Table 4.
RNA-based prediction of antipseudomonal antibiotic resistance and agreement with disk diffusion.
| RNA-based prediction | Drugs | Agreement with disk diffusion (number of strains; %) | Minor error | Major error | Very major error |
|---|---|---|---|---|---|
| Highly reduced | imipenem | 28 | 5 | 0 | 5 |
| oprD expressiona | 73.7% | 13.2% | 0.0% | 13.2% | |
| meropenem | 30 | 3 | 1 | 4 | |
| 78.9% | 7.9% | 2.6% | 10.5% | ||
| Derepressed | PIP/TAZOc | 36 | 4 | 1 | 0 |
| ampCb | 87.8% | 9.8% | 2.4% | 0.0% | |
| ceftazidime | 38 | 1 | 1 | 1 | |
| 92.7% | 2.4% | 2.4% | 2.4% | ||
| cefepime | 37 | 1 | 2 | 1 | |
| 90.2% | 2.4% | 4.9% | 2.4% |
Highly reduced oprD mRNA expression, defined as 5 times less expressed than PAO1 level measured by RT-qPCR, predicted carbapenem resistance, otherwise susceptible.
Derepressed ampC mRNA, defined as 15 times more produced than PAO1 level without induction measured by RT-qPCR, predicted piperacillin/tazobactam, ceftafidime and cefepime resistance, otherwise susceptible.
PIP/TAZO corresponds to piperacillin/tazobactam combination. The error rate determination is as follow: Minor error – reference result is R or S and device result is I; reference result is I and device result is R or S. Major error – reference result is S and device result is R. Very major error – reference result is R and device result is S.