Grup A Streptokokların Hızlı Moleküler Tanısında Loop-Mediated Isothermal Amplifi cation PCR (LAMP-PCR)

Objective: Most bacterial pharyngitis is caused by Group A Streptococci (GAS). Therefore, discrimination between bacterial-viral causes, and rapid diagnosis of GAS are important in terms of guiding treatment in acute tonsillopharyngitis cases. The present study aims to assess the effi cacy ofLoop-Mediated Isothermal Amplifi cation PCR (LAMP PCR) test for rapid diagnosis of GAS, and compare its correlation with culture tests as conventional methods in children with suspected acute bacterial tonsillopharyngitis. Materials and Methods: We studied 36 GAS strains isolated from swab samples obtained from posterior pharynges and tonsils of patients presenting to Sakarya University Training and Research Hospital with acute tonsillopharyngitis symptoms, pharyngeal swab samples from 8 patients who had concurrent positive pharyngeal culture results for GAS, and one standard Streptococcus pyogenesstrain (ATCC 19615). Isolated GAS strains were analyzed with LAMP PCR. As target region, Streptoplysin B (speB) gene region was selected. Extraction, amplifi cation and analysis of the results were performed with LAMP PCR analyzer (Genie II, Optigene, UK), and all these procedures were completed within 70 minutes. Result graphics obtained from LAMP PCR analyzer were evaluated with Genie Explorer v2.0.6.3 (Optigene, UK) program. Results: LAMP PCR method yielded positive results for 97.2% (35/36) of GAS strains isolated from patient samples. Pharyngeal swab samples of 8 patients who had concurrent positive culture results for GAS were analyzed, and 7 of them (87.5%) had positive GAS results with LAMP PCR. Standard strain sample which was analyzed with duplicate run was also detected as positive. With enzymatic method, DNA isolation (~30 minutes) and isothermal amplifi cation process (~40 minutes) were completed in ~70 minutes. Conclusion: LAMP PCR has high sensitivity and specifi city with pretty simple and practical extraction procedure. A single small portable device is suffi cient for isolation, amplifi cation and analysis of the results, with the whole process taking only as short as 45-70 minutes. It is a convenient method requiring minimal laboratory equipment, and the results can be evaluated visually. It is more affordable compared to other molecular tests. Since LAMP PCR has been introduced recently to clinical practice, more comprehensive studies are necessary.