to extended-spectrum cephalosporins and fluoroquinolones
among Thai isolates might have been underestimated, since some
of the isolates included in the study were selected based on the
results of a disk diffusion screening, which was not reliable for the
detection of extended-spectrum cephalosporin and fluoroquinolone
resistance. A subset of isolates that were defined as intermediately
resistant to extended-spectrum cephalosporins and were
included in the study as representative of the regional zones and
not as potential extended-spectrum cephalosporinase producers
were shown to harbor extended-spectrum cephalosporinaseencoding
genes, and the detection of PMQR genes by disk diffusion
is notoriously difficult (8).
At the genotypic level, we observed both broad genetic diversity
among the Salmonella serovar Stanley isolates from Thailand