Introduction: Serratia marcescens is known to cause outbreaks in hospitals and is considered opportunistic. The World Health Organization stressed the need for new antibiotics to treat this bacterium in 2017 due to the bacterium's resistance to various antibiotics, which has made it challenging to treat. Rapid detection methods, such as isothermal nucleic acid techniques, have emerged as a reliable and fast way to identify bacteria. These methods can be performed at a consistent temperature and could aid in controlling the spread of S. marcescens and ultimately reduce its impact on public health. In this study, an isothermal amplification method was developed to detect S. marcescens.
Methods: To target a specific gene in the whole genome of S. marcescens, specific primers were designed. Nucleic acids from S. marcescens and eleven other related bacteria were extracted using the boiling method. The isothermal amplification technique was used to amplify the targeted gene, and hydroxy naphthol blue was added for colorimetric detection of the products. To ensure the accuracy of the study, DNA from eleven other related bacteria and S. marcescens was used. The sensitivity was evaluated using samples with different dilutions of DNA from S. marcescens.
Results: The isothermal method that was developed can detect the existence of S. marcescens DNA by amplifying the targeted gene within just 20 minutes at a temperature of 65°C. A positive sample containing S. marcescens DNA exhibited a clear sky-blue color change, whereas negative samples that contained DNA from eleven other bacteria changed to purple and dark blue. The specificity of the test was found to be 100% and the sensitivity was 94×10-3 ng/mL.
Conclusion: The initial report on the implementation of the developed isothermal method for detecting S. marcescens showed high speed, high sensitivity and precision to detect the bacterium at the point-of-care level. This method has the potential for detecting and preventing S. marcescens outbreaks at an early stage.