicity islands (PAIs). Recent data revealed that quinolone resistance is often associated with extended-spectrum b-lactamase (ESBL) producing E. coli strains, which mainly belong to the non-B2 phylogenetic group and that quinolone resistant strains have fewer VFs than their quinolone-susceptible counterparts. The aim of this study was to elucidate the relationship between E. coli phylogenetic groups, virulence determinants, ciprofloxacin resistance and ESBL production in E. coli strains collected between the years 2000 and 2005 at the Institute of public health in Ljubljana. 27 strains from various sources were studied. Twelve of them were ciprofloxacin-susceptible whereas fifteen were ciprofloxacin resistant according to the CLSI guidelines. The phylogenetic group and the prevalence of twenty-four virulence factor genes and gene markers for six PAIs were determined by PCR amplification. Fifteen strains were assigned to phylogenetic group D, five to group B1, four to group B2 and three to group A. Gene markers for PAI I536 and PAI III536 were not detected. Genes associated with PAI II536, PAI IV536, PAI IIJ96 and PAI ICFT073 were detected in 11, 33, 4 and 15 percent of the strains, respectively. The most prevalent virulence genes (occurrence between 37 and 78%) were sfa, iroN, iucD, papG, kpsM, iha, iss and usp. Outstanding was the high prevalence of the picU gene (100%) and the VFs associated with E. coli translocation across the blood-brain barrier i.e. ibeA (41%) and and asl (67%) among ciprofloxacin resistant strains, while some VFs, i.e. papGII, afa, hlyA, cnfI and vat, were found exclusively among ciprofloxacin susceptible strains. Our results are generally in accordance with previous reports and indicate a distribution of UTI strains in two groups i.e. highly virulent and low resistant, and low virulent and highly resistant, thus raising at least two questions: (i) what are the mechanisms that allow strains from the first group to survive and (ii) which VFs do strains from the second group use to cause an infection.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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