Optimization of Loop-Mediated Isothermal Amplification Reaction for Detecting Streptococcus pneumoniae Serotypes in Clinical Nasopharynx Swab Samples

Abstract

Current molecular PCR-based methods for identifying Streptococcus pneumoniae, the primary cause of pneumonia, meningitis, and other invasive diseases, are accurate but require expensive infrastructure and have a long run time, which restricts their use, particularly in developing countries. LAMP, or loop-mediated isothermal amplification, is a low-cost alternative to polymerase chain reaction (PCR) that can be used quickly because the reaction only takes place at a constant temperature. We aimed to develop a LAMP assay for rapid detection of Streptococcus pneumoniae serotypes in nasopharynx swab samples. The LAMP primers were designed using a conserved region of the lytA gene. An incubation time range of 30 to 60 minutes was studied to optimize the LAMP reaction. The real-time fluorescence intensity was monitored during the amplification reaction. Clinical nasopharynx swab samples identified as Streptococcus pneumoniae and their serotypes were tested to evaluate the performance of LAMP. To investigate the specificity of the LAMP, Streptococcus species samples and non-Streptococcus species samples were analyzed. In conclusion, the optimized LAMP assay is capable of detecting Streptococcus pneumoniae and its serotypes in nasopharynx swab samples.