Alternative Approaches for Mitigation of Drug Resistance in Streptococcus Species

Document Type : Original Article


1 Department of Microbiology, Faculty of Veterinary Medicine, Zagazig University, Egypt.

2 Abou Hamad Veterinary organization, Ministry of agriculture, Abou Hamad, Sharkia, Egypt


During infection, S. agalactiae can form biofilms which is associated with increased antimicrobial resistance. Additionally, bacteria  when present in a biofilm ,are resistant to various physicochemical stresses. Therefore, this study is aimed to determine the in vitro anti biofilm activities of cinnamon oil and/or silver nanoparticles and augmentin against multidrug resistant S. agalactiae isolates recovered from clinical mastitic dairy cattle. Antimicrobial susceptibility testing of 146 Streptococci isolates revealed that 42.5% (62/146) of Streptococci isolates exhibited a feature of multidrug resistance (MDR), being resistant to more than 3 antibiotics of different classes. Cinnamon oil, silver nanoparticles and augmentin exhibited marked inhibitory activities against S. agalactiae isolates with inhibition zone diameters up to 40 mm, 35 mm and 38 mm respectively. Besides, broth microdilution test of cinnamon oil revealed maximum activities against the tested isolates with minimum inhibitory concentrations (MICs) up to 0.0025 µg/mL. The combination of cinnamon oil and silver nanoparticles combination gave the best result as the MIC values have been reduced to 4 folds. The cinnamon oil alone was capable of reducing the number of cells just after 4 h according to time killing assay.
The above results highlight the hopeful antibacterial and antibiofilm features of cinnamon oil and silver nanoparticles in the treatment of emergent resistant S. agalactiae mastitic infections.


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