Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP) in skin infections from company animals in Portugal (2013-2021)

The increasing of multiresistant bacteria worldwide is one of the great concerns in both human and veterinary medicine. Bacterial dermatitis is a frequent problem in small animals, with the primary skin pathogens being Staphylococcus species. Treatment has been made more difficult by the emergence of antibiotic resistance in staphylococcal bacteria in the form of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP). The study aimed to investigate MRSA and MRSP in pyodermas admitted to the INNO Veterinary Laboratory (Braga, Portugal), in the period 2013-2021. All microbiological cultures from skin infections from dogs and cats submitted to the INNO Veterinary Laboratory between January 2013 to June 2021 were considered. For the study, only samples with S. aureus and S. pseudintermedius growth were selected. In those two agents’ methicillin resistance was phenotypically detected in the laboratory by MIC determination and by disc diffusion to oxacillin. From a total of 730 samples that tested positive for bacterial growth, 101 (13,8%) were S. pseudointermedius and 27 (3,7%) were S. aureus. The isolates tested for oxacillin 9% (n=6) were MRSP and 6% (n=4) MRSA. The results obtained in this study helps to understand the situation at a national level, where studies in this area are almost non-existent. The presence of MRSA or MRSP in small animals indicates that they are part of the animal-human-environment transmission 'triangle', which should lead us to think of this issue as a public health problem.