Molecular characterization of endemic salmonella infections ... - Evira

to replace phage typing in the future (Lan et al 2007). In a longitudinal study of 18 pig farms over a
three-year period, AFLP differentiated between distinct clones within DT104. It was also more
discriminatory than the PFGE and REP-PCR methods (Gebreyes et al 2006). In a study on S.
Typhimurium comparing three PCR-based methods, AFLP, PCR-phage typing and detection of
integrons, the highest discriminatory power was achieved with the use of AFLP (Mikasová et al
2005).
A single-enzyme approach (SAFLP) based on the use of only one restriction enzyme with a single
adapter was used to fingerprint 30 strains of S. enterica belonging to 14 different serotypes.
SAFLP was able to differentiate between the serotypes and also to differentiate between both the
phage types and between individual strains. Another advantage of SAFLP, besides its specifity, is
its reproducibility and speed. It is faster to perform than many other DNA-based methods (Peters
and Threlfall 2001). Fluorescent AFLP (FAFLP) uses fluorescent dye-labeled PCR primers. It may
provide important insights into the microepidemiology of different Salmonella serovars (Lawson et
al 2004). FAFLP was applied to 46 isolates of S. Typhimurium, comprising nine phage types. This
method is highly discriminatory and was capable of grouping most serovar Typhimurium isolates
according to phage type (Hu et al 2002). In a study by Tamada et al (2001), S. Typhimurium
strains were analysed by both fluorescent AFLP and PFGE; both methods were equally useful for
epidemiological typing, though no data on the phage type was given. In a study on 97 strains of S.
enterica subsp. enterica, FAFLP had a discriminatory capacity equal to that of PFGE (Lindstedt et
al 2000). In another study, FAFLP showed a greater ability than PFGE to discriminate between
outbreak-associated and epidemiologically unrelated isolates of S. Typhimurium DT126. However,
neither method was sufficiently sensitive to separate all epidemiologically unrelated DT126 isolates
from the outbreak isolates (Ross and Heuzenroeder 2005a). When investigating an outbreak of
multiresistant S. Typhimurium DT104, the genotype of the outbreak-associated strain could not be
differentiated from that found in most multiresistant DT104 isolates by either PFGE or fluorescent
AFLP (Lawson et al 2004). When analysing 110 isolates and 25 serotypes of S. enterica
subspecies enterica with multilocus sequence typing (MLST), PFGE and AFLP, it was concluded
that with the MLST scheme used, PFGE and AFLP had a higher discriminatory power. It was
suggested that AFLP should be used for local outbreak investigations, as the interpretation of the
AFLP fingerprints was very subjective and dependent on the person performing both the analysis
and the interpretation (Torpdahl et al 2005).
IS200-PCR
IS200-PCR is a procedure for the amplification of DNA fragments with outward-facing primers
complementary to each end of the insertion sequence IS200. The method was evaluated and
compared with other molecular methods such as ribotyping, RAPD analysis, ERIC-PCR and PCR
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