Antibiotics are successful drugs used in human and animal therapy; however, they must be considered as environmental pollutants. This study aims to isolate and characterize the extended-spectrum β-lactamase (ESBL) producing Escherichia coli soil from Azores Archipelago subjected to livestock agricultural practices. Twenty-four soil samples were collected from three different pasture systems with different number of cattle heads, and from a control site. Antibiotic susceptibility method was performed by Kirby–Bauer disk diffusion method against 16 antibiotics, and the presence of genes encoding lactamases, antimicrobial resistance genes, virulence factors, and phylogenetic groups was determined by polymerase chain reaction (PCR). Nine ESBLs were recovered from the three grazing sites, and all isolates presented the beta-lactamase genes bla_CTX-M-3 and bla_SHV. E. coli isolates were resistance to tetracycline and streptomycin and harbored the tetB, strA, and strB genes. One isolate also showed resistance to sulfonamides, and the genes sul1 and sul2 were detected. The isolates were grouped into the following phylogenic groups: B1 (n = 6), D (n = 2), and A (n = 1). The presence of antibiotics and resistance genes in soils may be the source to the development of antimicrobial resistance, which may have negative consequences in human and animal health.

抗生素是用于人类和动物治疗的成功药物；但是，必须将其视为环境污染物。这项研究旨在分离和表征产生大范围β-内酰胺酶（ESBL）的大肠杆菌来自亚速尔群岛的土壤经过了畜牧业耕作。从具有不同数量牛头的三种不同的牧场系统以及一个对照地点收集了二十四个土壤样品。用Kirby-Bauer纸片扩散法对16种抗生素进行药敏试验，并通过聚合酶链反应（PCR）确定编码内酰胺酶，抗菌素耐药基因，致病因子和系统发生基团的基因的存在。从三个放牧地点回收了9个ESBL，所有分离株均呈递β-内酰胺酶基因bla _CTX-M-3和bla _SHV。大肠杆菌分离株对四环素和链霉素具有抗性，并带有tetB，str A和str B基因。一种分离物还显示出对磺酰胺的抗性，并且检测到基因sul 1和sul 2。分离株分为以下系统发育组：B1（n  = 6），D（n  = 2）和A（n  = 1）。土壤中抗生素和抗性基因的存在可能是产生抗药性的根源，这可能对人类和动物健康产生负面影响。