[Characterization of isolates of Paenibacillus larvae with biochemical type and oxytetracycline resistance].

A collection of 91 isolates from different geographical origins of Paenibacillus larvae, the etiologic agent of American Foulbrood disease of honey bees, was characterized according to its biochemical type and susceptibility to oxytetracycline hydrochloride (OTC), the most commonly used antibiotic for the control of the disease. The majority of the Argentinian strains corresponded to the biochemical type II while only one culture from Río Negro (Argentina), one from Buenos Aires (Argentina) and one from Córdoba (Argentina) presented characteristics of type V. In relation to their response to OTC it was found a 48% resistance within the collection of Argentinian strains; for this group, the values of minimal inhibitory concentration (MIC) were 10-15 micrograms/ml, while the susceptible ones presented MIC values under 5 micrograms/ml. All the isolates from France, Italy, New Zealand, Sweden, USA, Poland, Czech Republic and Germany were susceptible with MIC values under 5 micrograms/ml.