FIG. 1.

Percent resistance to nalidixic acid (NAL; inhibition zone, ≤13 mm) and relative MICs of enrofloxacin (ENR; susceptible, intermediate, resistant) for nalidixic acid-resistant, nonhuman salmonella strains isolated in Germany between 1986 and 1998 (received between January and October 1998). (A) Total rate for all isolates. (B) Isolates from cattle. (C) Isolates from poultry. (D) Isolates from pigs. The arrows indicate the dates of licensing of enrofloxacin for veterinary use in Germany (for pigs and cattle, May 1989; for poultry, January 1990). N is the number of isolates investigated.