Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP) among employees and in the environment of a small animal hospital

Abstract

The aim of the study was to investigate methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP) among employees of a small animal hospital and the hospital environment. In total, 96 swabs from employees and 73 swabs from the clinic environment were investigated. Cation-adjusted-Mueller-Hinton broth (CAMHB) + 6.5% NaCl was used for enrichment before plating on Mueller-Hinton (MH) agar with 2% NaCl and 0.25 mg/L oxacillin. The staphylococcal species was determined using MALDI-TOF MS. The isolates were subjected to mecA-PCR, macrorestriction analysis, and antimicrobial susceptibility testing. MRSA were present in five nasal swabs of the 55 employees tested and in six environmental samples, MRSP in two employees (nasal and hand swabs, each) and in three environmental samples. All isolates harboured mecA. Susceptibility testing revealed that all but one of the isolates were multiresistant. All isolates were resistant to β-lactams and fluoroquinolones. All but one of the isolates were resistant to macrolides and lincosamides. A single MRSA was resistant to gentamicin. All MRSP were resistant to trimethoprim/sulfamethoxazole and non-susceptible to gentamicin. One isolate was also resistant to tetracycline. Macrorestriction analysis revealed three main SmaI patterns for MRSA and two main SmaI patterns for MRSP. All environmental isolates were found in areas of high people and animal traffic, such as dog ward areas, waiting and triage rooms. The finding of indistinguishable MRSA or MRSP among employees and in the environment of the small animal hospital suggests the possibility of transfer of these bacteria between humans, animals, and the hospital environment.

Keywords: Antimicrobial resistance; Colonization; Contamination; Molecular typing.