FIPS Conference (June 2011) – developing technologies
Much interesting work is going on but nothing was described that is likely to radically change current practice in the immediate future. The meeting embraced the principle of Water Safety Plans as the first line of defence for public health with traditional microbiological monitoring only as a confirmatory tool. E.coli and enterococci remain the indicators of choice but Bacteroidetes are the mainstay of developing molecular technologies, being more numerous in faeces and having a number of host-specific species and strains.
Quantitative microbial risk assessment
A modeling tool using environmental and epidemiological data to assess and inform risk management therefore not an exact science. Useful in setting standards and for assessing risk of organisms such as Legionella for which indicators do not exist.
Polymerase chain reaction (PCR)
Genetic method detecting DNA or RNA specific to microbial species. Now a largely automated methodology. Offers great potential as technology develops. Can be used to detect pathogens as well as indicators and can be made quantitative (qPCR) and also may be modified to detect only living organisms. Being used as a rapid confirmation method for coliforms giving results in 2 hours. Useful in source detection using nucleic acid from Bacteroidetes species selected as specific to human or other animals. Being used for investigating and modeling bathing waters.
Used for many years in research as surrogate indicators for enteric viruses but with limitations as unable to distinguish whether from human or animal sources. Now able to use PCR to distinguish human and animal source phages.
Fluorescence in-situ hybridization (FISH)
Use fluorescent labeled nucleic acid probes to detect specific nucleic acid sequences in chosen indicator or pathogen. Detects both live and dead organisms but can use with short pre-incubation. Can be used in conjunction with flow cytometry to detect indicators or pathogens directly in-situ.
Now the virus of choice for monitoring and researching bathing waters rather that enteroviruses.
Biofilms in water systems.
Remain a source of concern as they may harbour and protect indicators and pathogens.
Other issues raised.
Evidence is emerging of environmental strains of E.coli. able to multiply outside the mammalian gut.
The significance of viable but non–culturable organisms (VBNC) remains a subject of debate.