Some growth promoters in animals do confer antimicrobial resistance in humansBMJ 1999; 318 doi: https://doi.org/10.1136/bmj.318.7190.1076b (Published 17 April 1999) Cite this as: BMJ 1999;318:1076
EDITOR—In his editorial on the veterinary perspective of antimicrobial resistance McKellar says that in the United Kingdom only antimicrobials that are not used in human medicine and those which do not select for cross resistance with antimicrobials used in humans are available for performance enhancement.1
In fact, tylosin and spiramycin confer cross resistance to the macrolide erythromycin, which is an important antimicrobial drug for humans. In 1969 the Swann committee recommended that tylosin should not be available as a growth promoter.2 As a consequence of the widespread use of spiramycin and tylosin for growth promotion as well as for treatment of animal diseases, macrolide resistance is prevalent in Campylobacter spp, which are important zoonotic bacteria transferred from animals to humans through the food chain.
As McKellar says, virginiamycin confers cross resistance to streptogramins used in human medicine.3 This was the background behind the ban on using virginiamycin as a growth promoter in Denmark from January 1998. However, this agent is still available in the United Kingdom. Furthermore, a recent study showed cross resistance between the growth promoter avilamycin and everninomycin (SCH 27899), a new drug for treating multiresistant infections in humans.4
In conclusion, several of the currently approved and most widely used growth promoters confer cross resistance to antimicrobial agents used in treating humans.