Rapid detection of Helicobacter pylori using cytotoxin-associated gene A based on loop-mediated isothermal amplification assay and magnetic nanoparticles

The current methods for detecting Helicobacter pylori infection are time-consuming and have relatively low sensitivity. More appropriate tests are needed. A rapid, specific, and sensitive method was presently developed to detect the cytotoxin-associated gene A (cagA) of H. pylori. Genomic DNA was extracted using magnetic nanoparticles and then amplified by the loop-mediated isothermal amplification (LAMP) reaction using primers we designed. To assess the diagnostic value of the LAMP assay in detecting H. pylori cagA, agarose gel electrophoresis as well as detection of fluorescence intensity after adding fluorescent dye were done. Specificity analysis showed that 11 pathogenic bacterial strains common in human gut were negative for cagA, with a positive result obtained only for H. pylori. Sensitivity analysis demonstrated a cagA detection limit of 100 fg. The results were consistent with that of the C-3-urea breath test. The novel LAMP assay can directly identify H. pylori cagA in the gastric juice of clinical patients with high sensitivity and specificity. The comparatively more rapid and more sensitive method may be valuable for clinical applications.