LOOP MEDIATED ISOTHERMAL AMPLIFICATION FOR THE RAPID DIAGNOSIS OF PULMONARY TUBERCULOSIS

BACKGROUNDControl of tuberculosis is often challenged by diagnostic methods which are time consuming, often less sensitive, expensive and inaccessible to most patients especially in the developing countries.The characteristics of loop-mediated isothermal amplification (LAMP) method make it a promising platform for the molecular detection of tuberculosis in developing countries.We wanted to evaluate the loop mediated isothermal amplification method for the rapid diagnosis of pulmonary tuberculosis (PTB) in low resource settings. METHODSWe conducted an observational study in the Microbiology department for a period of eighteen months on sputum samples collected from suspected cases of pulmonary tuberculosis which satisfied the inclusion as well as exclusion criteria.All these samples after processing were subjected to smear microscopy by acid fast staining, culture on Lowenstein-Jensen (LJ) medium and LAMP assay and results were compared to derive sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). RESULTSA total of 110 samples were included in the study.Using culture as the reference standard, we found that the sensitivity and specificity for TB-LAMP assay were 98.3% and 98.03% respectively and PPV and NPV were 98.3% and 98.03% respectively.The AFB staining had a sensitivity of 91.5% and specificity of 98%. CONCLUSIONSHence LAMP method is a reliable test for the diagnosis of tuberculosis which can be suited to resource limited settings.The method has very good positive and negative predictive value for pulmonary samples.It is a rapid technique when compared to conventional culture and simple and less expensive than other molecular based methods.Therefore, it can be applied as a point of care testing (POCT) method in resource limited settings.