LIMITATIONS OF CONVENTIONAL LABORATORY TESTS: Although
conventional bacterial testing methods are sensitive, inexpensive and contain
qualitative and quantitative information of the microorganisms present in a
food sample, they are often very time consuming and require extensive
microbiological trainings. Conventional bacteria testing involve five steps:
pre-enrichment, selective-enrichment, selective plating, biochemical tests
and serological tests. The concept behind these steps is to isolate the targeted
microorganisms from other organic and non organic substances and then grow
them in culture medium into visible colonies for detection which usually
takes 5 to 7 days. Storage of food for seven days for
laboratory results costs food industry millions of dollars. In many cases when result of a laboratory
test is ready, food products are in suppliers’ warehouses or on supermarkets’
shelves. In addition, preparation of culture medium, incubation of plates, biochemical
tests and immunodiagnostic test make these methods labor intensive. Automated
systems have enhanced the detection of microorganisms. These automated
systems perform the same test as conventional procedures but results are
determined within few hours with minimal human interference. The
disadvantages of automated devices are that they require pure cultures and
operate with large and expensive equipments. Such disadvantages have limited
the used of automated devices to hospital laboratories for human clinical
applications. Immunofluorescence
and enzyme-linked immunosorbent assays (ELISAs) are immno-diagnostic tests
that use antibody/antigen binding complex to identify microorganisms Although
these tests are quick with high selectivity and specificity, they require at
least
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