The poultry industry in the USA is a fully integrated system of animal agriculture. Each company has control over the bird husbandry and health management aspects of production, including the use of antimicrobial agents. The three segments of the industry-broiler chickens, turkeys, and layer chickens-have few antibiotics available for the therapeutic treatment of bacterial diseases. Prior to approval of the fluoroquinolones, tetracyclines were the major antibiotics approved for the treatment of the most economically important disease in broiler chickens and turkeys, Escherichia coli airsacculitis. This resulted in levels of resistance to the tetracyclines in clinical E. coli isolates in excess of 90%. The integrated nature of the poultry industry lends itself well to preventive medicine utilizing the tools of biosecurity and vaccination. Therefore, very few flocks of birds require antibiotic therapy. When a flock must be treated, the poultry veterinarian will usually base the recommendation of the drug to use on culture and antibiogram results.