Honey as a Strategy to Fight Candida tropicalis in Mixed-Biofilms with Pseudomonas aeruginosa

Abstract

Fungal contaminations with Candida species are commonly responsible for several infections, especially when associated to bacteria. The therapeutic approach commonly used is being compromised due to microbial resistances of these microorganisms to antimicrobial agents, especially in biofilm. The use of honey as an antimicrobial agent has been emerging as a valuable solution and proving its potential in planktonic and in biofilm cells. This work aims to assess the effect of different honeys on biofilms of Candida tropicalis and Pseudomonas aeruginosa. The effect of Portuguese heather (PH) and manuka honeys on planktonic growth of Candida was initially evaluated by determination of the minimum inhibitory concentrations (MIC). Then, the same effect was evaluated in mixed biofilms, by colony-forming units numeration and fluorescence microscopy. The combinations of honey plus fluconazole and gentamicin were also tested. The results showed that the honeys tested enabled a great reduction of C. tropicalis, both in planktonic (12.5% and 25% of MIC for PH and manuka) and in biofilm. In polymicrobial biofilms, the use of PH and manuka honeys was revealed to be a promising choice and an alternative treatment, since they were able to reduce cells from both species. No synergistic effect was observed in antimicrobial combinations assays against polymicrobial biofilms.

Antifungal Activity of a Medical-Grade Honey Formulation against Candida auris

“…Increasing the concentration of honey from 16% to 40% led to a 2-log reduction in the CFU of C. auris , while the CFUs of the other Candida species were also reduced by 1- to 4-log, with C. glabrata being least susceptible and C. krusei most susceptible. As previous studies found differences in the susceptibility of yeasts to different types of honey [ 11 , 12 , 13 ], the five Candida species were also treated with a local unprocessed honey. Local unprocessed honey (40%) caused a 2- to 5-log reduction in all Candida species.…”

“…A promising candidate for the treatment of yeasts in wounds and skin colonization is honey. Medical-grade honey follows strict criteria to guarantee its safety, quality, and efficacy, and was also found to be effective in inhibiting different Candida species, such as C. albicans and C. tropicalis [ 10 , 11 , 12 , 13 ]. Medical-grade honey consists of more than 200 different components influenced by its botanical origin, geographical location and secretions from the bee [ 14 ].…”

Pathogenesis and Clinical Relevance of Candida Biofilms in Vulvovaginal Candidiasis

“…The derivatives of flavonoids, such as methylated isoflavones (i.e., formononetin 7- O -apiosyl glucoside) ( Martins et al, 2016 ), or the polyphenol, licochalcone-A, found in the roots of Glycyrrhiza spp. ( Seleem et al, 2016 ) or honey ( Fernandes et al, 2020 ), have also been demonstrated to be useful.…”

Antibiofilm Activity of Heather and Manuka Honeys and Antivirulence Potential of Some of Their Constituents on the DsbA1 Enzyme of Pseudomonas aeruginosa

“…Heather honey has been the subject of a limited number of studies investigating its effect on bacterial biofilms. Only one study to date has reported its inhibitory activity on mixed Candida–Pseudomonas biofilms [ 40 ]. This prompted us to test its activity against a range of Gram-positive and Gram-negative single-species biofilms.…”

“…Both honeys have demonstrated antibacterial activity [ 36 , 38 , 39 ] and an inhibitory effect on polymicrobial biofilms [ 40 ]. Manuka honey can disrupt biofilm formation in several pathogens [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ].…”