P fimbriae and aerobactin as intestinal colonization factors for Escherichia coli in Pakistani infants

The carriage rate of a range of virulence genes was compared between reside nt and transient Escherichia coli strains obtained from the rectal flora of 22 home-delivered Pakistani infants 0-6 months old. Genes for the followin g virulence factors were assessed using multiplex PCR: P, type 1 and S fimb riae, three P fimbrial adhesin varieties, Dr haemagglutinin, K1 and K5 caps ule, haemolysin and aerobactin. The E. coli strains examined here differed from those previously obtained from hosts in Western Europe in a lower prev alence of genes for P, S and type 1 fimbriae, K1 capsule and haemolysin. Ne vertheless, genes for P fimbriae, the class II Variety of papG adhesin, and aerobactin were significantly more common among resident than transient st rains, as previously observed in a Swedish study. The results suggest that P fimbriae and aerobactin, previously implicated as virulence factors for u rinary tract infection, might contribute to persistence of E. coli in the n ormal intestinal microflora.