title: Establishing streptomycin epidemiological cut-off values for Salmonella and Escherichia coli.
abstract: This study was conducted to elucidate the accuracy of the current streptomycin epidemiological cut-off value (ECOFF) for Escherichia coli and Salmonella spp. A total of 236 Salmonella enterica and 208 E. coli isolates exhibiting MICs between 4 and 32 mg/L were selected from 12 countries. Isolates were investigated by polymerase chain reaction for aadA, strA, and strB streptomycin resistance genes. Out of 236 Salmonella isolates, 32 (13.5%) yielded amplicons for aadA (n = 23), strA (n = 9), and strB (n = 11). None of the 60 Salmonella isolates exhibiting MIC 4 mg/L harbored resistance genes. Of the Salmonella isolates exhibiting MICs 8 mg/L, 16 mg/L, and 32 mg/L, 1.6%, 15%, and 39%, respectively, tested positive for one or more genes. For most monitoring programs, the streptomycin ECOFF for Salmonella is wild type (WT) ≤32 or ≤16 mg/L. A cut-off value of WT ≤32 mg/L would have misclassified 13.5% of the strains as belonging to the WT population, since this proportion of strains harbored resistance genes and exhibited MICs ≤32 mg/L. Out of 208 E. coli strains, 80 (38.5%) tested positive for aadA (n = 69), strA (n = 18), and strB (n = 31). Of the E. coli isolates exhibiting MICs of 4 mg/L, 8 mg/L, 16 mg/L, and 32 mg/L, 3.6%, 17.6%, 53%, and 82.3%, respectively, harbored any of the three genes. Based on the European Committee on Antimicrobial Susceptibility Testing guidelines (ECOFF ≤16 mg/L), 25% of the E. coli strains presenting MIC ≤16 mg/L would have been incorrectly categorized as belonging to the WT population. The authors recommend an ECOFF value of WT ≤16 mg/L for Salmonella and WT ≤8 mg/L for E. coli.
authors.affiliation: National Food Institute, Technical University of Denmark, Lyngby, Denmark. lourdes.migura@cresa.uab.cat
authors.forename: Lourdes
authors.initials: L
authors.lastname: Garcia-Migura
authors.forename: Marianne
authors.initials: M
authors.lastname: Sunde
authors.forename: Susanne
authors.initials: S
authors.lastname: Karlsmose
authors.forename: Kees
authors.initials: K
authors.lastname: Veldman
authors.forename: Andreas
authors.initials: A
authors.lastname: Schroeter
authors.forename: Beatriz
authors.initials: B
authors.lastname: Guerra
authors.forename: Sophie A
authors.initials: SA
authors.lastname: Granier
authors.forename: Agnès
authors.initials: A
authors.lastname: Perrin-Guyomard
authors.forename: Mireille
authors.initials: M
authors.lastname: Gicquel-Bruneau
authors.forename: Alessia
authors.initials: A
authors.lastname: Franco
authors.forename: Stina
authors.initials: S
authors.lastname: Englund
authors.forename: Christopher
authors.initials: C
authors.lastname: Teale
authors.forename: Helmi
authors.initials: H
authors.lastname: Heiska
authors.forename: Lurdes
authors.initials: L
authors.lastname: Clemente
authors.forename: Patrick
authors.initials: P
authors.lastname: Boerlin
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Moreno
authors.forename: Danielle
authors.initials: D
authors.lastname: Daignault
authors.forename: Dik
authors.initials: D
authors.lastname: Mevius
authors.forename: Rene S
authors.initials: RS
authors.lastname: Hendriksen
authors.forename: Frank M
authors.initials: FM
authors.lastname: Aarestrup
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D005060:Europe / Q000453:epidemiology; D005798:Genes, Bacterial; D058751:Livestock; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D011200:Poultry; D017410:Practice Guidelines as Topic; D012475:Salmonella / Q000187:drug effects / Q000235:genetics*; D012481:Salmonella Infections, Animal / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D013307:Streptomycin / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D013307:Streptomycin