Nutritive and therapeutic treatment of farm animals with antibiotics, amounting to half of the world's antibiotic output, has selected for resistant bacteria that may contaminate the food produced. Antibiotic-resistant enterococci and staphylococci from animals are found in food when they survive the production processes, as in raw cured sausages and raw milk cheeses. The broad host ranges of some plasmids and the action of transposons in many bacteria allow antibiotic-resistance genes to be communicated by conjugation between different species and genera,. A multi-antibiotic resistance plasmid from a lactococcus found in cheese provides a historical record of such events.