Diagnosing pneumococcal infections

There are several ways to diagnose pneumococcal infections, and the tests you have will depend on your symptoms.

Physical examination

If a pneumococcal infection is suspected, your GP will listen to your chest with a stethoscope. The fluids produced during an invasive pneumococcal infection often cause a distinctive crackling sound.

Blood test

You may have a Blood tests to check for the presence of bacteria. A high number of infection-fighting white blood cells may indicate the presence of an infection. The blood sample can be sent to a laboratory so the bacteria that caused the infection can be identified.


Several different types of imaging tests may be used, depending on your symptoms.

X-rays may be able to highlight the presence of fluid in the lungs, which would indicate a lung infection. An X-ray uses radiation to produce images of the inside of the body.

Other imaging tests that may be used to investigate a potential pneumococcal infection include:

  • a computerised tomography (CT) scan
  • a magnetic resonance imaging (MRI) scan

Blood pressure test

Your blood pressure may bemeasured, as a serious infection can often lead to a decrease in blood pressure.

Lumbar puncture test

A lumbar puncture test involves taking a sample of cerebrospinal fluid (the fluid that surrounds the brain and spine) from the base of your spine and checking it for the presence of bacteria. A local anaesthetic will be used to numb the area.If the sample contains infection-fighting white blood cells and/or bacteria, it may indicate that you have meningitis .

Urinary antigen test

A urinary antigen test is a relatively new type of testused to help diagnose a pneumococcal infection.

It involves taking a urine sample, then carrying out a techniqueknown as an immunochromatographic assay. This can detect the distinctive protein molecules that make up the outer shell of the S. pneumoniae bacteria.

Content supplied by the NHS Website

Medically Reviewed by a doctor on 20 Jun 2016