Multiplex PCR amplification
Primer-pair sequences (bla-SHV.SE/AS; TEM-
164.SE and TEM-165.AS; universal CTX-M-U1/U2)
used in the multiplex PCR assay, origin and expected
PCR amplicon sizes are given in Table 2. Initially, a
PCR annealing temperature gradient was performed
and all subsequent multiplex PCR reactions were carried
out using 1 ml DNA solution, Qiagen HotStarTaq
Master Mix (Qiagen Nr. 203445) and 10 pmol of each
gene-specific primer in a final volume of 25 ml. PCR
amplification conditions were as follows: initial denaturation
step at 95 æC for 15 min; 30 cycles of denaturation
at 94 æC for 30 s, annealing at 60 æC for 30 s, extension
at 72 æC for 2 min, followed by a final extension
step at 72 æC for 10 min.