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Chapter 1
Multi Locus Sequence Typing schemes (MLST) are used to identify unique
DNA sequences or alleles from a portion of housekeeping genes of the
organism under examination. The unique DNA sequences are assigned a
unique sequence type number which can be compared to a database of
assigned sequence types of the organism under examination. This method
has been used to identify alteration in housekeeping genes and to
determine the order and sequence of evolution within a species over time
[26].
Typing methods have recently progressed to the level where multiple
strains can be analysed to identify a large number of single nucleotide
polymorphism (SNP) through whole genome sequence analysis. This
method can differentiate between strains within the same serotype, with a
similar pulse field profile and phage type based on the sequence type of
the strain [27].
1.10. Zoonotic Infection - transmission from farm to fork
Salmonella adherence to epithelial cells and the formation of intricate
biofilm communities may play an important role in the carriage of the
organism in animals [28]. Animals can be asymptomatic carriers of
Salmonella in their intestinal tract therefore hygiene precautions are
always required when handling carcasses and processing raw meat.
Contamination of food such as meat can stem from poor handling of raw
meat or cross contamination originating from the intestinal content of
livestock.
Once surfaces have become colonized with Salmonella, the pathogen can
continue to contaminate food and food processing surfaces further down
the processing line. Barker and colleagues demonstrated that during the
processing and handling of contaminated raw meat, work surfaces can
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