Quick online detection of enterococci with the BACTcontrol sensor

The overall objective of this study was to further develop the enterococci assay on the BACTcontrol and evaluate the applicability for analysis of drinking water and surface water (bathing water, drinking water intake) in a laboratory and on-site setting.
The study first optimized the enterococci assay on the BACTcontrol (laboratory studies at KWR and HWL) to improve the detection limit and the reproducibility of the relation between the BACTcontrol signal and culturable enterococci concentrations in water samples. Subsequently, the BACTcontrol enterococci assay was applied in drinking water settings (Vitens Laboratory and HWL) and two recreational water settings (Hoogheemraadschap van Delfland). The results for the performance characteristics tested in this study are: User experience: the users indicated that the BACTcontrol enterococci assay is easy and can be run at laboratory and semi-continuous mode, but also highlighted technical limitations that hamper semi-continuous operation and low maintenance. Several recommendations were made for improvements of the BACTcontrol system operation and maintenance based on the users’ experience.
Time-to-result: a key characteristic of the BACTcontrol enterococci assay is the short time-to-result: the results of the BACTcontrol are available within 2 hours after sampling, while the culture method takes one to two days.
Background signal (noise): the background signal of the BACTcontrol when monitoring drinking water in an on-line setting is low (0 – 4 pmol/min), but can also be high. It is not clear what determines the difference in the background level between drinking water sites. Analyzing the cause of the differences could provide information about what water quality parameters impact the BACTcontrol enterococci assay signal. Linearity: the BACTcontrol enterococci assay is linear when different volumes of the same sample are tested.