Sample Processing - Waterborne Pathogens: Detection Methods and Applications - page 101

negative control (PBS). During the subsequent microscopic analysis, the
ColorSeed (oo)cysts will fluoresce in green under FITC conditions and
in red under Texas Red conditions and thus are easily differentiated from
naturally occurring (oo)cysts. The fraction of red (oo)cysts recovery shows
the efficiency in the part of the method in which they were included.
4.7. SUMMARY
This chapter has reviewed a stage critical to the detection of water-
borne pathogens, namely that of sample preparation. The techniques
described in this Chapter are all critical to the overall success of the detec-
tion technologies described in the next Chapters. Many of the methods
in Chapters 5-8 operate with small sample volumes and require purified
samples for success. In this summary, we provide a review of the sample pro-
cessing techniques considering each class of pathogen in turn and finish by
drawing conclusions upon the existing state of the art in sample preparation
and expected future directions.
Sampling and analytical procedures for the microbiological analysis of
water are well documented. A variety of techniques have been described for
the recovery of viruses, bacteria, and parasites from water, each with their
own advantages and disadvantages as the physicochemical quality of the
water, including but not limited to the pH, conductivity, turbidity, presence of
particulate matter and organic acids can all affect the efficiency of recovery of
microorganisms. It is important to acknowledge that no single method may
be recognized universally as superior: efficiency, constancy of performance,
robustness, cost, and complexity are all factors to be considered for each
method, and performance characteristics must be continually monitored.
Different methods of sample processing are also likely to be required
depending upon the type of monitoring undertaken. For operational moni-
toring the main requirement is likely to be rapid detection and, therefore,
simple quick methods are preferable. During investigative monitoring of
an outbreak pathogens may be present in higher numbers such that large
samples and high recoveries rates are less critical, and it is more important to
ensure rapid and efficient removal of interferents to enable accurate detailed
information on pathogen species being obtained. Finally, for surveillance
monitoring high recovery rates are likely to be a key requirement in order
to detect potentially low numbers of pathogens.
A vision of networked in situ sensors is a particular challenge for water-
borne pathogen monitoring, and often sample processing would be required