Table 3.
Prevalence of virulence genes among E. coli strains isolated from different hosts and environmental sources
| Isolate group or source | % of isolates carrying the indicated virulence geneb |
|||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| aer | cnf1 | fimH | fyuA | hlyA | hra | ibeA | iha | iroN | irp2 | ompT | PAI | papC | papG_II | papG_III | sfa-foc | traT | usp | |
| Phylogenetic groupa | ||||||||||||||||||
| A | 21.1 | 0.0 | 44.7 | 2.6 | 2.6 | 13.2 | 0.0 | 15.8 | 0.0 | 42.1 | 13.2 | 2.6 | 7.9 | 10.5 | 36.8 | 2.6 | 50.0 | 0.0 |
| B1 | 1.9 | 5.6 | 83.3 | 7.4 | 2.8 | 31.5 | 2.8 | 0.0 | 6.5 | 13.9 | 45.4 | 3.7 | 7.4 | 0.0 | 6.5 | 53.7* | 53.7 | 8.3 |
| B2 | 21.7 | 33.3* | 92.8 | 43.5* | 13.0 | 43.5 | 29.0* | 21.7 | 26.1 | 98.6* | 98.6* | 84.1* | 59.4* | 27.5* | 87.0* | 29.0 | 62.3 | 87.0* |
| D | 32.0 | 4.0 | 78.0 | 10.0 | 2.0 | 34.0 | 10.0 | 18.0 | 12.0 | 30.0 | 54.0 | 12.0 | 22.0 | 8.0 | 26.0 | 16.0 | 64.0 | 16.0 |
| Unclassified | 21.1 | 0.0 | 63.2 | 0.0 | 5.3 | 10.5 | 0.0 | 5.3 | 5.3 | 10.5 | 21.1 | 0.0 | 5.3 | 5.3 | 10.5 | 10.5 | 57.9 | 5.3 |
| Host type | ||||||||||||||||||
| Human | 26.1* | 13.0 | 88.7* | 19.1 | 5.2 | 24.3 | 12.2 | 24.3* | 15.7 | 71.3* | 69.6* | 48.7* | 36.5* | 22.6* | 64.3* | 13.0 | 55.7 | 51.3* |
| Nonhuman | 8.8 | 9.4 | 70.6 | 12.9 | 5.3 | 35.3 | 8.2 | 1.8 | 8.2 | 20.0 | 42.9 | 7.6 | 12.9 | 1.2 | 12.9 | 43.5* | 58.2 | 11.2 |
| Bovines | 18.2 | 0.0 | 56.8 | 2.3 | 9.1 | 40.9 | 0.0 | 0.0 | 0.0 | 13.6 | 34.1 | 0.0 | 9.1 | 2.3 | 6.8 | 20.5 | 79.5 | 0.0 |
| Birds | 7.0 | 11.6 | 95.3 | 16.3 | 0.0 | 37.2 | 9.3 | 2.3 | 16.3 | 20.9 | 55.8 | 9.3 | 14.0 | 0.0 | 11.6 | 74.4 | 44.2 | 20.9 |
| Other nonhuman mammals | 6.1 | 22.4 | 85.7 | 28.6 | 10.2 | 42.9 | 16.3 | 4.1 | 14.3 | 32.7 | 59.2 | 18.4 | 24.5 | 2.0 | 22.4 | 67.3 | 59.2 | 20.4 |
| Dogs | 10.7 | 25.0 | 75.0 | 32.1 | 10.7 | 39.3 | 17.9 | 7.1 | 10.7 | 35.7 | 57.1 | 21.4 | 25.0 | 3.6 | 21.4 | 46.4 | 50.0 | 28.6 |
| Cats | 0.0 | 14.3 | 100.0 | 19.0 | 9.5 | 38.1 | 9.5 | 0.0 | 19.0 | 19.0 | 57.1 | 14.3 | 19.0 | 0.0 | 14.3 | 95.2 | 47.6 | 9.5 |
| Pigs | 0.0 | 11.1 | 0.0 | 11.1 | 0.0 | 22.2 | 11.1 | 0.0 | 0.0 | 11.1 | 11.1 | 0.0 | 11.1 | 0.0 | 11.1 | 0.0 | 44.4 | 0.0 |
| Water | 4.3 | 0.0 | 52.2 | 0.0 | 0.0 | 21.7 | 8.7 | 0.0 | 0.0 | 13.0 | 21.7 | 0.0 | 0.0 | 0.0 | 13.0 | 0.0 | 69.6 | 0.0 |
The number of E. coli isolates corresponding to each phylogenetic group and host type is consistent with Table 2.
Virulence genes in each strain were detected by PCR using well-defined primer sets (Table 1). Numbers listed represent the percentage of isolates that carry the designated allele: aer, aerobactin; cnf1, cytotoxic necrotizing factor 1; fimH, d-mannose-specific adhesin; fyuA, ferric yersiniabactin receptor; hlyA, α-hemolysin; hra, heat-resistant agglutinin; ibeA, invasion of brain endothelium; iha, fimbriae or adhesin; iroN, novel catecholate siderophore receptor; irp2, yersiniabactin biosynthesis pathway; ompT, outer membrane endoprotease, PAI (malX), pathogenicity-associated island marker; papC, pilus assembly, central region of pap operon; papG, Gal(α1-4)Gal-specific pilus tip adhesin molecule; papGII, pyelonephritis-associated; papGIII; cystitis-associated; sfa-foc, central region of sfa (S fimbriae) and foc (F1C fimbriae) operons; traT, surface exclusion, serum survival (outer membrane protein); usp, uropathogenic-specific protein (bacteriocin). Statistical significance (*) for each gene was determined using a Chi-square test for heterogeneity or independence comparing all groups, followed by Fisher exact tests between two chosen groups: for phylogenetic groups, comparisons were made between group B2 and the group (usually D) with the next highest rate of prevalence for that particular gene; for host type, comparisons were made between the group of human isolates and the group of nonhuman isolates.