PCR and sequencing of the 24 extended-spectrum cephalosporin-resistant isolates showed that 23 (96%) isolates harbored a blaCMY-2 gene and one (4%) isolate harbored a blaCTX-M-15 gene, thus showing an exact correlation between the observed phenotype and genotype (Table 2). In Thailand, the overall prevalence of extended-spectrum cephalosporin-resistant isolates was 10.4% (20 resistant out of 193 tested)