Browsing by Author "Kikhney, Judith"
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- Effect of Quorum Sensing Molecule Farnesol on Mixed Biofilms of Candida albicans and Staphylococcus aureusPublication . Gaálová-Radochová, Barbora; Kendra, Samuel; Jordao, Luisa; Kursawe, Laura; Kikhney, Judith; Moter, Annette; Bujdáková, HelenaThe natural bioactive molecule farnesol (FAR) is widely studied mainly for its antibiofilm and antimicrobial properties. In addition, it increases the effectiveness of some antimicrobial substances, which makes it interesting for the development of combined therapy. In the present work, the effect of FAR either alone or in combination with oxacillin (OXA) on mixed biofilms formed by clinically relevant pathogens, Candida albicans and Staphylococcus aureus, was studied. S. aureus isolates used for biofilm formation originated from blood cultures and central venous catheters (CVC) were characterized in terms of antimicrobial resistance. The minimal biofilm inhibitory concentration (MBIC50) for FAR of 48 h mixed biofilms formed by the C. albicans and methicillin-sensitive S. aureus (MSSA) was determined to be 125 M, and for the mixed biofilms with methicillin-resistant S. aureus (MRSA) was determined to be 250 M. Treatment of mixed biofilms with OXA (2 mg/mL) showed 4% inhibition; however, the combination of OXA (2 mg/mL) and FAR (300 M) resulted in 80% inhibition of biofilms. In addition, planktonic cells of S. aureus exhibited an increased susceptibility to OXA, cefoxitin and kanamycin in the presence of FAR (150 and 300 M). Scanning electron microscopy (SEM) micrographs confirmed patchy biofilm and lack of candidal hyphae in the samples treated with FAR and FAR/OXA in comparison to control and mixed biofilms treated only with OXA. Intriguingly, in a pilot experiment using fluorescence in situ hybridization (FISH), considerable differences in activity (as indicated by ribosome content) of staphylococcal cells were detected. While the activity rate of the staphylococci in mixed biofilms treated with FAR was high, no FISH-positive signal for staphylococcal cells was found in the biofilm treated with FAR/OXA.
- Evaluating efficacy of antimicrobial and antifouling materials for urinary tract medical devices: challenges and recommendationsPublication . Ramstedt, Madeleine; Ribeiro, Isabel A.C.; Bujdakova, Helena; Mergulhão, Filipe J.M.; Jordao, Luisa; Thomsen, Peter; Alm, Martin; Burmølle, Mette; Vladkova, Todorka; Can, Fusun; Reches, Meital; Riool, Martijn; Barros, Alexandre; Reis, Rui L; Meaurio, Emilio; Kikhney, Judith; Moter, Annette; Zaat, Sebastian A.J.; Sjollema, JelmerIn Europe, the mean incidence of urinary tract infections in intensive care units is 1.1 per 1000 patient-days. Of these cases, catheter-associated urinary tract infections (CAUTI) account for 98%. In total, CAUTI in hospitals is estimated to give additional health-care costs of £1-2.5 billion in the United Kingdom alone. This is in sharp contrast to the low cost of urinary catheters and emphasizes the need for innovative products that reduce the incidence rate of CAUTI. Ureteral stents and other urinary-tract devices suffer similar problems. Antimicrobial strategies are being developed, however, the evaluation of their efficacy is very challenging. This review aims to provide considerations and recommendations covering all relevant aspects of antimicrobial material testing, including surface characterization, biocompatibility, cytotoxicity, in vitro and in vivo tests, microbial strain selection, and hydrodynamic conditions, all in the perspective of complying to the complex pathology of device-associated urinary tract infection. The recommendations should be on the basis of standard assays to be developed which would enable comparisons of results obtained in different research labs both in industry and in academia, as well as provide industry and academia with tools to assess the antimicrobial properties for urinary tract devices in a reliable way.