Bays, inlets and rivers are under increasing pressure from urbanisation, population growth and climate change to continue to properly serve their communities. In coastal and inland regions around the world, fecal contamination remains the primary cause of closure for recreational use.
Researchers from Monash University used Thermo Fisher Scientific’s TECTAtm B16 to study and sample Melbourne’s recreational waters.
There are many recreational waters across Melbourne that are often under scrutiny for their pathogen levels, in particular the Yarra River and Port Phillip Bay. To begin to combat the effects of rapid urbanisation and population growth on these waters, a study by Monash University collected 233 samples from Melbourne waters during the 2014–2015 swimming season for analysis by four methods.
Limitations of traditional techniques
Substrate Culture testing techniques, such as the IDEXX methods, have commonly been used to quantify Total Coliform and E.coli levels because of their perceived low price, familiarity with lab technicians and for providing evidence that links such levels to human illness.
Over time they have become the effective industry standard in Melbourne, Australia. However, these methods have at least three drawbacks:
- They take a minimum 18 hours to complete, meaning risks are slow to be reported back to the community
- Lab personnel are required to interpret results the following day, making Friday samples problematic due to staffing issues
- They rely on visual interpretation of colour or fluorescence increasing the risk of user bias and systematic or arbitrary error
Fast and simple solution
To combat and even eliminate the limitations of traditional methods, Monash University utilised Thermo Fisher Scientific’s TECTA B16 automated process, which effectively removed all human error while providing more accurate and objective test results (regardless of how turbid the water); all in a fraction of the time required by traditional cell-culture techniques.
Unlike IDEXX and other traditional methods, no time was needed to interpret results since the TECTA B16 continuously monitored enzyme activity through fluorescent markers. Results were automatically translated by the instrument into a concentration of colony forming unit per 100mL (cfu/100mL) for Total Coliforms and E.coli. These reports were immediately sent by email from the TECTA B16 to the operators.
The mean detection time by the TECTA B16 method was 13 hours for total coliforms and 12 hours for E. coli, against the 24 hours necessary for both IDEXX methods; significant time savings that provide decision makers essential early warnings, meaning better safety and true cost reductions for the community.
As for accuracy, TECTA B16 CFU/100mL results were correlated with IDEXX MPN/100mL results for all recreational water sites studied. The IDEXX method was limited to an upper detection limit of 20820 MPN/100mL, while the TECTA B16 method never reached its upper detection limit.
The results of TECTA B16 vs IDEXX followed a 1:1 relationship, showing that neither method consistently over or underestimated the sample concentrations with respect to one another.
Costs of consumables for the TECTA B16 tests were found to be equivalent to those for IDEXX. Yet, with sample processing times considered, TECTA B16 was found to be 80 per cent of the cost of IDEXX.
Researchers found that the TECTA B16 system was very easy to use and did not require extensive training typical of other methods. The sample handling steps were extremely simple, limited to just adding water to the test cartridge that already contained all necessary ingredients for the test. The TECTA cartridges were then easily loaded into the TECTA B16 instrument.
They concluded that the TECTA B16 was by far the fastest method in terms of sample handling, needing only five minutes per day.
Lauren Butler is the assistant editor for Utility Magazine. She’s based in Melbourne, Australia.