Diagnosis
The gold standard of diagnosis is isolation of N. meningitidis from sterile body fluid. A cerebrospinal fluid (CSF) specimen is sent to the laboratory immediately for identification of the organism. Diagnosis relies on culturing the organism on a chocolate agar plate. Further testing to differentiate the species includes testing for oxidase, catalase (all clinically relevant Neisseria show a positive reaction) and the carbohydrates maltose, sucrose, and glucose test in which N. meningitidis will ferment (that is, utilize) the glucose and maltose. Serology determines the subgroup of the organism.
If the bacteria reach the circulation, then blood cultures should be drawn and processed accordingly.
Clinical tests that are used currently for the diagnosis of meningococcal disease take between 2 and 48 hours and often rely on the culturing of bacteria from either blood or CSF samples. However, polymerase chain reaction tests can be used to identify the organism even after antibiotics have begun to reduce the infection. As the disease has a fatality risk approaching 15% within 12 hours of infection, it is crucial to initiate testing as quickly as possible but not to wait for the results before initiating antibiotic therapy.
Read more about this topic: Neisseria Meningitidis