TABLE 3.
Accuracy of genotypic prediction rules V.2 when applied to the German test set
| Antimicrobial | Total no. of isolates | Phenotypic susceptibility rate, % | Genotype used for prediction (V.2) | Categorical agreement, % | Very major error rate (FN), % (95% CI) | Major error rate (FP), % (95% CI) | PPV, % | NPV, % |
|---|---|---|---|---|---|---|---|---|
| Ampicillin | 50 | 0 | Mutation of pbp5 485M or presence of 466′S/D | 100 | 0 (0, 7) | NAa | 100 | NA |
| Vancomycin | 50 | 20 | Presence of vanA or vanB Flag isolates with vanHAX but without vanRS as potential VVE | 100 | 0 (0, 8.8) | 0 (0, 31) | 100 | 100 |
| Gentamicin, high levelb | 13 | 30 | Presence of aac(6′)-le-aph(2”)-la | 69 | 10 (0.25, 44) | 100 (29, 100) | 75 | 0 |
| Ciprofloxacinc | 50 | 0 | Mutation of gyrA (84S) or parC (82S) | 100 | 0 (0, 7) | NA | 100 | NA |
| Levofloxacinc | NA | Mutation of gyrA (84S) or parC (82S) | ||||||
| Tetracycline | 50 | 56 | Presence of tet(L), tet(M), or tet(S) | 94 | 0 (0, 17) | 3.6 (0, 18) | 95 | 90 |
| Doxycycline | NA | Presence of tet(M) flag isolates with tet(M) L528F as indeterminant | ||||||
| Linezolidc | 50 | 96 | Mutation of 23S rRNA G2576T in at least 3 alleles | 100 | 0 (0, 84) | 0 (0, 7.4) | 100 | 100 |
a
NA, not available.
b
Gentamicin was only tested on a subset of isolates using an alternative phenotypic method from that used in the derivation and validation sets. For all three isolates that were phenotypically susceptible, the gentamicin MIC was 128 μg/mL, which is 1 dilution below the EUCAST breakpoint, and the isolate contained the aac(6′)-Ie-aph(2″)-Ia gene.
c
Antibiotic for which intermediate isolates were considered with susceptible isolates.