Proportion of Escherichia coli, Klebsiella pneumoniae, K. oxytoca and Proteus mirabilis blood culture isolates that produced extended-spectrum β-lactamase, including proportion of ST131 clonal type within E. coli isolates that produced extended-spectrum β-lactamase, 2006–2016
| Organism | Year; no. (%) of isolates | p value* | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | ||
| Escherichia coli | 19/296 (6.4) | 13/309 (4.2) | 29/355 (8.2) | 28/376 (7.4) | 33/394 (8.4) | 51/428 (11.9) | 58/457 (12.7) | 81/485 (16.7) | 65/485 (13.4) | 76/516 (14.7) | 89/513 (17.3) | < 0.001 |
| Klebsiella pneumoniae | 6/120 (5.0) | 5/109 (4.6) | 5/87 (5.7) | 0/115 (0.0) | 6/139 (4.3) | 9/136 (6.6) | 4/129 (3.1) | 8/162 (4.9) | 11/154 (7.1) | 9/191 (4.7) | 18/196 (9.2) | 0.04 |
| K. oxytoca | 0/4 (0.0) | 3/20 (15.0) | 3/23 (13.0) | 1/25 (4.0) | 1/22 (4.5) | 0/18 (0.0) | 1/23 (4.3) | 0/23 (0.0) | 1/30 (3.3) | 0/40 (0.0) | 0/33 (0.0) | 0.002 |
| Proteus mirabilis | 0/23 (0.0) | 0/30 (0.0) | 0/26 (0.0) | 0/27 (0.0) | 0/34 (0.0) | 0/31 (0.0) | 2/38 (5.3) | 0/30 (0.0) | 0/32 (0.0) | 0/36 (0.0) | 1/35 (2.8) | 0.3 |
| ST131 clonal type among ESBL-producing E. coli | 6/19 (31.6) | 8/13 (61.5) | 20/28 (71.4) | 16/26 (61.5) | 19/32 (59.4) | 27/46 (58.7) | 36/58 (62.1) | 54/80 (67.5) | 40/65 (61.5) | 48/76 (63.2) | 65/89 (73.0) | 0.03 |
Note: ESBL = extended-spectrum β-lactamase.
↵* For the trend observed between 2006 and 2016 (χ2 test for trend).