A 15 year old girl presents to A&E with headache, vomiting, neck stiffness and photophobia. No rash was seen on examination. Her temperature is 38.3°C, heart rate is 90 bpm and respiratory rate is 18/min. What is the SINGLE most appropriate investigation?
A. Blood culture
B. Blood glucose
C. Lumbar puncture
D. Chest X-ray
E. CT head
She has signs of meningitis.
If the patient has got a rash, then perform blood culture as the diagnosis is most likely meningococcal septicaemia. The causative organism is Neisseria meningitides.
If there is no rash then a lumbar puncture would be a better answer, but this can only be done if there are no signs of raised intracranial pressure.
Generally, treatment for meningitis should be started before doing any investigations due to the seriousness of the disease.