When we analyzed DRS data obtained from the most stable three-gene combination (GUSB–PGK1–TBP) we observed that the expression signature can properly discriminate between viral and bacterial infections (Fig. 3A; P-value = 1.04 × 10−4; AUC = 92.2% [95% CI: 81.9–100%]). The gene discussed is PGK1; the disease is bacterial infectious disease.