Aside from cerebrospinal fluid, appropriate materials for the diagnosis of meningococcal disease are blood cultures, throat swabs and scratches, aspirations and biopsies of the skin rash.
Whenever bacterial meningitis is suspected, antibiotics should be given immediately, without waiting for diagnostic test results.
The diagnosis of meningitis is ultimately based on evaluation of the cerebrospinal fluid. Therefore, a lumbar puncture is indicated whenever such a diagnosis is seriously considered. It is performed to gain material for investigation under the microscope and cell cultures. Because of the rapid course of the disease and the possibility that other bacteria could be the reason for the patientís condition, broad-spectrum antibiotic treatment (such as penicillin or 3rd generation cephalosporins) is usually started before the diagnosis can be confirmed by lab tests.
The most prominent changes in the cerebrospinal fluid are a decreased sugar content, an elevated protein concentration and a high polymorphonuclear cell count (changes in the shape and size of cells).