title: Colistin resistance in Escherichia coli and Salmonella enterica strains isolated from swine in Brazil.
abstract: Reports about acquired resistance to colistin in different bacteria species are increasing, including E. coli of animal origin, but reports of resistance in wild S. enterica of different serotypes from swine are not found in the literature. Results obtained with one hundred and twenty-six E. coli strains from diseased swine and one hundred and twenty-four S. enterica strains from diseased and carrier swine showed a frequency of 6.3% and 21% of colistin-resistant strains, respectively. When comparing the disk diffusion test with the agar dilution test to evaluate the strains, it was confirmed that the disk diffusion test is not recommended to evaluate colistin resistance as described previously. The colistin MIC 90 and MIC 50 values obtained to E. coli were 0.25 μg/mL and 0.5 μg/mL, the MIC 90 and MIC 50 to S. enterica were 1 μg/mL and 8 μg/mL. Considering the importance of colistin in control of nosocomial human infections with Gram-negative multiresistant bacteria, and the large use of this drug in animal production, the colistin resistance prevalence in enterobacteriaceae of animal origin must be monitored more closely.
authors.affiliation: Laboratório de Sanidade Suína e Virologia, Faculdade de Medicina Veterinária e Zootecnia-FMVZ, Universidade de São Paulo-USP, 05508270 São Paulo, SP, Brazil.
authors.forename: Adriano Savoia
authors.initials: AS
authors.lastname: Morales
authors.forename: Juliana
authors.initials: J
authors.lastname: Fragoso de Araújo
authors.forename: Vasco Túlio
authors.initials: VT
authors.lastname: de Moura Gomes
authors.forename: Adrienny Trindade
authors.initials: AT
authors.lastname: Reis Costa
authors.forename: Dália
authors.initials: D
authors.lastname: dos Prazeres Rodrigues
authors.forename: Thais Sebastiana
authors.initials: TS
authors.lastname: Porfida Ferreira
authors.forename: Pedro Henrique Nogueira
authors.initials: PH
authors.lastname: de Lima Filsner
authors.forename: Maria Roberta
authors.initials: MR
authors.lastname: Felizardo
authors.forename: Andrea
authors.initials: A
authors.lastname: Micke Moreno
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001938:Brazil; D003091:Colistin / Q000494:pharmacology*; D052978:Disk Diffusion Antimicrobial Tests / Q000379:methods; D024881:Drug Resistance, Bacterial; D004760:Enterocolitis / Q000382:microbiology / Q000662:veterinary; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology; D019779:Salmonella enterica / Q000187:drug effects* / Q000302:isolation & purification; D013552:Swine / Q000382:microbiology*; D013553:Swine Diseases / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D003091:Colistin