The aim of this study was to evaluate the antimicrobial activity of lapachol, α-lapachone, β-lapachone and six antimicrobials (ampicillin, amoxicillin/clavulanic acid, cefoxitin, gentamicin, ciprofloxacin and meropenem) against twelve strains of Staphylococcus aureus from which resistance phenotypes were previously determined by the disk diffusion method. Five S. aureus strains (LFBM 01, LFBM 26, LFBM 28, LFBM 31 and LFBM 33) showed resistance to all antimicrobial agents tested and were selected for the study of the interaction between β-lapachone and antimicrobial agents, busing checkerboard method. The criteria used to evaluate the synergistic activity were defined by the Fractional Inhibitory Concentration Index (FICI). Among the naphthoquinones, β-lapachone was the most effective against S. aureus strains. FICI values ranged from 0.07 to 0.5, suggesting a synergistic interaction against multidrug resistant S. aureus (MRSA) strains. An additive effect was observed with the combination β-lapachone/ciprofloxacin against the LFBM 33 strain. The combination of β-lapachone with cefoxitin showed no added benefit against LFBM 31 and LFBM 33 strains. This study demonstrated that, in general, β-lapachone combined with beta lactams antimicrobials, fluoroquinolones and carbapenems acts synergistically inhibiting MRSA strains.
The aim of this study was to evaluate the antimicrobial activity of aqueous extract of Psidium guineense Swartz (Araçá-do-campo) and five antimicrobials (ampicillin, amoxicillin/clavulanic acid, cefoxitin, ciprofloxacin, and meropenem) against twelve strains of Staphylococcus aureus with a resistant phenotype previously determined by the disk diffusion method. Four S. aureus strains showed resistance to all antimicrobial agents tested and were selected for the study of the interaction between aqueous extract of P. guineense and antimicrobial agents, by the checkerboard method. The criteria used to evaluate the synergistic activity were defined by the fractional inhibitory concentration index (FICI). All S. aureus strains were susceptible to P. guineense as determined by the microdilution method. The combination of the P. guineense extract with the antimicrobial agents resulted in an eight-fold reduction in the MIC of these agents, which showed a FICI ranging from 0.125 to 0.5, suggesting a synergistic interaction against methicillin-resistant Staphylococcus aureus (MRSA) strains. The combination of the aqueous extract of P. guineense with cefoxitin showed the lowest FICI values. This study demonstrated that the aqueous extract of P. guineense combined with beta lactamics antimicrobials, fluoroquinolones, and carbapenems, acts synergistically by inhibiting MRSA strains.
The consumption of probiotic microorganisms in fermented products has been used for centuries. Lactobacillus spp. is one of the main species studied due to its various beneficial effects on health. This species has a great ability to adapt to hostile environments, produces antimicrobial substances capable of destroying or inhibiting the growth of pathogenic bacteria, and is involved in the digestion of complex carbohydrates not digested by the host. However, there are still some uncertainties and disagreements about the precise biochemical metabolism of lactobacilli. The aim of this article is to review the metabolism and physiological characteristics of lactobacilli for a better understanding of the benefits that these bacteria promote in the host and for the development of strains and probiotic products with higher health benefits.
The consumption of probiotic microorganisms in fermented products has been used for centuries. Lactobacillus spp. is one of the main species studied due to its various beneficial effects to health. This species has great ability to adapt to hostile environments, produces antimicrobial substances capable of destroying or inhibiting the growth of pathogenic bacteria and is involved in the digestion of complex carbohydrates not digested by the host. However, there are still some uncertainties and disagreements about the precise biochemical metabolism of lactobacilli. The aim of this article is to review the metabolism and physiological characteristics of lactobacilli for a better understanding of the benefits that these bacteria promote in the host and for the development of strains and probiotic products with higher health benefits.
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