Low Propensity for Poultry Isolates of Pasteurella multocida to Acquire Adaptive Resistance to Oxytetracycline

Abstract

Thirty independently derived reference strains and clinical isolates of Pasteurella multocida were tested to determine their potential for acquiring adaptive resistance to oxytetracycline in an effort to better understand the prolonged high efficacy of the antibiotic for pasteurellosis in poultry. All reference strains and clinical isolates exhibited uniform susceptibility as measured with the broth dilution method. None of the strains or isolates readily acquired significant resistance when grown in subinhibitory oxytetracycline levels under the conditions employed. These data support the conclusions that spontaneous variation in P. multocida resulting in oxytetracycline resistance is uncommon in the field and that the organism possesses a very low propensity for acquiring adaptive resistance in response to growth in the presence of the antibiotic.

Investigation of Japanese quail (Coturnix japonica) as a pharmacokinetic model for cockatiels (Nymphicus hollandicus) and Poicephalus parrots via comparison of the pharmacokinetics of a single intravenous injection of oxytetracycline hydrochloride

“…Except for Pasteurella multocida , the MIC of plasma OTC required to treat avian pathogens against which OTC could be expected to have good activity is not known. The MIC of OTC against P. multocida isolates from poultry ranges from 0.4 to 6.4 μ g/mL (Champlin et al. , 1988).…”

“…Except for Pasteurella multocida, the MIC of plasma OTC required to treat avian pathogens against which OTC could be expected to have good activity is not known. The MIC of OTC against P. multocida isolates from poultry ranges from 0.4 to 6.4 lg/mL (Champlin et al, 1988). In goats and cattle, a plasma OTC concentration of 0.5 lg/mL is considered efficacious against most susceptible pathogens while in dogs a concentration of 1.25-5 lg/mL is considered therapeutic (Baggot et al, 1977;Luthman & Jacobsson, 1982;Xia et al, 1983;Escudero et al, 1994).…”