Antimicrobial Susceptibility Patterns of Enterococcus faecalis and Enterococcus faecium Isolated from Poultry Flocks in Germany

Between 2010 and 2011, 145 Enterococcus isolates (Enterococcus faecalis, n = 127; Enterococcus faecium, n = 18) were collected during routine bacteriologic diagnostics from broilers, layers, and fattening turkeys in Germany showing various clinical signs. The susceptibility to 24 antimicrobial agents was investigated by broth microdilution test to determine minimum inhibitory concentrations (MICs). All E. faecalis isolates (n = 127) were susceptible to the beta-lactam antibiotics ampicillin, amoxicillin-clavulanic acid, and penicillin. Corresponding MIC with 50% inhibition (MIC50) and MIC with 90% inhibition (MIC90) values of these antimicrobial agents were at the lower end of the test range (≤4 µg/ml). In addition, no vancomycin-resistant enterococci (VRE) were found. High resistance rates were identified in both Enterococcus species for lincomycin (72%–99%) and tetracycline (67%–82%). Half or more than half of Enterococcus isolates were resistant to gentamicin (54%–72%) and the macrolide antibiotics erythromycin (44%–61%) and tylosin-tartate (44%–56%). Enterococcus faecalis isolated from fattening turkeys showed the highest prevalence of antimicrobial resistance compared to other poultry production systems. Eighty-nine out of 145 Enterococcus isolates were resistant to three or more antimicrobial classes. Again, turkeys stood out with 42 (81%) multiresistant isolates. The most-frequent resistance patterns of E. faecalis were gentamicin, lincomycin, and tetracycline in all poultry production systems. Patrones de susceptibilidad antimicrobiana de Enterococcus faecalis y Enterococcus faecium aislados en parvadas avícolas en Alemania. Entre los años 2010 y 2011, 145 aislamientos de Enterococcus (Enterococcus faecalis, n = 127 y de Enterococcus faecium, n = 18) se recolectaron durante el diagnóstico bacteriológico de rutina en pollos de engorde, gallinas de postura y pavos de engorde en Alemania que mostraron diferentes signologías clínicas. Se investigó la susceptibilidad contra 24 agentes antimicrobianos mediante la prueba de microdilución en caldo para determinar las concentraciones mínimas inhibitorias (con las siglas en inglés MIC). Todos los aislamientos de E. faecalis (n = 127) fueron sensibles a los antibióticos beta-lactámicos, ampicilina, amoxicilina-ácido clavulánico y penicilina. Los valores correspondientes con concentraciones mínimas inhibitorias de 50% (MIC50) y de 90% (MIC90) para estos agentes antimicrobianos se encontraron en el