Rapid Detection of Listeria monocytogenes Strains Isolated from Clinical and Non-Clinical Samples by Loop-Mediated Isothermal Amplification Method (LAMP)

Diagnosis of Listeria monocytogenes infections is critical for epidemiological study and prevention of diseases. This study aimed at identifying L. monocytogenes isolates, using Loop-Mediated Isothermal Amplification Method (LAMP). Listeria strains were obtained from clinical and seafood specimen. All listeria strains were identified by standard microbiological and biochemical tests. The LAMP assay was performed at 65°C with a detection limit of 2.5 ng/μl for 46 min. Specific primers for the hylA gene were used to identify L. monocytogenes. The specificity of the assay was assessed, using DNA from L. monocytogenes ATCC 7644 and L. ivanovii ATCC 19119 and non-Listeria strains. Sensitivity of the LAMP assay was compared with polymerase chain reaction (PCR) method. Amplification LAMP products were visualized via calcein and manganous ions as well as agarose gel electrophoresis. A total of 191 samples were obtained, including clinical and food samples. Then, 21 (10.9%) isolates were recovered from specimens. The LAMP results showed high sensitivity (97.2%) and specificity (100 %). The LAMP assay was higher sensitive than of the PCR assay. This data showed that this method could be used as a sensitive, rapid, and simple identification tool for diagnosis of L. monocytogenes isolates and it may be suitable for epidemiological study plans.