Pleuromutilins: use in food-producing animals in the European Union, development of resistance and impact on human and animal health

Pleuromutilins (tiamulin and valnemulin) are antimicrobial agents that are used mainly in veterinary medicine,especially for swine and to a lesser extent for poultry and rabbits. In pigs, tiamulin and valnemulin are used totreat swine dysentery, spirochaete-associated diarrhoea, porcine proliferative enteropathy, enzootic pneumoniaand other infections where Mycoplasma is involved. There areconcerns about the reported increases in the MICsof tiamulin and valnemulin for porcine Brachyspira hyodysenteriae isolates from different European countries, asonly a limited number of antimicrobials are available for the treatment of swine dysentery where resistance tothese antimicrobials is already common and widespread. The loss of pleuromutilins as effective tools to treatswine dysentery because of further increases in resistance or as a consequence of restrictions would present aconsiderable threat to pig health, welfare and productivity. In humans, only one product containing pleuromu-tilins (retapamulin) is authorized currently for topical use; however, products for oral and intravenous adminis-tration to humans with serious multidrug-resistant skin infections and respiratory infections, including thosecaused by methicillin-resistant Staphylococcus aureus (MRSA), are being developed. The objective of this reviewistosummarizethecurrentknowledgeontheusageofpleuromutilins,resistancedevelopmentandthepotentialimpact of this resistance on animal and human health.Keywords: valnemulin, tiamulin, Brachyspira hyodysenteriae, review, antimicrobial resistance