Comparison of conventional bacteriology with polymerase chain reaction (PCR) technique for rapid diagnosis of tuberculous meningitis

Tuberculosis is more prevalent in developing countries and death from tuberculosis meningitis is strongly associated with delays in diagnosis and treatment. Polymerase chain reaction (PCR) has been incorporated as a diagnostic tool for the diagnosis of tuberculosis. The rapid results and greater sensitivity compared to traditional microbiological methods makes PCR a suitable technique in tuberculosis, especially in tuberculosis meningitis, when diagnosis is difficult or when rapid diagnosis is needed. However, the possibility of false positive and false negative results must be considered. The aim of this study was to compare the conventional bacteriology (culture Ziehl- Neelsen staining) with polymerase chain reaction (PCR) technique for rapid diagnosis of tuberculosis meningitis. This study included 25 clinically diagnosed patients that were suspected to have tuberculosis meningitis and 10 other bacterial or viral meningitis patients were investigated. DNA was extracted from CSF and the NESTED PCR using specific primers were done. In 25 samples, Mycobacterium tuberculosis DNA was detected in 9 (36%) by PCR, 2(8%) and 1(4%) with culture and direct smear was obtained, respectively. whereas no DNA bands were detected in patient with the other 10 meningitis. The entire procedure was repeated and the same result was obtained. The findings of this study indicated that PCR is a powerful method for rapid and sensitive diagnosis of tuberculosis meningitis. In a way that it decreases obtaining the results from several weeks in bacteriological methods to one to two days, especially in smear negative patients. This is very important in tuberculosis meningitis because it is a medical urgency and needs rapid diagnosis and early treatment.