Phylogenetic relationships, virulence factors and Rep-PCR epidemiological analysis of E. coli from human sources

Abstract

The potential of Escherichia coli to cause of extra-intestinal infections was studied on a group of 94 clinical isolates. In this work, 32 E. coli isolates from urinary tract infections, 25 from bacteraemia, 12 from low respiratory tract infections, and 25 from the normal commensal flora were characterized for the phylogenetic type, the virulence factors (VFs) carriage and the Rep-PCR clonal composition.The B2 phylogenetic type was predominant among the urinary isolates (59%), the B2 and D strains among the haematic isolates (32% and 32%).The A phylogenetic type was predominant among the commensal and the respiratory isolates (52% and 58% respectively).The distribution of the B2 type strains among the urinary isolates and of the D type strains among the faecal isolates was suggesting a urinary-origin for the B2 phylogenetic type isolates found in the blood and a direct faecal derivation for the haematic isolates with D phylogenetic type.Twenty-nine VFs were analyzed.The B2 and D type strains carried a higher burden of VFs than the A and B1 phylogenetic type strains (average of VFs/strain = 8 vs 3). Some of the VFs were homogeneously distributed among the phylogenetic types (fimH, iutA, fyuA, traT). The PAI, papGII, ibeA, KpsMTIII were exclusive of B2 and D phylogenetic type strains, while sfa/foc, focG, cnf1, hlyA and rfc were exclusively observed among the B2 type strains.The clustering analysis by Rep-PCR distinguished two groups of strains, the first including 96.77% of B2 and D type strains, while the second encompassing 91,5% of A and B1 type strains.