Applications of Emerging Technologies in the Drinking Water Sector - Waterborne Pathogens: Detection Methods and Applications - page 356

detect particular bacteria such as certain substrates that confer a particu-
lar color in growing colonies and therefore can be detected with optical
methods. 47
3. Immunology-based methods —These methods provide powerful analyti-
cal tools. For example “immunomagnetic separation” can be used to
capture and extract a pathogen by placing an antibody coated in mag-
netic beads into the bacterial suspension holding it. 47 Drawbacks of this
method include the fact that it is time-consuming and it may not be as
sensitive in detecting pathogens as PCR methods. 49
Existing technology in the UK water industry for monitoring and detect-
ing pathogens does have shortcomings in that the majority of the work is
time-consuming and labor-intensive, it is not always entirely 100% reliable,
and it is costly. For example, identifying Cryptosporidium in water supplies
takes UK water companies anywhere between 5 and 6h for a high-risk,
priority sample and up to 3 days for a low-risk one. Furthermore, the cost
of one Cryptosporidium sample is between around £70 and £110 for UK
companies, and with some companies taking out almost up to 500 samples
per week, this is a very substantial cost.
Although traditional approaches can be deemed sufficiently sensitive,
their slow pace and the amount of effort required to undertake them means
there is a need to look for potential alternate options. One new approach
being considered and studied is the use of “biosensors”. This involves the
use of biological or biologically derived material to detect pathogens. 47
Biosensor technology has the ability to combine a variety of molecules into
a single chip and is able to monitor water in real-time. 50
“DNA microarrays” are another emerging technology that uses special-
ized biosensors that utilize special oligonucleotides to screen nucleotide
mixtures. However, this method is likely to face challenges in that the relative
abundance of pathogens is likely to vary, making isolation more difficult.
Furthermore, many authors argue there needs to be a move toward “molecu-
lar” methods for detecting pathogens. There is currently an emerging market
for more sophisticated gene technologies for pathogen detection; however,
these potential changes would require an increase of skilled staff and the sys-
tem would have to be both flexible and reproducible to allow it to be used in
different countries and locations. 51 Despite this, the advantages are numer-
ous; molecular methods have enhanced sensitivity and an increased ability to
distinguish genotypes. 50 These techniques provide effective analytical tools
to detect pathogens, including new emergent strains, and they can be used to
evaluate the microbiological quality of water. 62