DEVELOPMENT AND APPLICATION OF A LOOP- MEDIATED ISOTHERMAL AMPLIFICATION ( LAMP) METHOD FOR RAPID AND SENSITIVE DETECTION OF ENTEROCOCCUS FAECALIS IN DRINKING WATER

The genus Enterococcus comprises opportunistic pathogens such as Enterococcus faecalis and E.faecium, and is used to assess water quality. E.faecalis has become prominent in recent decades because of its ability to develop resistance to various antibiotics. A loop-mediated isothermal amplification (LAMP) method for rapid and sensitive detection of E.faecalis in drinking water samples was developed and applied in this study. Four primers were specifically designed by targeting the mtlf gene. The mtlf-based LAMP assay was able to specifically detect all of 54 E.faecalis isolates without amplification of 36 nontarget bacterial strains. The detection limit was 74cfu/mL in pure culture, which was as high as 100-fold more sensitive than that of the groES-polymerase chain reaction (PCR) method. When applied to artificially contaminated water, the LAMP assay was able to detect E.faecalis with low concentration (3.2cfu/250mL), after 10h enrichment culture. In the case of drinking water samples, 7.14% (7/98) of the samples were found to be positive by LAMP, which was in accordance with the results from the GB/T 8538-2008 method. The LAMP assay established in this study may provide a candidate method for rapid and sensitive detection of E.faecalis in drinking water samples. Practical ApplicationsE.faecalis contamination in drinking water source and drinking water has been reported. In developing countries, such as China, the LAMP assay may prove as a useful tool for rapid assessment of water quality as it is more cost-effective, simple and sensitive than PCR.