The present invention provides methods of detecting infection using biomarkers. The methods disclosed herein include measuring the expression level of one of more polypeptide determinant in which the alteration of the expression level indicates infection of the patient in a sample of the subject and determining a clinically significant alteration in the level of the one or more polypeptides in the sample, wherein the alteration indicates an infection in the subject. The methods provided herein are for distinguishing between bacterial infection, mixed infection and/or viral infection.