Objectives: In veterinary medicine, staphylococci play an important role as causative agents of a wide variety of infections. To determine the actual antimicrobial susceptibility status of staphylococci of veterinary relevance in Germany, several monitoring studies, including BfT-GermVet and GERM-Vet, have been conducted during recent years.
Methods: Minimum inhibitory concentration (MIC) values were determined by broth microdilution using custom-made microtitre plates. MIC₅₀ and MIC₉₀ values were calculated and, as far as approved breakpoints were available, the isolates were classified as susceptible, intermediate or resistant. Molecular analysis for the presence of genes responsible for selected resistance properties was conducted by PCR. Methicillin-resistant Staphylococcus aureus (MRSA) isolates were investigated by MLST and spa typing and analysed for SCCmec types and resistance genes.
Results and Conclusions: Regardless of the Staphylococcus spp., the animal hosts from which the staphylococci originated, and the disease conditions in which they have been involved, rather uniform susceptibility patterns were detected. Resistance to penicillins was seen most frequently, followed by resistance to tetracyclines. Depending on the animal host and the disease condition, resistances to macrolides or sulfonamides/potentiated sulfonamides were ranked at third and fourth position. Solely for S. aureus isolates from poultry, tetracycline resistance was the most frequently detected resistance property. Analysis of macrolide and/or lincosamide resistance genes revealed the presence of the genes erm(A-C), msr(A), mph(C), and lnu(A). MRSA were seen very rarely; only five porcine MRSA of sequence type 398 and spa types t011 or t034 were detected in the BfT-GermVet study.