Diagnosing pneumococcal infections

Several different tests can be used to diagnose pneumococcal infections. The tests you have will depend on your symptoms.

Some of the tests used are outlined below.

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 test 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 lung, 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:

Blood pressure test

You may have a blood pressure test as a serious infection can often lead to a decrease in blood pressure. 

Lumbar puncture test

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. If the sample contains infection-fighting white blood cells and/or bacteria, it may indicate you have meningitis.

Urinary antigen test

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

It involves taking a urine sample and then carrying out a technique known as an immunochromatographic assay. This is able to detect the distinctive protein molecules that make up the outer shell of the S. pneumoniae bacteria.

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