The use of zinc oxide among pig famers has tripled since 2005. The supplement helps pigs fight of some types of bacteria, but not the antibiotic resistant – and also zinc resistant – MRSA bacteria.
“When zinc inhibits the growth of other bacteria, it allows the MRSA bacteria thrive,” Henrik Westh from the MRSA knowledge centre told Politiken.
An overlooked problem
Hans Jørn Kolmos, a professor of microbiology at the University of Southern Denmark, called zinc use “an overlooked problem”.
“Zinc consumption in pigs is a major problem for people because it cultivates MRSA in pigs, which is transmitted to humans,” he told Politiken.
The zinc oxide is used to prevent diarrhoea in piglets that are removed from their mothers after four weeks. It is legal to mix the supplement with the piglets food for the first 14 days after they are taken away.
More zinc, less antibiotics
Antibiotics had also been used to fight diarrhoea in pigs, but as their use has dropped, the amount of zinc used had increased.
“That is probably why we are in this trap of more and more types of resistant bacteria,” said Kolmos.