Antibiotic Susceptibility Profiles and Resistance Mechanisms to β-Lactams and Polymyxins of Escherichia coli from Broilers Raised under Intensive and Extensive Production Systems

Abstract

The intensive and extensive broiler production systems imply different veterinary interventions, including the use of antimicrobials. This study aimed to compare the antimicrobial susceptibility profiles of Escherichia coli isolated from both systems, characterize resistance mechanisms to β-lactams and polymyxins, and identify genetic elements such as integrons. E. coli isolates recovered from broiler cecal samples were assayed for antimicrobial susceptibility through the broth microdilution technique. The molecular characterization of acquired resistance mechanisms to β-lactams and colistin and the detection of integrons was performed by a multiplex PCR. For most antibiotics tested, the prevalence of reduced susceptibility is higher in commensal and extended-spectrum β-lactamases (ESBL)/AmpC producers from broilers raised in the intensive system, compared with those raised under extensive conditions. SHV-12 was the most common ESBL enzyme found in both production systems. Other ESBL variants such as CTX-M-1, CTX-M-55, CTX-M-14, CTX-M-32, CTX-M-9, TEM-52, and plasmid-encoded AmpC enzyme CMY-2 were also present. MCR-1 was identified in a colistin-resistant isolate from broilers raised under the intensive system. This study highlights the differences in E. coli antibiotic susceptibility from both production types and emphasizes that a great deal of work remains to decrease consumption and antimicrobial resistance levels.

Antibiotic Resistance among Gastrointestinal Bacteria in Broilers: A Review Focused on Enterococcus spp. and Escherichia coli

“…Avoparcin, a glycopeptide antibiotic analog of vancomycin, was introduced as a feed additive in chicken feed in 1987, and, even though it was banned from the EU in 1997, the development of vancomycin-resistant Enterococci might have been potentiated by its use as a feed additive in livestock [ 38 , 39 , 40 , 41 ]. Furthermore, β-lactams are among the most used classes of antibiotics both in humans and animals, and an increasing trend of gastrointestinal colonization by extended-spectrum β-lactamase (ESBL) producing bacteria has been observed in commercial poultry farms and humans [ 42 , 43 ]. ESBL-producing bacteria are often reported among broilers, and the acquisition of ESBL genes among gastrointestinal microflora may play an important role in the spread of multidrug-resistant bacteria among humans, animals, and the environment via the food chain [ 44 , 45 , 46 ].…”

Atividade antimicrobiana produzida por fungos filamentosos isolados das águas do Baixo Rio Tapajós, Pará, Brasil

“…Em 1929, Alexander Fleming fez uma das mais promissoras descobertas na área da saúde, uma potente substância antibiótica proveniente do fungo Penicillium notatum Westling, nomeada de Penicilina [1,2]. Desde então, os antibióticos naturais são comumente utilizados contra infecções causadas por micro-organismos, tanto em organismos humanos, demais animais e plantas [3][4][5]. Na área biotecnológica, os antibióticos se destacam por sua importância econômica e sua variedade [6] na medicina moderna, a antibioticoterapia se tornou essencial, porém, seu uso indiscriminado fez emergir um alerta relacionado à resistência microbiana aos fármacos, através de fatores como sua prescrição inadequada ou automedicação [7].…”