Allen HK. mBio. 2011;doi:10.1128/mBio.00260-11.
Researchers have found that antibiotics in swine feed
stimulated gene exchange in the intestinal microbial community and could
therefore lead to transfer of antibiotic-resistant genes, according to new
findings published in mBio.
“Although antibiotics are a cost-effective tool for
improving feed efficiency and preventing disease in agricultural animals, the
full scope of their collateral effects is not understood,” according to
Heather K. Allen, of the US Department of Agriculture’s National
Animal Disease Center, and colleagues.
Metagenomics was used to examine the effects of two
antibiotics — carbadox and ASP250 (chlortetracycline, sulfamethazine and
penicillin) in feed. Researchers monitored the effect on swine intestinal
microbial communities using 16S rRNA gene sequencing.
Results indicated that ASP250, but not carbadox, caused
significant changes in both the bacteria and phages. The researchers also
identified antibiotic-resistant genes in the viromes. “This suggests that
in-feed antibiotics are contributing to phage-mediated gene transfer,
potentially of antibiotic resistance genes, in the swine gut,” Allen and
colleagues wrote in the study.
“This study advances our knowledge of the
collateral effects of in-feed antibiotics at a time in which the widespread use
of ‘growth-promoting’ antibiotics in agriculture is under
scrutiny…Understanding the role of phages in gut microbial ecology is an
essential component of the antibiotic resistance problem and of developing
potential mitigation strategies,” according to the researchers.