Evaluation of the synergistic antimicrobial activities of selenium nanoparticles and Rosemary oil against Aspergillus fumigatu and Klebsiella pneumoniae recovered from respiratory infection in cattle in Giza governorate, Egypt

: Synergistic and single antimicrobial activities of green synthesized selenium nanoparticles (SeNPs) and rosemary oil were investigated against predominant causes of respiratory diseases in cattle as Aspergillus fumigatus and Klebsiella pneumoniae . The prevalence rates of A. fumigatus were 14.28%, 12%, and 32% in the nasal swab, drinking water, and animal ration, respectively. While, Klebsiella pneumoniae was isolated from examined nasal swabs, water, and rations at the rates of 17.4%, 0%, and 8%, respectively. The minimal inhibitory concentration (MIC) of Se-NPs was 0.4 mg/ml and 0.5 mg/ml against A. fumigatus and Kl. pneumoniae , respectively. On the other hand, the inhibitory concentration of Rosemary against A. fumigatus and Kl. pneumoniae was 0.75 mg/ml and 1.0 mg/ml, respectively. The synergistic therapy of SeNPs dispersed with Rosemary oil reduced the MIC of SeNPs against A. fumigatus and Kl. pneumoniae was 0.1mg/ml and hence can be used as alternatives to their single forms in successful disease therapy. Moreover, these synergisms are essential to overcome the microbial resistance against the traditional antibiotics and decrease the concentrations used of nanoparticles to avoid their toxicity for