title: Antimicrobial susceptibility and phylotyping profile of pathogenic Escherichia coli and Salmonella enterica isolates from calves and pigs in Minas Gerais, Brazil.
abstract: The aims of the present study were to determine (i) the profiles of phylogroup and (ii) the antimicrobial susceptibility of pathogenic Escherichia coli strains isolated from calves, and of Salmonella spp. strains isolated from calves and pigs in Minas Gerais State, Brazil. Sixty-one pathogenic E. coli strains and Salmonella spp. (n = 24) strains isolated from fecal samples of calves and Salmonella spp. (n = 39) strains previously isolated from fecal samples of growing/finishing pigs were tested. The minimum inhibitory concentration (MIC) using the agar dilution method was determined for nalidixic acid, amikacin, amoxicillin, ampicillin, cefoxitin, norfloxacin, gentamicin, tetracycline, and trimethoprim-sulfamethoxazole. All E. coli isolates were susceptible to amikacin. Tetracycline was the antimicrobial that presented the higher frequency of resistance among E. coli strains, followed by ampicillin, trimethoprim-sulfamethoxazole, amoxicillin, nalidixic acid, norfloxacin, gentamicin, and cefoxitin. E. coli (n = 61) strains isolated from calves belonged to different phylogroup namely, phylogroup A (n = 26), phylogroup B1 (n = 31), phylogroup E (n = 3), and phylogroup F (n = 1). Phylogroups B2, C, and D were not identified among the E. coli in the present study. All Salmonella spp. (n = 24) strains isolated from fecal samples of calves were susceptible to amikacin, amoxicillin, ampicillin, norfloxacin, gentamicin, tetracycline, and trimethoprim-sulfamethoxazole. Resistance to nalidixic acid and cefoxitin was detected in 16.66 and 8.33 % of the Salmonella spp. strains, respectively. Among the Salmonella spp. (n = 39) strains isolated from fecal samples of pigs, the higher frequency of resistance was observed to tetracycline, followed by amoxicillin, gentamicin, ampicillin, trimethoprim-sulfamethoxazole, nalidixic acid, cefoxitin, and norfloxacin. All strains were susceptible to amikacin. Forty-eight (78.68 %) of the E. coli strains were classified as multidrug-resistant, whereas among Salmonella spp. strains, the percentage of multidrug resistance was 57.14 %, being all multidrug-resistant strains isolated from pigs (92.30 %). The results from the present study indicate a high frequency of antimicrobial resistance among pathogenic E. coli strains isolated from calves and Salmonella spp. strains isolated from pigs and a high rate of susceptibility to most antimicrobials tested among Salmonella spp. strains isolated from calves. Our study highlights the presence of multidrug-resistant strains of E. coli and Salmonella spp. isolated from food-producing animals in Minas Gerais, Brazil.
authors.affiliation: Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Minas Gerais, Brazil.
authors.forename: Monalisa S M
authors.initials: MS
authors.lastname: Souto
authors.affiliation: Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Minas Gerais, Brazil.
authors.forename: Fernanda M
authors.initials: FM
authors.lastname: Coura
authors.affiliation: Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Minas Gerais, Brazil.|Departamento de Medicina Veterinária, Universidade Federal de Lavras, Minas Gerais, Brazil.
authors.forename: Elaine M S
authors.initials: EM
authors.lastname: Dorneles
authors.affiliation: Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Minas Gerais, Brazil.
authors.forename: Ana Paula R
authors.initials: AP
authors.lastname: Stynen
authors.affiliation: Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Minas Gerais, Brazil.
authors.forename: Telma M
authors.initials: TM
authors.lastname: Alves
authors.affiliation: Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Minas Gerais, Brazil.
authors.forename: Jordana Almeida
authors.initials: JA
authors.lastname: Santana
authors.affiliation: Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Minas Gerais, Brazil.
authors.forename: Rebeca B
authors.initials: RB
authors.lastname: Pauletti
authors.affiliation: Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Minas Gerais, Brazil.
authors.forename: Roberto M C
authors.initials: RM
authors.lastname: Guedes
authors.affiliation: Laboratório de Patologia Veterinária, Universidade Federal do Paraná, Campus Palotina, Paraná, Brazil.
authors.forename: Aline M
authors.initials: AM
authors.lastname: Viott
authors.affiliation: Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Marcos B
authors.initials: MB
authors.lastname: Heinemann
authors.affiliation: Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Minas Gerais, Brazil. alage@vet.ufmg.br.
authors.forename: Andrey P
authors.initials: AP
authors.lastname: Lage
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001938:Brazil; D002417:Cattle / Q000382:microbiology; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000302:isolation & purification*; D005243:Feces; D008826:Microbial Sensitivity Tests; D010802:Phylogeny; D019779:Salmonella enterica / Q000187:drug effects / Q000302:isolation & purification*; D034421:Sus scrofa / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antimicrobial resistance; Calves; Escherichia coli; Pigs; Salmonella