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Antibacterial activity of Sage extract at concentrations of 0.1, 0.05, 0.025, 0.0125, 0.00625, 0.003125, 0.00156, 0.0005 and 0.00025 g dL(-1) against Salmonella typhi, Shigella sonnei, S. flexneri, Proteus vulgaris, Staphylococcus aureus, ETEC Escherichia coli and Pseudomonas aeruginosa was evaluated. Susceptibility testing of bacterial strains against 18 antibiotics was also performed for comparison. The results showed that P. aeruginosa and ETEC E. coli were completely resistant to Sage extract even at concentration of 0.1 g dL(-1). Its antibacterial activity (0.1 g dL(-1)) against P. vulgaris, S. flexneri and S. sonnei was the same as nitrofurantoin and ampicilline respectively. Sage extract (0.1 and 0.05 g dL(-1)) exhibited the same effects as ampicilline and streptomycin against S. typhi. Its antibacterial activity (0.1, 0.05 and 0.25 g dL(-1)) against S. aureus was the same as ceftazidim, chloramphenicol, gentamycin, neomycin and nitrofurantoin and was more significant compared to streptomycin and vancomycin. The results suggest Sage can be considered as an alternative herbal in the treatment of infections caused by the above-mentioned bacteria.

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Aim: This study is aimed at characterization of both antimicrobial and antibiofilm activity of R-pyocin from clinical Pseudomonas aeruginosa against Gram-positive pathogens including Staphylococcus aureus. Methods and Results: Pyocinogenic P. aeruginosa was detected using reverseside method, and pyocinogeny typing was confirmed using revised-spotting method. Transmission electron microscopy (TEM) was used for morphological characterization of R-pyocin and for detection of changes in membrane of Rpyocin-treated S. aureus. SDS-PAGE analysis was used for detection of the molecular weight of R-pyocin protein-subunits and Poisson-killing-distribution assay for burst-size calculation. Lipotechoic-acid (LTA) adsorption-assay was used to confirm whether LTA in Gram-positive bacteria served as R-pyocin receptor. Moreover, R-pyocin production at 10-60°C was assessed herein. Host-range of activity of R-pyocin was tested against antimicrobial resistant (AMR) pathogens. The anti-biofilm activity of R-pyocin was detected against sensitive bacterial strains. Chemical, enzymatic, pH and thermo-stability of Rpyocin were evaluated. TEM micrographs revealed a typical morphology of myotailocins indicating the production of R-pyocin designated as RPU15. TEM revealed pores formation in S. aureus membrane, and bacteriophage-like plaques were obvious on plates of R-pyocin-treated S. aureus. R-pyocin activity was neutralized by LTA of S. aureus and Listeria monocytogenes. Pseudomonas aeruginosa PU15 produced ~428 non-inducible R-pyocin particles. RPU15 sheath and tube protein-subunits exhibited a molecular weight of 38 and 23 kDa, respectively. RPU15 possessed activity against S. aureus, L. monocytogenes, Bacillus cereus and Candida albicans and reduced biofilmbiomasses of tested AMR strains. Conclusion: Our results show the potential therapeutic use of R-pyocin due to its effectiveness on tested bacterial biofilms. Significance and Impact of the Study: This is the first study that investigates antimicrobial and anti-biofilm activity of R-pyocin activity against S. aureus. R-pyocin shows new phenomenon of bacteriophage-like plaques. Our findings represent a future therapeutic agent targeting both methicillin-resistant and vancomycin-resistant S. aureus.