An in-house loop-mediated isothermal amplification (LAMP) method was established for the detection of Salmonella Typhi and Salmonella Paratyphi A using primers that were designed based on gene coding for putative regulatory protein in S. Typhi (STY4220) and S. Paratyphi A (SSPA3213). This established in-house LAMP assay gave positive results to all the 14 S. Typhi and 20 S. Paratyphi A isolates used in this study and negative to 20 other Salmonella and 19 non-Salmonella bacteria. When tested on 60 clinical samples, it gave positive results to 10 clinical samples containing either S. Typhi or S. Paratyphi A and negative to the other 50 samples, which were similar to those results obtained by gold standard culture method. Because of its rapidity and simplicity, this LAMP offers a promising method for the detection of both S. Typhi and S. Paratyphi A for screening purposes at resource-limited settings.
Current detection methods for S. Typhi and S. Paratyphi A have several limitations; culture method is time-consuming and laborious, while polymerase chain reaction-based methods require expensive equipments and trained personnel which are usually not available in the low-resource setting. Therefore, LAMP established in this study offers a simple, rapid, sensitive and specific method for the screening of S. Typhi and S. Paratyphi A especially at resource-limited settings.