Lovely Seminar in The Lancet from McGill, Solomon et al on Acute Bacterial Meningitis in Adults from August 2016.
Suspected bacterial meningitis has particular challenges, the assessing doctor has to have the very best clinical skills and use them quickly.
Most of the patients you suspect have meningitis will not have it; most of those who do have it will have viral meningitis which is self-limiting. Separating out those who don't have meningitis from those who do, and what sort it is requires a lumbar puncture; it is a difficult clinical decision and to make it harder the quicker this decision is made the better.
The outcome for patients with bacterial meningitis is better if they have a precise microbiological diagnosis, and ideally this means CSF is sampled before the antibiotics are given, and the outcome is better if patients receive (the correct) antibiotics early. So the clinical assessment, to decide on that lumbar puncture has to be done quickly and extremely well.
A CT is often requested, and is more often than not unnecessary, worse it delays clinical decision making and action.
Finally the lumbar puncture is a technically demanding procedure, especially if is to be done quickly.
McGill, Solomon et al's seminar gives the global scope to the problem, from epidemiology, through the success of vaccines, to the molecular biology but does allow the UK physician to focus on the areas of relevance to them and their patients - steady the nerves, get the CSF sampled and give the antibiotics and dexamethasone quickly. Do not seek comfort in an unnecessary CT scan.