Sensitivity of Paenibacillus larvae isolates against Oxytetracycline by the disc diffusion method

Paenibacillus larvae, a Gram-positive and spore-forming bacterium is responsible for American foulbrood (AFB) disease in bees. AFB is a serious economic problem for beekeepers. The extensive use of antibiotics such as Oxytetracycline (OTC) against AFB have led to the accumulation of residues in honey and other beehive products, decreasing their quality and making their marketing more difficult. Besides residue accumulation, antibiotic resistant isolates of P. larvae have been detected in many countries. In this study, in view of the increasing incidence of Antibiotic-resistant bacteria in the world, we tested OTC against 22 isolated of P. l. larvae strains from different areas for Antibiotic Susceptibility by the disk diffusion method.
Our results introduce evidence that 7 strains was very sensitive, 14 strains intermediate and 1 strain was resistant to OTC.