Table. Escherichia coli O157:H7 lineage frequency by case characteristic among culture-confirmed human cases reported in Washington, USA, 2005–2014*.
| Variable | Lineage Ib | Lineage IIa | Lineage IIb | Rare lineages† |
|---|---|---|---|---|
| Total |
586 (52.7) |
260 (23.4) |
199 (17.9) |
66 (5.9) |
| Mean isolates per PFGE type
(SD)‡ |
2.8 (5.3) |
6.8 (14.3) |
7.7 (24.7) |
1.5 (1.7) |
| Sex | ||||
| F | 333 (56.8) | 163 (62.7) | 105 (52.8) | 33 (50.0) |
| M | 244 (41.6) | 97 (37.3) | 94 (47.2) | 32 (48.5) |
| Unknown |
9 (1.5) |
0 |
0 |
1 (1.5) |
| Age group, y | ||||
| <5 | 119 (20.3) | 72 (27.7) | 63 (31.7) | 10 (15.2) |
| 5–9 | 81 (13.8) | 32 (12.3) | 33 (16.6) | 12 (18.2) |
| 10–19 | 97 (16.6) | 51 (19.6) | 31 (15.6) | 6 (9.1) |
| 20–59 | 207 (35.3) | 81 (31.2) | 49 (24.6) | 29 (43.9) |
| ≥60 | 81 (13.8) | 24 (9.2) | 23 (11.6) | 9 (13.6) |
| Unknown |
1 (0.2) |
0 |
0 |
0 |
| HUS | ||||
| Yes | 37 (6.3) | 18 (6.9) | 20 (10.0) | 0 |
| No | 526 (89.2) | 236 (90.1) | 173 (86.1) | 67 (98.5) |
| Unknown | 27 (4.6) | 8 (3.1) | 8 (4.0) | 1 (1.5) |
*Values are no. (%) except as indicated. HUS, hemolytic uremic syndrome; PFGE, pulsed-field gel electrophoresis. †Twelve clinically rare lineages. ‡PFGE type percentages indicate the proportion of PFGE types with an assigned lineage (n = 355) belonging to each lineage.