Staphylococcal infections are often hard to treat due to increasing resistance, especially to β-lactams. Previous studies described the synergy between common antibiotics and isoflavonoids; however, little is yet known about the combinatory effects of antibiotics with products of human isoflavone metabolism. In this study, demethyltexasin (DT), a human body metabolite of soybean isoflavones, was evaluated for its possible antistaphylococcal combinatory effect with amoxicillin and oxacillin. For comparison, common therapeutically used combination of amoxicillin/clavulanic acid was tested. DT showed strong synergistic interactions against most of Staphylococcus aureus strains when combined with amoxicillin (sum of fractional inhibitory concentrations [ΣFIC] 0.257-0.461) and oxacillin (ΣFIC 0.109-0.484). When oxacillin was combined with DT, resistance to this antibiotic was overcome in many cases. Moreover, antibiotic/DT combinations were effective mainly against methicillin-resistant S. aureus (MRSA); however, the commonly used drug amoxicillin/clavulanic acid was effective only against sensitive strains. Our results indicated DT as a compound able to act synergistically with β-lactams. In addition, some combinations are effective against MRSA and decrease staphylococcal resistance. To the best of our knowledge this is the first report of the antimicrobial synergistic effects of isoflavone human body metabolite with common antibiotics. DT seems to be a possible candidate for further research focused on antistaphylococcal drug development, especially against antibiotic-resistant strains.

• MeSH
• amoxicilin farmakologie   MeSH
• antibakteriální látky farmakologie   MeSH
• fixní kombinace léků MeSH
• isoflavony farmakologie   MeSH
• kombinace amoxicilinu a kyseliny klavulanové farmakologie   MeSH
• lidé MeSH
• methicilin rezistentní Staphylococcus aureus účinky léků   růst a vývoj   MeSH
• mikrobiální testy citlivosti MeSH
• oxacilin farmakologie   MeSH
• rezistence na methicilin účinky léků   MeSH
• Staphylococcus aureus účinky léků   růst a vývoj   MeSH
• synergismus léků MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

UNLABELLED: The need for suitable selective cultivation media for the isolation of Bifidobacterium spp. continues to be a real concern in the field of intestinal microbiology. Isolation of bifidobacteria from human and animal faecal samples using selective agar plating may be problematic especially in samples with increased clostridial counts than bifidobacterial counts. Due to the absence of anticlostridial agents in existing selective media, clostridia can displace bifidobacteria resulting in incorrect estimation of their counts. Therefore, we supplemented the existing selective medium 'modified Wilkins Chalgren agar with mupirocin' (MWM) with 90 mg l(-1) of 8-hydroxyquinoline (8HQ), which was recently proved to act selectively against clostridia. The newly composed 'modified Wilkins-Chalgren agar with 8HQ' (MWMQ) was tested on pure bifidobacterial and clostridial strains, their mixtures, and using faecal samples of mammalian origin; its selectivity was evaluated by genus-specific identification of isolates. The results demonstrated that the presence of 8HQ in this agar eliminated the growth of nonbifidobacterial strains on MWMQ compared to that on MWM, whereas the recovery of bifidobacterial counts was at satisfactory levels. In conclusion, MWMQ could be recommended for bifidobacterial isolation from human and animal faeces especially when bifidobacteria are not numerically dominant and there are chances of clostridial contamination. SIGNIFICANCE AND IMPACT OF THE STUDY: Routine isolation of bifidobacteria from mammalian faeces does not use a reliable selective agar with an anticlostridial agent. Overgrowth of clostridia may result in incorrect estimation of bifidobacterial counts. Thus, in order to improve the selectivity of existing media for bifidobacterial isolation, we chose the modified Wilkins-Chalgren agar with mupirocin and supplemented it with 8-hydroxyquinoline (8HQ), a molecule that shows anticlostridial activity without affecting the growth of bifidobacteria. This newly composed medium showed enhanced selectivity and specificity compared to the original medium and therefore, can be recommended for the isolation of bifidobacteria from mammal faeces.

• MeSH
• agar farmakologie   MeSH
• bakteriální nálož účinky léků   MeSH
• Bifidobacterium růst a vývoj   izolace a purifikace   MeSH
• Clostridium účinky léků   růst a vývoj   MeSH
• feces mikrobiologie   MeSH
• kultivační média farmakologie   MeSH
• lidé MeSH
• mupirocin farmakologie   MeSH
• oxychinolin farmakologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH