Microbial quality of drinking water is monitored by indicator bacteria including fecal E. coli. Traditional enumeration methods to detect E. coli require 1-2 days to produce results. Gómez et al. (2025) were able to reliably detect E. coli in drinking water within six hours by utilizing RNA marker detection method in EU laboratories. Rapid method allows timely interventions in contamination events and can help to prevent waterborne outbreaks.
E. coli are common bacteria present in the guts of warm-blooded animals. It does not survive outside the gut for long periods of time, which makes it a good indicator of recent fecal contamination. Fast detection of fecal contamination in the drinking water distribution systems is important in prevention of infections caused by fecal pathogens, such as norovirus, campylobacter or salmonella. RNA marker analysis is a valid tool to detect living bacteria from water, as RNA degrades quickly when the cell dies. Living and active cell needs RNA for all its’ functions and produces it actively. Abundance of RNA in active cells enables the detection of RNA marker.
RNA marker analysis was validated in two interlaboratory studies with 19 laboratories from different EU countries. Laboratories were able to follow the provided procedure, although not all were familiar with the method. However, results delivered on the second round were of better quality, highlighting the importance of practice when introducing new methods. The RNA marker analysis showed 91% sensitivity, which is slightly lower in comparison to the 97% sensitivity of the traditional method.
Although the rapid method was slightly less sensitive than the traditional method, it provides a valid tool for drinking water monitoring. Quicker method enables quick reactions to contamination events and helps to prevent waterborne outbreaks. With training and practical experience, the sensitivity of the rapid method can be increased.
Reference:
Gómez, L., Brandão, J., Navarro, A., Martines, A., Sanseverino, I., Porcel-Rodríguez, E., Marinov, D., Ableitner, O., Allerberger, F., Atsma, A., Briancesco, R., Cenov, A., Cíchová, M., Coccia, A. M., Della Libera, S., De Maeyer, K., Jan de Vries, H., Elsinga, G., Heijnen, L., . . . Lettieri, T. (2025). Application of a real-time reverse transcription polymerase chain reaction for rapid detection of Escherichia coli in drinking water: an EU representative study. Environmental Research, 279, 121786. https://doi.org/10.1016/j.envres.2025.121786