First report on MRSA CC398 recovered from wild boars in the north of Portugal. Are we facing a problem?

The aim of the present study was to evaluate the resistance of Staphylococcus aureus recovered from wild boars, to analyze their genetic lineages, and to investigate the susceptibility to oxacillin. Samples from mouth and nose of 45 wild boars (Sus scrofa) were collected during hunt activity from November 2012 to January 2013 in the North of Portugal. S. aureus isolates were recovered from 30 of these samples (33%); one isolate/sample was further studied. The susceptibility of the isolates was tested by disk-diffusion test against 14 antimicrobial agents and minimal inhibitory concentration was used to test oxacillin according to EUCAST guidelines. The genetic lineages of S. aureus were characterized by agr-typing, spa-typing and MLST. From the 30 isolates, 18 S. aureus were susceptible to all antibiotics tested and 7 presented resistance to one or more of the following antibiotics: penicillin (n=3), oxacillin (n=4), cefoxitin (n=1), clindamycin (n=2), gentamicin (n=1), fusidic acid (n=1), ciprofloxacin (n=2), tetracycline (n=1) and linezolid (n=1). One MRSA CC398 (spa-type t899) isolate was detected (oxacillin MIC=32mg/L and mecA-positive), which presented resistance to penicillin, tetracycline, and ciprofloxacin and contained the genes of immune evasion cluster (IEC) system (type B). The 29 methicillin-susceptible isolates were typed as ST1 (t1533), ST133 (t3583), ST1643 (t10712), ST2328 (t3750) and the new STs (3220, 3222, 3223, 3224) associated to new spa-types t14311 and t14312. The agr-types I, II, III and IV were identified. It is a matter of concern when MRSA and some specific lineages of S. aureus are taken as commensal habitants of the skin and nose of wild animals and are characterized with resistance to various antimicrobial agents in clinical use.Margarida Andrade Sousa has her Ph.D. fellowship granted by FCT (Fundação para a Ciência e Tecnologia, Portugal) with the reference SFRH/BD/87302/2012. Vera Manageiro has her Post-Doc fellowship granted by FCT with the reference SFRH/BPD/77486/2011, both co- financed by the Social European Union Fund and the Operational Program for Human Potential and National Board for Reference and Strategic Programs (POPH/QREN), Portugal. Nuno Silva was supported by “Programa Ciência 2008” co-financed by POPH/QREN Type 4.2: Employment Promotion Scientific subsidized by the European Social Fund and National Funds of the Ministry of Science and Technology for Higher Education (MCTES). Part of this work was supported by Project SAF2016- 76571-R from the Ministerio de Economía y Competitividad of Spain and the Fondo Europeo de Desarrollo Regional (FEDER). This work was also supported by the Unidade de Ciências Biomoleculares Aplicadas (UCIBIO) which is financed by national funds from FCT/MEC (UID/Multi/04378/2013) and cofinanced by the ERDF under the PT2020 Partnership Agreement (POCI-01–0145-FEDER-007728). The authors thank FCT for project grant PEst-OE/AGR/UI0211/2011-2014, Strategic Project UI211-2011-2014 of Centre for the Study of Animal Sciences (CECA/ICETA).