As STEC present below the detection limit could
constitute a risk (Loge et al. 2002), the sensitivity may be
increased by concentrating the water samples prior to
analysis. Alternatively, DPCR could be performed on an
enrichment culture provided that the cells are culturable. In
this case, DPCR would provide a means to detect E. coli
O157:H7 in an enrichment culture that would be faster than
subculture on selective and differential media. The demonstration
that a 10-fold dilution of a culture grown in EC
broth (Difco, Detroit, MI, USA) is sufficient to relieve PCR
inhibition (not shown) suggests that DPCR would provide a
rapid means to confirm the presence of STEC in enrichment
cultures. With optimized primer design and PCR conditions,
DPCR could be used to detect other virulence genes
of E. coli O157:H7 and distinguish E. coli O157:H7 from
other STEC.