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With the benefit of hindsight from this study,1 which refuted the perception that convulsive status epilepticus is atypical of acute bacterial meningitis (ABM), cerebrospinal fluid (CSF) sampling might have been more readily undertaken, and perhaps more blood cultures done, given the fact that the latter modality sometimes tests positive even when CSF Gram stains are non-contributory.
The crux of the matter is how the index of suspicion for meningitis is “packaged”, and the bottom line is that, given the fact that both ABM and tuberculous meningitis (TBM) are eminently amenable to treatment, and without treatment death is an almost invariable outcome for both, common ground must be found in the “packaging” in order to optimise diagnostic potential. A package which does not acknowledge the true prevalence of disease manifestations risks relegating those stigmata to oblivion, the latter being the fate of the blanching maculopapular rash which, notwithstanding its prevalence of 13% in meningococcaemia,2 nevertheless totally escaped mention in the section on ABM in a leading textbook.3 With a prevalence of 6.5–9.7% in ABM, the CSF which is characterised by normal cellularity and biochemistry4,5 is another parameter that deserves greater recognition than is usually the case, especially because this is a feature which may characterise TBM as well.6,7 One view is that, in the latter context coexisting HIV/AIDS is the operative factor for this manifestation of TBM.6
What is also evident from the HIV/AIDS epidemic, is that tuberculous patients who harbour this virus are more likely to have extrapulmonary tuberculosis than their counterparts who do not have HIV/AIDS.8 The paradigm shift dictated by the HIV/AIDS era is that the index of suspicion for miliary tuberculosis and, hence, TBM, should be correspondingly higher, and that parallels between ABM and TBM should be more readily recognised. For example, like the four patients reported with ABM in the absence of meningeal signs,1 the 8 month old HIV/AIDS patient with TBM reported by Janner et al also presented without any clinical signs of meningitis.7
Fundoscopy is crucial to the index of suspicion for miliary tuberculosis and, hence, TBM, given the fact that the presence of choroidal tubercles will reveal the miliary component even when routine chest radiography has failed to do so.9 Among 113 confirmed cases of miliary tuberculosis, 12.4% were undetected by chest x ray.9 Choroidal tubercles were detected by fundoscopy in five of the 14 x ray negative cases.9
The armamentaria for the heightened index of suspicion for ABM as well as for TBM include a more overt acknowledgment of the significance of the blanching maculopapular rash in ABM, routine fundoscopy to detect choroidal tubercles, a greater willingness to undertake CSF sampling and blood cultures in convulsive status epilepticus, and a recognition that a CSF which is normal for cell count and for biochemistry may be a feature of either ABM or TBM, and so may be the total absence of signs of meningeal irritation.
Competing interests: none declared