TABLE 3.
Distribution of virulence-associated genes among the A, B1, B2, and D phylogroups (618 studied Escherichia coli isolates).
| Virulence gene |
Number (%) of isolates |
Total | p-value2 | |||
|
Phylogroup A |
Phylogroup B1 |
Phylogroup B2 |
Phylogroup D |
|||
| 35 (5.7) | 53 (8.6) | 492 (79.6) | 38 (6.1) | 618 (100) | ||
| papA | 13 (37.1) | 6 (11.3) | 306 (62.2)1 | 4 (10.5) | 329 (53.2) | <2.2E-16 |
| kpsMTII | 4 (11.4) | 2 (3.8) | 307 (62.4) | 24 (63.2) | 337 (54.5) | 1.31E-23 |
| sfaS | 0 (0.0) | 0 (0.0) | 79 (16.1) | 0 (0.0) | 79 (12.8) | 1.19E-06 |
| afaD | 0 (0.0) | 0 (0.0) | 1 (0.2) | 1 (2.6) | 2 (0.3) | 0.23 |
| iutA | 19 (54.3) | 20 (37.7) | 48 (9.8) | 17 (44.7) | 104 (16.8) | <2.2E-16 |
| fyuA | 16 (45.7) | 22 (41.5) | 402 (81.7) | 19 (50.0) | 459 (74.3) | 3.08E14 |
| focG | 0 (0.0) | 2 (3.8) | 193 (39.2) | 1 (2.6) | 196 (31.7) | <2.2E-16 |
| hlyD | 7 (20.0) | 3 (5.7) | 313 (63.6) | 3 (7.9) | 326 (52.8) | <2.2E-16 |
| cnf1 | 7 (20.0) | 2 (3.8) | 315 (64.0) | 2 (5.3) | 326 (52.8) | <2.2E-16 |
| cdt3 | 0 (0.0) | 1 (1.9) | 0 (0.0) | 0 (0.0) | 1 (0.2) | 1 |
| fimH | 32 (91.4) | 47 (88.7) | 422 (85.8) | 32 (84.2) | 533 (86.2) | 0.78 |
| iroN | 17 (48.6) | 22 (41.5) | 294 (59.8) | 21 (55.3) | 354 (57.3) | 0.051 |
| ibeA | 6 (17.1) | 7 (13.2) | 162 (32.9) | 4 (10.5) | 179 (29.0) | 1.65E-4 |
| iss | 9 (25.7) | 16 (30.2) | 59 (12.0) | 12 (31.6) | 96 (15.5) | 4.56E-05 |
| eae | 2 (5.7) | 1 (1.9) | 5 (1.0) | 0 (0.0) | 8 (1.3) | 0.113 |
| Median VS2 | 3 | 3 | 6 | 4 | 6 | – |
| IQ min | 1 | 0 | 0 | 0 | 0 | – |
| IQ max | 9 | 8 | 10 | 8 | 10 | – |
| ExPEC | 14 (40.0) | 7 (13.2) | 333 (67.7) | 15 (39.5) | 369 (59.7) | 2.54E-16 |
| UPEC | 7 (20.0) | 2 (3.8) | 263 (53.5) | 2 (5.3) | 274 (44.3) | 9.41E-22 |
1Numbers indicate p-values (Fisher’s exact test). Numbers in bold indicate statistically significant values. 2p-value (Fisher’s exact test) calculated from the number of positive isolates for each virulence gene among phylogroups. When the Fisher’s exact test was significant, an analysis and graphic visualization of the proportions and their 95% confidence intervals (CI) was performed. A proportion was considered significant when its CI did not overlap at least with one other CI. 2VS is the Median virulence-associated gene Score calculated as the sum of virulence genes found positive using PCR. IQ: interquartile range of the virulence gene scores. ExPEC status was defined as the presence of ≥2 of the following genes: papA, focG, kpsMTII, sfaS, afaD, and iutA. UPEC status was defined as the presence of the hlyD and cnf1 genes among ExPEC isolates. The virulence genes cnf2, stx1, stx2, aggR, and cdt3 were absent from this population of isolates.