Ceftiofur concentrations in an infected and uninfected environment were compared and the efficacy of locally administered
ceftiofur was evaluated in an experimental
infection with Staphylococcus aureus in
tissue cages. Eight ponies had
tissue cages (TCs) implanted s.c. on each side of the neck. Into one of the cages 150 mg of
ceftiofur was administered and fluid samples were taken to determine
ceftiofur concentrations. After 1 week the other TC was infected with S. aureus and subsequently treated with 150 mg
ceftiofur administered locally into the TC once daily for 21 days. Samples of fluid were taken to determine
ceftiofur concentrations and for bacterial counts.
Ceftiofur concentrations did not differ significantly in the infected and uninfected environments after single dose of 150 mg of
ceftiofur. Concentrations were considerably in excess of the minimum inhibitory concentration (MIC) of the S. aureus strain used. A marked decrease of viable bacteria in
tissue cage fluid (TCF) occurred. In five of seven ponies; however, the
infection was not eliminated and
abscess formation occurred. Therefore, local application of
ceftiofur alone is not advisable for
infections with S. aureus in secluded sites in horses, but should be used only with adjunctive
therapy.