Background: Mupirocin is one of the few antimicrobials active against methicillin-resistant Staphylococcus aureus (MRSA), and is frequently used for the eradication of MRSA nasal colonisation in humans. Initially, mupirocin resistance was recognised in human S. aureus, including MRSA isolates, then also among coagulase-negative staphylococci (CoNS). Nowadays, mupirocin resistance is occasionally observed in canine staphylococci, along with Staphylococcus pseudintermedius (MRSP) strains, as well as CoNS, which usually show methicillin resistance. In the current study, high-level mupirocin resistance in methicillin-resistant staphylococci isolated from diseased dogs and cats was investigated.
Results: Among 140 methicillin-resistant staphylococci isolates from dogs and cats, three showed high-level mupirocin resistance in a screening test using the agar disk diffusion method. One was recognised as methicillin-resistant S. aureus, one as methicillin-resistant S. pseudintermedius, and one as methicillin-resistant Staphylococcus haemolyticus. S. pseudintermedius and S. aureus were isolated from dogs, S. haemolyticus was obtained from a cat. All isolates showed high-level mupirocin resistance, confirmed by minimum inhibitory concentration (MIC) values of above 1024 μg/ml and the presence of the plasmid-located gene ileS2. This is the first report on the detection of high-level mupirocin resistance (HLMR) in S. haemolyticus of feline origin.
Conclusions: This study revealed the occurrence of HLMR in three Staphylococcus isolates obtained from companion animals in Poland. The results of this study indicate that the monitoring of mupirocin resistance in staphylococci of animal origin, especially in methicillin-resistant isolates, is strongly recommended.
Keywords: Staphylococcus aureus; Staphylococcus haemolyticus; Staphylococcus pseudintermedius; ileS2.