University of Nebraska Diagnostic Laboratory

January 1996 through March 1998

Below are presented in vitro sensitivity data on bovine isolates obtained from cases of BRD at the University of Nebraska Veterinary Diagnostic Laboratory, Lincoln, from January 1996 through March 10, 1998.

Florfenicol continues to demonstrate outstanding activity against the three major bacteria associated with BRD. There is evidence of increasing resistance to other antibiotics commonly employed in the treatment of this disease.

Number Tested / Percent Sensitive

Mannheimia (Pasteurella) haemolytica

  1996 1997 1998
Florfenicol 29/100 78/100 64/100
Spectinomycin 32/62.5 77/57.1 65/60
Tetracycline 32/78.1 78/66.8 65/56.9
Tilmicosin 32/87.5 77/76.6 64/68.7

Pasteurella multocida

  1996 1997 1998
Florfenicol 10/100 43/100 38/100
Spectinomycin 13/100 45/64.4 41/82.9
Tetracycline 13/100 45/80 41/73.2
Tilmicosin 13/92.3 45/88.9 41/92.2

Haemophilus somnus

  1996 1997 1998
Florfenicol 12/100 29/100 17/100
Spectinomycin 13/84.6 29/72.4 17/76.5
Tetracycline 13/92.3 29/86.2 17/88.2
Tilmicosin 13/69.2 28/57.1 16/62.5