| History: Symptoms of an infection vary greatly, depending on the primary site of infection. For example, meningitis is associated with headache, stiffness, and pain in the neck and involves difficulty turning and bending the head, whereas appendicitis is associated with pain in the lower abdomen and involves nausea and vomiting. Symptoms of an upper respiratory infection may include headache, cough, and nasal discharge. Symptoms of a gastrointestinal infection may include nausea, vomiting, and diarrhea. The common cold is a systemic viral infection with symptoms that may include fever, aching muscles (myalgias), and a vague feeling of discomfort or illness (malaise). Physical exam: Physical examination findings depend on where the infection is located. When examined by touch (palpated), the area around a local infection may feel warm. Touching the area may elicit pain. In general, the affected area may be red, warm, and/or tender. Discharge from an abscess may be present. A systemic infection may not cause any specific physical abnormalities. Diagnosis may rely on history, symptoms, and testing. Vital signs, including pulse, blood pressure, respiration, and temperature, may be affected. Tests: A complete blood count (CBC) with differential or an erythrocyte sedimentation rate can indicate the presence of an infection irrespective of its site. Examining the stool for white blood cells may indicate an infectious process if it involves the gastrointestinal tract. A microbial culture of an infected site often identifies the organism responsible for the infection.
Based on the location of an infection, tests that assess the extent of the infection include chest x-ray, abdominal ultrasound, sinus films, CT, spinal tap, or MRI. Fluid from an infected site should be obtained whenever possible for culture and sensitivity, especially before antibiotics are started, to optimize the opportunity for a positive culture. This may involve removal (aspiration) of the fluid with a needle and syringe. |