A wide scope of antimicrobial products is available for the therapy of microbial infections in poultry. Baytril® 10% oral solution contains enrofloxacin which belongs to the class of the fluoroquinolones. Baytril® is bactericidal by inhibiting the bacterial DNA topoisomerases II (gyrase) and IV. By the action of the latter enzymes bacterial DNA is resealed during the bacterial multiplication process. The use of Baytril® and other registered fluoroquinoles is recommended for the therapy of several bacterial diseases caused by susceptible microorganisms. In poultry Baytril® is bactericidal for gram negative bacteria and mycoplasmas at low concentrations.