Table 2.
Most frequently occurring serogroups and virulence genes among the 460 pathogenic and nonpathogenic isolates used for statistical analysis
| Serogroup or virulence genea | % Total isolatesb |
|
|---|---|---|
| Pathogenic (n = 352) | Nonpathogenic (n = 108) | |
| Serogroup | ||
| O78* | 17.6 | 0.9 |
| O2* | 17.3 | 4.6 |
| O8 | 2.0 | 4.6 |
| O18 | 9.0 | 5.6 |
| O5 | 4.5 | 2.8 |
| O1 | 6 | 3.7 |
| Total | 56.5 | 22.2 |
| Virulence genes | ||
| sitA* | 96.3 | 59.3 |
| F1* | 86.4 | 71.3 |
| iutA* | 82.7 | 26.9 |
| tsh* | 52.8 | 16.7 |
| frzorf4* | 53.4 | 16.7 |
| tkt1* | 50.6 | 16.7 |
| aec4* | 46.9 | 13.9 |
| P(F11)* | 30.4 | 7.4 |
| aec26* | 34.4 | 6.5 |
| neuC* | 27.0 | 5.6 |
| F17 | 5.7 | 4.6 |
| sfa-focDE† | 9.1 | 4.6 |
| afa-draBC | 4.0 | 6.5 |
| cdt† | 9.1 | 1.9 |
| eae† | 2.0 | 12.0 |
a
*, Significant differences (P < 0.001) were observed between pathogenic and nonpathogenic strains; †, significant differences (P < 0.015) were observed between pathogenic and nonpathogenic strains. Strains were noted as F1 positive when both fimA (or the fimAvMT78 variant) and fimH genes were present and P(F11) positive when the three genes—felA, papC, and a variant of papG—were present.
b
For pathogenic strains, of five chicks inoculated subcutaneously, one to five died; for nonpathogenic strains, none of five chicks inoculated subcutaneously died.