Quantitative sensitivity of frequently isolated veterinary pathogens as ascertained by multicentric studies in comparison to chemotherapeutics used in veterinary medicine - Part I: E. coli-bovine and porcine strains

During a study on quantitative determination of resistance in veterinary pa thogens, 24 German laboratories for veterinary diagnostics sent 259 E. coli , 246 Staphylococcus aureus and Staph. intermedius, 172 Pasteurella multoci da and Mannheimia (Past.) haemolytica strains, isolated from diseased anima ls, to the BgVV for a sensitivity test in comparison to 16 widely used chem otherapeutics. The isolates were taken from cattle (calf, cow), swine, dog and cat. On a questionnaire the laboratories indicated - as far as these de tails were known to them - the origin of the pathogen (place, stock), the s ize of the stock, the age of the animal, the kind of disease and the kind o f sample. The results are divided into three parts: Part I describes the re sults of the E. coli of the cattle udder, of the calf/young cattle and of t he swine. - By means of a micro broth dilution test, the minimal inhibitory concentration (MIC) of 259 Escherichia coli strains, isolated from udder s ecretions as well as from calves or young cattle and swine, was determined for 10-12 antibacterial substances. In 1999 the E. coli of the cattle udder was isolated in 13 veterinary laboratories responsible for 86 German munic ipalities or towns in 8 German Lander and sent to the BgVV, the E. coli of the calf/young cattle in 12 veterinary laboratories responsible for 55 muni cipalities or towns in 8 Lander and the E. coli of the swine in 13 veterina ry laboratories responsible for 66 municipalities or towns in 9 countries. At the same time, a second sensitivity test, the agar diffusion test, was c arried out to determine the diameter of the inhibition zone. The MIC and th e inhibition zone diameter were evaluated according to limit values, most o f which were adopted by the German standard DIN 58 940 and included into a veterinary protocol for the determination of resistance in fast-growing bac teria. In the conclusions attention is drawn to the importance of the sprea ding of resistances for specific therapies.