System Can Help Distinguish Between Tuberculous and Bacterial Meningitis
January 8, 2003
Researchers in the United Kingdom and Vietnam have identified a series of clinical and laboratory variables that can be used to quickly and accurately diagnose tuberculous meningitis. Their system is designed to help health workers distinguish tuberculous meningitis from meningitis caused by other bacterial infections.Adapted from:
"The diagnosis of tuberculous meningitis is difficult," wrote G.E. Thwaites and colleagues at the University of Oxford and the Oxford-affiliated Center for Tropical Diseases in Ho Chi Minh City. "Discrimination of cases from those of bacterial meningitis by clinical features alone is often impossible, and current laboratory methods remain inadequate or inaccessible in developing countries."
The researchers examined features common to more than 250 Vietnamese adults with confirmed TM. The authors created a diagnostic rule and a classification tree from prognostically useful factors. Data showed five variables -- age, total and cerebrospinal fluid (CSF) leukocyte counts, CSF neutrophil proportions, and length of history -- were independently predictive of tuberculous meningitis. The classification tree derived from these features was 99 percent sensitive and 93 percent specific in resubstitution tests, with a sensitivity and specificity of 88 percent and 70 percent respectively when used prospectively, according to the report. The diagnostic rule derived from the variables produced similar -- though slightly less impressive -- results. The full report, "Diagnosis of Adult Tuberculous Meningitis by Use of Clinical and Laboratory Features," was published in the Lancet (2002;360(9342):1287-1292).
"This study suggests that simple clinical and laboratory data can help in the diagnosis of adults with tuberculous meningitis," Thwaites and colleagues concluded. "Although the usefulness of the diagnostic rule will vary depending on the prevalence of tuberculosis and HIV-1 infection, we suggest it be applied to adults with meningitis and a low cerebrospinal fluid glucose, particularly in settings with limited microbiological resources."
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This article was provided by CDC National Prevention Information Network. It is a part of the publication CDC HIV/Hepatitis/STD/TB Prevention News Update.