Detection of blaCTX-M-type genes in complex class 1 integrons carried by Enterobacteriaceae isolated from retail chicken meat in Brazil

• Presence of ESBL-producing Enterobacteriaceae in chicken meat has been investigated.
• Identification of CTX-M-2- and CTX-M-8-producing Enterobacteriaceae in chicken meat is highlighted.
• Presence of blaCTX-M-2 gene into complex class 1 integron following ISCR1 element was confirmed.
• Potential food transmission of CTX-M producing Enterobacteriaceae has been discussed.

CTX-M-type extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae have been increasingly identified in humans and animals, and their potential transmission by contaminated food has been highlighted. In this study, we report for the first time the isolation of multidrug-resistant (MDR) Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis strains harboring blaCTXM-2 or blaCTXM-8 gene variants in chicken meat sold in markets in southeast Brazil. In this regard, the genetic environment of the blaCTX-M-2 gene is composed of a complex class 1 integron and an ISCR1-associated sequence with dfr and/or aadA gene cassettes located within the variable region. In summary, chicken meat may be a reservoir of MDR Enterobacteriaceae harboring blaCTX-M-type genes, which is a public health concern.