Poster presentado en Antimicrobial Resistance in Zoonotic Bacteria and Foodborne Pathogens in Animals, Humans and the Environment

8 de junio de 2010

Cavaco LM., Hasman H., Wagenaar JA., Graveland H., Mevius D., Veldman K., Fetsch A., Tenhagen BA., Porrero MC., Dominguez L., Jouy E., Granier SA., Butaye P., Kaszanyitzky E., Dan A., Zmudzki J., Battisti A., Franco A., Schwarz S., Gutierrez M. y Aarestrup FM.

Background Methicillin resistant Staphylococcus aureus (MRSA) have been recently found widespread among livestock populations and are considered as an emerging threat to Public Health, due to occupational transmission to humans. We recently reported a phenotypic association between reduced susceptibility to zinc and methicillin resistance in MRSA CC398 from Danish swine and have identified czrC as a resistance gene conferring resistance to zinc and cadmium. The aim of this study was to determine the occurrence of metal resistance in MRSA of animal origin in Europe and examine the prevalence of czrC. Methods A total of 455 MRSA isolates were isolated from dust samples on pig farms in nine countries in Europe (DE, DK, HU, PL, IT, ES, BE, FR and NL) as part of the baseline studies performed by EC Decision in 2008. In addition, 92 MRSA isolates from veal calves (NL), 28 MSSA isolates from pigs (IE, DE and PL) and 60 MSSA from veal calves (NL) were included. The identification was confirmed by PCR and all MRSA were typed using spa typing and allocated into a CC using Ridom spa server data and/or confirmatory MLST. All MRSA and MSSA isolates were tested for susceptibility towards zinc chloride and copper sulphate using agar dilution method and tested by PCR for the presence of czrC. The data were analysed statistically using chi square or Fishers exact test on two by two tables. Results A total of 510 of the MRSA belonged to CC398, while 37 MRSA belonged to other CC-types. Phenotypic zinc resistance (MIC>2mM) was observed in 73% and 42% of MRSA CC398 from pigs and veal calves, respectively. czrC was detected in 69% and 41% MRSA among pigs and veal calf, respectively and was strongly associated with phenotypic zinc resistance (99% agreement). Among the 37 non-CC 398 MRSA, 60% were resistant towards zinc chloride, but only 42% of these were positive for czrC, suggesting the presence of other resistance determinants. By country, prevalences of czrC varied from 35% to 92% among MRSA CC398 and from 0% to 50% in non-CC398 isolates from pigs. None of the MSSA tested carried czrC and MIC to zinc chloride ranged from 1 to 4 mM. The MICs of copper sulphate of both MRSA and MSSA were between 4-24mM and were neither associated with methicillin resistance nor with detection of czrC. Discussion and conclusions The results show that zinc resistance conferred by czrC gene is widespread among MRSA CC398 from pigs in Europe. Among the veal calf isolates from NL the prevalence of zinc resistance and czrC was lower than observed for the pig isolates. The susceptibility data suggests that additional zinc resistance determinants may be present among non-CC398 MRSA.In some European countries zinc compounds are used very frequently in feed of production animals for control of diarrhoea. Thus, our findings indicate that the use of zinc might have contributed to the emergence of MRSA in food producing animals in Europe of and/or to its further spread

	Servicio de Zoonosis de Transmisión Alimentaria y Resistencia a Antimicrobianos (ZTA). Centro de Vigilancia Sanitaria Veterinaria (VISAVET). Universidad Complutense (UCM).
	Departamento de Sanidad Animal. Facultad de Veterinaria. Universidad Complutense (UCM).

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