Abstract

DNA microarray was developed for detection of up to 90 antibiotic resistance genes in Escherichia coli by hybridization. Each antibiotic resistance gene was represented by two specific oligonucleotides chosen from consensus sequences of gene families. A total of 203 oligonucleotides (50-100 base) were spotted onto the microarray. The sequence identity of each gene was compared with GenBank sequen-ces, biotin was used as the positive control and 16s rRNA as orientation. Of the 40 E. coli isolates analyzed in this study, 37 were identified as having, at least, one antibiotic resistance gene. Among the different antibiotic resistance genes detected, bla-CMY-2 and strA were the most prevalent occurring in 28 (70%) of the isolates, respectively. Other common genes included were TEM1 11(27.5%), Sul2 14 (35%) and TetA 21(52.5%). The microarray genotyping corresponded with the phenotype of the strains. The disposable microarray presents the advantage of rapidly screening bacteria for the pre-sence of known antibiotic resistance genes. This technology has a large potential for applications in basic research, food safety, and surveillance programs for antimicrobial resistance.

Key words: DNA microarray, antibiotic resistance, Escherichia coli.