Table 4. Number and proportion of TB cases, by time between treatment initiation and drug resistance acquisition and by acquired drug resistance categories, England, Wales, and Northern Ireland, 2000–2015*.
| Time between treatment start and acquired resistance |
Acquired drug resistance category |
|||
| No MDR TB before or after acquiring resistance, no. (%) |
Acquired resistance and MDR TB developed later, no. (%) |
Initial MDR TB with additional resistance acquired later, no. (%) |
Total with acquired drug resistance, no. (%) |
|
| <1 mo | 20 (36.4) | 2 (5.1) | 5 (11.9) | 27 (19.9) |
| 2 mo | 10 (18.2) | 0 | 13 (31.0) | 23 (16.9) |
| 3 mo | 8 (14.5) | 3 (7.7) | 4 (9.5) | 15 (11.0) |
| 4–6 mo | 6 (10.9) | 9 (23.1) | 10 (23.8) | 25 (18.4) |
| 7–9 mo | 4 (7.3) | 8 (20.5) | 5 (11.9) | 17 (12.5) |
| 10 mo–1 y | 4 (7.3) | 7 (18.0) | 1 (2.4) | 12 (8.8) |
| >1 y |
3 (5.5) |
10 (25.6) |
4 (9.5) |
17 (12.5) |
| Total | 55 (100) | 39 (100) | 42 (100) | 136 (100) |
*MDR, multidrug-resistant; TB, tuberculosis.