In the United States, the use of antibiotics in livestock 
  is still prevalent. The FDA reports that 80 percent of 
  all antibiotics sold in 2009 were administered to 
  livestock animals, and that many of these antibiotics are 
  identical or closely related to drugs used for treating 
  illnesses in humans. Consequently, many of these drugs 
  are losing their effectiveness on humans, and the total 
  healthcare costs associated with drug-resistant bacterial 
  infections in the United States are between $16.6 billion 
  and $26 billion annually

The same goes for some countries in Europe. And as companies are importing goods from cheap farming companies such food can be found everywhere.