In Vitro Activity of Miltefosine against Candida albicans under Planktonic and Biofilm Growth Conditions and In Vivo Efficacy in a Murine Model of Oral Candidiasis

Abstract

The generation of a new antifungal against Candida albicans biofilms has become a major priority, since biofilm formation by this opportunistic pathogenic fungus is usually associated with an increased resistance to azole antifungal drugs and treatment failures. Miltefosine is an alkyl phospholipid with promising antifungal activity. Here, we report that, when tested under planktonic conditions, miltefosine displays potent in vitro activity against multiple fluconazole-susceptible and -resistant C. albicans clinical isolates, including isolates overexpressing efflux pumps and/or with well-characterized Erg11 mutations. Moreover, miltefosine inhibits C. albicans biofilm formation and displays activity against preformed biofilms. Serial passage experiments confirmed that miltefosine has a reduced potential to elicit resistance, and screening of a library of C. albicans transcription factor mutants provided additional insight into the activity of miltefosine against C. albicans growing under planktonic and biofilm conditions. Finally, we demonstrate the in vivo efficacy of topical treatment with miltefosine in the murine model of oropharyngeal candidiasis. Overall, our results confirm the potential of miltefosine as a promising antifungal drug candidate, in particular for the treatment of azole-resistant and biofilm-associated superficial candidiasis.T he recent elevated incidence of fungal infections is related to the indiscriminate use of broad-spectrum antibiotics and corticosteroids, the increase in the number of invasive medical procedures, and the AIDS epidemic. The persistence of these infections is usually associated with the fungal ability to form biofilms on implantable medical devices (1). Candida spp. can adhere and form biofilms on the surface of different medical devices (such as catheters, prostheses, pacemakers, and heart valves) and on the mucosal surface, leading to a superficial infection with a complex structure in which hyphae, pseudohyphae, and yeasts grow surrounded by a dense extracellular matrix, composed mainly of proteins, polysaccharides, and extracellular DNA (eDNA) (2). Hematogenous dissemination may occur due to the detachment of yeasts from the top layer of the biofilm, a phenomenon known as dispersion (3). Candida albicans is the third leading cause of infections related to the use of catheters (4, 5). Development of candidemia during hospitalization when central venous catheters are used can happen in 72% of cases in Latin America (6), and the worldwide mortality rate for catheter-related candidemia can reach 41% (7). Oropharyngeal candidiasis (OPC) is characterized by Candida growth as a biofilm over the tongue and oral mucosa. OPC has been described as the most frequent opportunistic fungal infection among HIV-positive patients, and it is estimated that more than 90% of these patients develop this infection at some time during the progression of their disease (8, 9).The increased resistance to antifungal agents is the main clinical complication associated with biofilm formation. ...

Antifungal Activity of Oleylphosphocholine on In Vitro and In Vivo Candida albicans Biofilms

“…Moreover, fungicidal activity of OlPC against C. albicans cells was reported for concentrations ranging between 2 and 4 mg/liter, which are identical to the MICs of almost all isolates tested. Interestingly, similar concentrations of OlPC were able to reduce or to completely abolish biofilm development, reminiscent of the results that were previously obtained with miltefosine (5,11). Additionally, we show that highly dense preformed biofilms can also be inactivated with OlPC at concentrations only 2 to 4 times higher than the MIC for planktonic cells.…”

“…Recently, miltefosine, an alkylphospholipid, was shown to have very good activity against C. albicans biofilms (4). It was also effective against oral candidiasis that developed on murine tongues (5). However, side effects and teratogenicity narrow the therapeutic window and limit its potential use (6,7).…”

Repositionable Compounds with Antifungal Activity against Multidrug Resistant Candida auris Identified in the Medicines for Malaria Venture’s Pathogen Box

“…Miltefosine has also been used successfully in a limited number of cases of the extremely rare highly lethal brain infection by the amoeba Naegleria fowleri and, in the United States, has orphan drug status for the treatment of other amebic infections [62]. Our group and others have previously described the antifungal activity of miltefosine [63][64][65][66][67][68]. Iodoquinol (also referred to as diiodohydroxyquinoline) is an halogenated quinoline derivative (see Supplementary Figure S1) that is used as an intestinal antiparasitic drug, mainly in the treatment of Entamoeba histolytica infections [69], apparently acting by chelation of ferrous ions essential for metabolism.…”

Screening the Pathogen Box for Identification of Candida albicans Biofilm Inhibitors

“…Fluconazole is one of the three main antifungal drugs used in the treatment of Candida infections, and for many years before the introduction of the echinocandins, it remained a first-line antifungal therapy for the treatment of candidiasis (13). However, it is well established that fluconazole is not active against preformed biofilms and can lead to treatment failure in biofilm-associated infections (5,23). Considering the fact that compound MMV688768 per se showed potent activity against preformed biofilms, we decided to evaluate if the combination of this compound with fluconazole could improve killing of C. albicans biofilms with reduced doses.…”