High frequency of coagulase-positive staphylococci carriage in healthy wild boar with detection of MRSA of lineage ST398-t011

Abstract

The objective of this study was to determine the frequency and diversity of coagulase-positive staphylococci (CoPS) in nasal samples of healthy wild boar, to study their resistance phenotypes/genotypes and to check the occurrence of the MRSA-ST398. Nasal samples of 371 wild boars were collected in Spain for staphylococci and MRSA recovery. Staphylococci identification was performed by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF). The susceptibility to 11 antimicrobials was tested by disc-diffusion and the presence of resistance genes by PCR. Molecular typing and virulence factors determination were carried out by PCR and sequencing. The rate of CoPS carriage (Staphylococcus aureus, Staphylococcus hyicus and Staphylococcus pseudintermedius) in wild boar was of 17.8% (13.7%, 2.7% and 1.6%, respectively). Susceptibility to all tested antimicrobials was shown in 74.5% of S. aureus and one strain was MRSA [lineage ST398-t011-agrI, carrying blaZ, mecA, tet(M) and tet(K) genes]. A total of 22 spa-types and 17 STs were detected among S. aureus, including: ST398/CC398 (n = 1), ST2328-ST133/CC133 (n = 20), ST425/CC425 (n = 7), ST5/CC5 (n = 5), ST1/CC1 (n = 3), ST130/CC130 (n = 2) and ST88/CC88 (n = 1). Two spa-types (t02, t15) and four STs (ST455, ST796, ST797, ST798) were detected among the six S. pseudintermedius isolates recovered, and all of them carried the lukF/S-I and siet virulence genes. All S. hyicus isolates were susceptible to antimicrobials tested.

Keywords: S. aureus; S. hyicus; S. pseudintermedius; CC398; MRSA; wild boar.