The <i>S. aureus</i> infection whole blood transcriptional signature is characterized by over-expression of myeloid lineage transcripts and under-expression of lymphoid lineage transcripts.

<p><b>A.</b> Statistical group comparison between 22 healthy subjects and 40 patients with acute <i>S. aureus</i> infection (non-parametric test, α = 0.01, Benjamini-Hochberg multiple testing correction, 1.25 fold change) yielded 1,422 differentially expressed transcripts. Transcripts were organized by hierarchical clustering (Spearman) according to similarities in expression profiles. Each row represents a transcript and each column an individual subject. Normalized log ratio levels are indicated by red (over-expressed) or blue (under-expressed), as compared to the median of healthy controls. <b>B.</b> The same 1,422 transcript list and hierarchical clustering were applied to an independent test set of 22 healthy controls and 59 patients with acute <i>S. aureus</i> infection. Sample hierarchical clustering (Spearman) was performed on the 1,422 transcript list in the test set. <b>C.</b> Average modular transcriptional fingerprrint for <i>S. aureus</i> patients as compared to healthy controls in the training set. <b>D.</b> Average modular transcriptional profile for <i>S. aureus</i> patients as compared to healthy controls in the test set. <b>E.</b> Module functional annotations legend. <b>F.</b> Scatter plot comparing module expression between training (x-axis) and test (y-axis) sets. Spearman correlation was applied.