Fig. 7

Absolute quantification of Aspergillus fumigatus using internal plasmid control PC1. A. Clinical respiratory samples were spiked with four different amounts of A. fumigatus (A. f) genome equivalents (GE) to generate a standard curve ranging from ˜ 3 to 1000 GE per PCR. Read counts from the internal plasmid control (PC) were used to normalize (A) f counts and a positive linear relationship (R2 = 0.89) with spiked GE was observed. (B) Using the linear model generated by the standard curve, A. f GE were estimated in 12 clinical respiratory samples known to be positive for A. f (plus one negative control sample containing no A. f). Estimated A. f GE for test samples were calibrated using the estimated A. f GE value of the negative control sample. The estimated A. f GE values displayed strong correlation (Spearman’s rank-order correlation; r [11] 0.78, p < 0.01) with known GE (calculated by rRNA qPCR)