Procalcitonin for the diagnosis of bacterial infections and guide antibiotic treatment for patients with specific symptoms

Method for the diagnosis of a bacterial infection in a patient presenting in the emergency room with nonspecific symptoms (QNE), comprising the steps of: (i) determining the level of procalcitonin (PCT) or a fragment thereof of at least 12 amino acids in length in a sample of a patient who presented with non-specific symptoms, and (ii) determining whether said patient has a bacterial infection or not by comparing said determined level of PCT with a threshold predetermined level wherein the predetermined threshold level is between 0.02 ng / ml and 0.25 ng / ml and in which the patient does not have one of the following: pain (thoracic, abdominal, head, leg joint, back), dyspnea, coughing, weakness (localized), symptoms of stroke type, swollen limb (leg, limb), diarrhea, dysuria, GCS <14, confusion, intoxication, crisis, bleeding, syncope, anxiety, psychotic symptoms, ideas suicide, skin injury, allergic skin reaction, fever, dizziness, palpitations, nausea vomiting, trauma.