Prospective Study of the Relative Abundance of Antimicrobial Resistance Genes in Escherichia coli O157:H7 Obtained from Chicken Carcasses from Local Markets in Lima, Peru

<b>Objective:</b> This study addresses antimicrobial resistance (AMR), a growing public health threat, by evaluating the role of chicken carcasses as possible vehicle for the spread of <i>Escherichia coli</i> O157:H7 and antimicrobial resistance genes (ARGs), with the aim of analyzing the association between bacterial load and the relative abundance of ARGs in samples obtained from an open and an enclosed market in Lima, Peru. <b>Methods:</b> SYBR Green qPCR was used to analyze 28 chicken carcasses from two local markets in the Lima metropolitan area (Enclosed market <i>n</i> = 13, and Open Market <i>n</i> = 15), detecting <i>Escherichia coli</i> O157:H7 and ARGs like <i>bla_CTX-M</i>, <i>bla_TEM</i>, and <i>strA</i>. <b>Results:</b> The bacterial load was higher in the enclosed market (5.062 log CFU/mL) than in the open market (3.875 log CFU/mL). <i>E. coli</i> O157:H7 was detected in 76.9% and 86.6% of samples, with average loads of 1.676 and 1.251 log CFU/mL, respectively. The relative abundance of <i>bla_CTX-M</i> and <i>bla_TEM</i> showed greater dispersion in the open market, whereas <i>strA</i> was more homogeneous in both markets. Significant positive correlation was found between <i>E. coli</i> load and ARGs abundance, stronger in the enclosed market (r = 0.904-0.945) and moderate to high in the open market (r = 0.794-0.920). <b>Conclusions:</b> The results demonstrate a significant correlation between <i>E. coli</i> O157:H7 load and ARGs, highlighting the need for a comprehensive approach within the framework of the "OneHealth" initiative.