RESUMO
A retrospective study was conducted to determine the prevalence of antimicrobial resistance among Pasteurella spp recovered from cattle with bovine respiratory disease complex. The study extended from January 1976 through May 1980, and included a review of the necropsy records of 386 beef cattle. Susceptibility or resistance of the Pasteurella isolants was determined by using the standard disk diffusion susceptibility test. Each isolant was tested for susceptibility with 15 different antimicrobial agents. A high prevalence of resistance (greater than 80%) was found when Pasteurella was tested with triple sulfonamides. For P haemolytica isolants, 57% to 70% were resistant to ampicillin (56/97), penicillin (58/101), and streptomycin (70/100); for unidentified Pasteurella spp isolants, 64% to 91% were resistant to ampicillin (83/129), penicillin (89/129), and streptomycin (118/129). For P haemolytica (21/100) and P multocida (34/146) isolants, 21% to 23% were resistant to tetracycline. Most of the P multocida isolants did not show marked antimicrobial resistance to 9 of the 15 drugs tested. However, 58% of the P multocida isolants (84/145) were resistant to streptomycin and 88% of them were resistant to three combined sulfonamides (126/144).
Assuntos
Antibacterianos/farmacologia , Doenças dos Bovinos/microbiologia , Pasteurella/efeitos dos fármacos , Infecções Respiratórias/veterinária , Animais , Antibacterianos/administração & dosagem , Antibacterianos/uso terapêutico , Bovinos , Doenças dos Bovinos/tratamento farmacológico , Combinação de Medicamentos , Resistência Microbiana a Medicamentos , Eritromicina/administração & dosagem , Eritromicina/uso terapêutico , Iowa , Missouri , Infecções Respiratórias/tratamento farmacológico , Infecções Respiratórias/microbiologia , Estudos RetrospectivosRESUMO
Tall fescue (Festuca arundinacea Shreb) hay from a source known to cause "fescue foot" in grazing cattle was extracted with 80% ethanol. The ethanolic extract was further refined and fractionated into cation,nion, and neutral f fractions by ion-exchange chromatography. The cation fraction was partitioned with alkaline-chloroform to give chloroform-extractable cation and residual cation fractions. All fractions plus the crude ethanolic extract were assayed for toxic activity by intraperitoneal injection into 12 calves (weighting 152.4 to 241.3 kg each) over a 14-day period. Clinical signs of fescue foot were observed on the 5th day in calves given the anion and crude ethanolic extracts. Lameness, swelling, and reddening of the rear coronary bands, discoloration of the tip of the tail, and other signs of fescue foot were seen. Microscopically, coronary bands and tail tips of affected calves had blood vessels with thick walls and small lumens.
