Comparative study of Amplicor polymerase chain reaction and ligase chain reaction for direct detection of M-tuberculosis in clinical specimens

Objective: To compare the sensitivity and specificity of two deoxyribonucle ic acid amplification techniques, Amplicor polymerase chain reaction and Li gase chain reaction in the detection of M.tuberculosis in clinical specimen s. Methods: At a 350-bed general hospital in Jeddah, Saudi Arabia, 326 patient samples were selected for this study on the basis of positive smear for ac id fast bacilli, history of mycobacterial disease or culture positivity, or both. Each sample in addition to microscopy and culture, was tested by bot h Amplicor polymerase chain reaction and ligase chain reaction Results: Of the 326 patient samples, 74 specimens were culture positive for M.tuberculosis and 46/74 (62%) were acid fast bacilli smear positive, All the 46 smear positive-M.tuberculosis positive cultures were ligase chain re action positive (100%) and 44 (95.6%) were positive by Amplicor polymerase chain reaction, In the 28 smear negative M.tuberculosis positive cultures, 25 (89.3%) were ligase chain reaction positive and 21(75.0%) were Amplicor polymerase chain reaction positive. Of all specimens, 68/325 (20.9%) were c ulture positive for non tuberculous mycobacteria and all were negative by A mplicor polymerase chain reaction and ligase chain reaction. Conclusion: The high specificity of both methods allows for differentiation of M.tuberculosis from non tuberculous mycobacteria, The use of deoxyribon ucleic acid amplification techniques allows for rapid and specific diagnosi s of M.tuberculosis, thus eliminating unnecessary administration of antitub erculosis therapy and isolation measures for non-tuberculous mycobacteria p atients.