Allen:
> Seeing as we are exchanging opinions here, I'll repeat mine: IMO, extender patties were part of the solution, not part of the cause.

I sort of agree here. I think that it is highly unlikely that the use of antibiotics as a preventative would lead to widespread resistance, as resistance develops in an active infection, not in spores. In other words, an active AFB infection that was treated with terramycin would more likely yield a subpopulation of resistant bacteria. How could resistance develop in colonies that *don't have AFB?* If it is prevented, there is no infection to yield resistant strains, whereas exposing a full blown AFB infection to terramycin would kill off all susceptible bacteria, leaving only the resistant strains to propagate. Finally, I agree that this issue is very complicated and very little actual study has been done on TM resistant AFB, other than to find other antibiotics to use.

Relevant material:


> Antimicrobial resistance (AMR) among bacteria is a growing global concern for human and animal health. It is a complex issue that should not be oversimplified or over-generalized because there is not a simple, direct relationship between antimicrobial drug (AMD) use and AMR. Conscientious use of AMDs is among the first-line control measures that are recommended for combating AMR in feedlots. 

> However, it remains unproven that increased use of AMDs in feedlot cattle creates meaningful increases in resistance among pathogenic or nonpathogenic bacteria recovered from these animals, or that such increased resistance increases health risks for humans. Although there were some associations detected between the in-feed exposure of AMD and AMR in these feedlots in this study, differences associated with treatment were small and of unknown relevance.

Antimicrobial Drug Use and Antimicrobial Resistance in Enteric Bacteria Among Cattle from Alberta Feedlots. FOODBORNE PATHOGENS AND DISEASE Volume 7, Number 4, 2010 

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