Table 2. Resistance levels for colistin in Escherichia coli and Klebsiella pneumoniae isolates from the national antimicrobial resistance surveillance database, the Netherlands, 2011–2015 (n = 132,116).
| Year | Number of tested isolates | Colistin-resistant isolates | ||
|---|---|---|---|---|
| n | % | 95% CI | ||
| Escherichia coli | ||||
| 2011 | 19,651 | 71 | 0.4 | 0.3–0.4 |
| 2012 | 25,724 | 119 | 0.5 | 0.4–0.5 |
| 2013 | 24,882 | 104 | 0.4 | 0.3–0.5 |
| 2014 | 20,999 | 89 | 0.4 | 0.3–0.5 |
| 2015 | 20,589 | 105 | 0.5 | 0.4–0.6 |
| Klebsiella pneumoniae | ||||
| 2011 | 3,727 | 45 | 1.2 | 0.9–1.6 |
| 2012 | 4,485 | 43 | 1.0 | 0.7–1.2 |
| 2013 | 4,267 | 61 | 1.4 | 1.1–1.8 |
| 2014 | 3,813 | 39 | 1.0 | 0.7–1.3 |
| 2015 | 3,979 | 45 | 1.1 | 0.8–1.5 |
CI: confidence interval.