Antimicrobial Resistance of Erysipelothrix rhusiopathiae Strains Isolated from Geese to Antimicrobials Widely Used in Veterinary Medicine.

Abstract

The aim of this study was to determine the antibiotic resistance of E. rhusiopathiae when isolated from clinical outbreaks of erysipelas in geese to antimicrobials commonly used in poultry production. All isolates were susceptible to amoxicillin alone or with clavulanic acid, with MIC values ranging from 0.016 to 0.125 μg/mL. Ninety-six percent of isolates were fully sensitive to penicillin G (MIC 0.125-0.5 μg/mL). All isolates were fully or moderately sensitive to erythromycin (MIC 0.125-0.5 μg/mL). Most E. rhusiopathiae isolates proved resistant to fluoroquinolones (76.6% of isolates were resistant to enrofloxacin, with MIC values ranging from 0.064 to 32 μg/mL, and 68% were resistant to norfloxacin, with MIC values ranging from 0.094 to 96 μg/mL), and tetracyclines (61.7% of isolates were resistant to doxycycline, with MIC values ranging from 0.25 to 64 μg/mL, and 63.8% were resistant to tetracycline, with MIC values ranging from 0.38 to 256 μg/mL). Point mutations in the gyrA gene (responsible for fluoroquinolone resistance) and the presence of the tetM gene (responsible for tetracycline resistance) were noted in most of the resistant isolates. Multidrug resistance, defined as resistance to at least one substance in three or more antimicrobial classes, was not observed.