Conclusions - Waterborne Pathogens: Detection Methods and Applications - page 369

automated approaches enable rapid, on-site detection with a reduction in
technician time, disadvantages such as the need for expensive reagents and
the lack of information on species and viability remain. Spectroscopic tech-
niques, including infrared and Raman spectroscopy avoiding the use of any
labels have an immediate advantage in terms of simplified sample prepara-
tion and reduced reagent cost. “Fingerprint” spectra from single cells have
been recorded, thus offering the opportunity of species and viability testing
to the single organism level. However, more evidence is required to deter-
mine spectral variability to improve understanding of the sensitivity and
robustness of this type of technique. Additionally, a spectral library is needed
characterizing the results of numerous pathogen screens, thus enabling
identification of an unknown sample.
Chapter 6 introduced electrochemical and electrical methods of detec-
tion of waterborne pathogens. After an introduction to the various tech-
nologies, the chapter discussed the advantages and gains to be expected
from miniaturization and integration of these types of systems. Electrical
approaches have been applied to viruses, bacteria, and protozoa, though
most literature reports are not directly concerned with waterborne patho-
gens. Impedance and dielectrophoresis for protozoan detection appears to
be the most common waterborne pathogen application. These methods
offer the advantage of viability discrimination, and could potentially be
applied at a single cell level. The main concern relating to this type of tech-
nology is whether reproducibility can be assured to enable scale-up from
laboratory demonstrations to real world applications.
Chapter 7 presented a range of biosensor technologies which have been
applied to the detection of waterborne pathogens. All main types of bio-
sensor transduction approaches, e.g. optical, electrical, and mass-sensitive,
have been studied. Bacterial biosensors have been the most well researched
area, with limits of detection generally on the order of 10 2 cells mL −1 . Pa r -
ticularly, E. coli is often employed as the test organism for new biosensor
approaches. Optical detection schemes have proved most popular for bacte-
ria, and the same is true for viruses. Biosensors for viruses are a more recent
area of research, with fewer examples found. However, protozoan biosen-
sors are fairly well-represented in the research literature, with mass-sensitive
approaches dominating, possibly due to their greater size and mass, relative
to viruses and bacteria.
Advantages of biosensors are speed and the potential for portability.
One challenge is that the limits of detection presented by the biosensors
remain relatively high for the application to waterborne pathogens and often