TABLE 4.
Numbers of very major and major errors, sensitivity, and specificity calculated for EUCAST disk diffusion and CLSI agar screen methods, according to the country of the laboratories or their experience in using the detection methodsa
| Method | Country and experience (no. of laboratories) | VME rate (% [no. of VMEs/total no. resistant]) | Sensitivity (95% CI) | ME rate (% [no. of MEs/total no. susceptible]) | Specificity (95% CI) |
|---|---|---|---|---|---|
| Disk diffusion | Sweden (10) | 1.9 (5/270) | 0.98 (0.95–0.99) | 0 (0/30) | 1 (0.86–1) |
| Norway (13) | 10 (36/351) | 0.90 (0.86–0.93) | 2.6 (1/39) | 0.97 (0.85–1) | |
| Denmark (5) | 8.9 (12/135) | 0.91 (0.85–0.95) | 6.7 (1/15) | 0.93 (0.66–1) | |
| Experienced (13) | 2.6 (9/351) | 0.97 (0.95–0.99) | 0 (0/39) | 1 (0.89–1) | |
| Inexperienced (15) | 11 (44/405) | 0.89 (0.86–0.92) | 4.4 (2/45) | 0.96 (0.84–0.99) | |
| Agar screen | Sweden (1) | 3.7 (1/27) | 0.9 (0.79–1) | 0 (0/3) | 1 (0.31–1) |
| Norway (13) | 6.8 (24/351) | 0.93 (0.90–0.95) | 0 (0/39) | 1 (0.89–1) | |
| Denmark (4) | 6.5 (7/108) | 0.94 (0.87–0.97) | 25 (3/12) | 0.75 (0.43–0.93) | |
| Experienced (13) | 6.8 (24/351) | 0.93 (0.90–0.95) | 0 (0/39) | 1 (0.89–1) | |
| Inexperienced (5) | 5.9 (8/135) | 0.94 (0.88–0.97) | 20 (3/15) | 0.8 (0.51–0.95) |
a
In VMEs, strains were classified as susceptible when containing the van genotype. In MEs, strains were classified as resistant when containing no van genotype.