Antimicrobial resistance represents a major global threat to modern medicine. In vitro studies have shown that very low concentrations of drugs, as frequently identified in the environment, and in foods and water for @entity1 and animal consumption, can select for resistant bacteria. However, limited information is currently available on the in vivo impact of ingested drug residues. The objective of our study was to evaluate the effect of feeding preweaned @entity291 @entity6155 containing antimicrobial drug residues (below the minimum inhibitory concentration), similar to concentrations detected in @entity6155 commonly fed to dairy @entity291 , on selection of resistant fecal @entity526 in @entity291 from birth to weaning. At birth, thirty @entity291 were randomly assigned to a controlled feeding trial where: 15 @entity291 were fed raw @entity6155 with no drug residues (NR), and 15 @entity291 were fed raw @entity6155 with drug residues (DR) by adding @entity21563 , @entity114 , @entity869 , and @entity5385 at final concentrations in the @entity6155 of 0.1, 0.005, 0.01, and 0.3   g/ml, respectively. Fecal samples were rectally collected from each @entity291 once a week starting at birth prior to the first feeding in the trial (pre-treatment) until 6 weeks of age. A significantly greater proportion of @entity526 resistant to @entity869 , @entity3398 , @entity21563 , @entity3639 and @entity803 was observed in DR @entity291 when compared to NR @entity291 . Additionally, isolates from DR @entity291 had a significant decrease in susceptibility to @entity2756 and @entity21563 when compared to isolates from NR @entity291 . A greater proportion of @entity526 isolates from @entity291 in the DR group were resistant to 3 or more antimicrobial drugs when compared to @entity291 in the @entity11702 group. These findings highlight the role that low concentrations of antimicrobial drugs have on the evolution and selection of resistance to multiple antimicrobial drugs in vivo.

In Vivo Selection of Resistant XXXX after Ingestion of @entity6155 with Added Drug Residues.

@entity1 :: ('9606', 'Species') :: ['human'] @entity21563 :: ('MESH:C053503', 'Chemical') :: ['ceftiofur'] @entity2756 :: ('MESH:D002443', 'Chemical') :: ['ceftriaxone'] @entity114 :: ('MESH:D010406', 'Chemical') :: ['penicillin'] @entity5385 :: ('MESH:D010118', 'Chemical') :: ['oxytetracycline'] @entity3639 :: ('MESH:D013307', 'Chemical') :: ['streptomycin'] @entity11702 :: ('MESH:C537849', 'Disease') :: ['ND'] @entity6155 :: ('100532204', 'Gene') :: ['milk'] @entity869 :: ('MESH:D000667', 'Chemical') :: ['ampicillin'] @entity803 :: ('MESH:D013752', 'Chemical') :: ['tetracycline'] @entity291 :: ('9913', 'Species') :: ['calf', 'calves'] @entity3398 :: ('MESH:D002440', 'Chemical') :: ['cefoxitin'] @entity526 :: ('562', 'Species') :: ['E. coli']
@entity526 :: (562,Species) :: ['E. coli']
