Diagnosis and Tests for Meningitis

Meningitis cannot be diagnosed at home. Doctors confirm it with an examination and tests. In suspected bacterial meningitis, antibiotics are started as soon as possible, sometimes before all tests are back.

Examination

The doctor checks fever, neck stiffness, light sensitivity, drowsiness, rash and in babies, the soft spot on the head. Blood pressure, heart rate and breathing are also checked.

Blood tests

• Blood culture to find the bacteria
• Full blood count and inflammation markers such as CRP
• Blood sugar, kidney and liver tests
• PCR tests for certain bacteria and viruses

Lumbar puncture (spinal tap)

A thin needle takes a sample of spinal fluid from the lower back. The fluid is tested for cells, protein, sugar, germs and DNA. It is the key test. A CT scan may be done first if there are signs of raised pressure in the brain.

Imaging

CT or MRI of the brain may be done to look for swelling, abscess or other problems.

Other tests

• Tests for TB, such as CBNAAT or GeneXpert on spinal fluid
• HIV test and fungal tests
• Throat or skin swabs in some cases

What the results show

• Bacterial: cloudy fluid, many white cells and low sugar
• Viral: mildly raised cells and normal sugar