Potent In Vitro Synergism of Fluconazole and Berberine Chloride against Clinical Isolates of Candida albicans Resistant to Fluconazole

Abstract

In vitro interaction of fluconazole and berberine chloride was investigated against 40 fluconazole-resistant clinical isolates of Candida albicans. Synergism in fungistatic activity was found with the checkerboard microdilution assay. The findings of agar diffusion tests and time-kill curves confirmed the synergistic interaction, but no antagonistic action was observed.Candida albicans is the most common candidal pathogen, causing mucosal and invasive infections (7,9,23,29). With the increasing clinical use of fluconazole, a choice for the treatment of C. albicans infections (3, 5, 12), fluconazole-resistant isolates are occurring more frequently (2,19,28). Attempts have been made to cope with treatment failures by using combination therapy (14). However, contradictory results of either synergic or antagonistic actions in various antifungal combinations have been reported (8,11,16,27). As for fluconazoleresistant C. albicans, few data are available about the synergism of fluconazole with other antifungal agents (1,4,25).Berberine, a bioactive herbal ingredient, was demonstrated to have weak activity against C. albicans and C. glabrata (17,21,26). Recently, berberine was combined with amphotericin B to treat disseminated candidiasis in mice (10). To seek a novel combination therapy, we investigated the in vitro interaction of fluconazole and berberine chloride (BBR) against fluconazoleresistant clinical isolates of C. albicans.Strains and agents. Forty clinical isolates of fluconazoleresistant C. albicans were used in this study, and C. albicans ATCC 90028 was used as a quality control. Drugs prepared in dimethyl sulfoxide (DMSO) included fluconazole (PfizerRoerig Pharmaceuticals, New York, NY) and BBR (SigmaAldrich, St. Louis, MO).Checkerboard microdilution assay. Assays were performed on all 40 isolates according to methods of the CLSI (formerly NCCLS) (M27-A) (6, 18). The initial concentration of fungal suspension in RPMI 1640 medium was 10 3 CFU/ml, and the final concentrations ranged from 0.125 to 64 g/ml for fluconazole and 1 to 32 g/ml for BBR. Plates were incubated at 35°C for 24 h. Optical density was measured at 630 nm, and background optical densities were subtracted from that of each well. Each isolate was tested in triplicate. MIC 80 and MIC 50 were determined as the lowest concentration of the drugs (alone or in combination) that inhibited growth by 80% or 50%, respectively, compared with that of drug-free wells. The fractional inhibitory concentration (FIC) index is defined as the sum of the MIC of each drug when used in combination divided by the MIC of the drug used alone. Synergy and antagonism were defined by FIC indices of Յ0.5 and Ͼ4, respectively. An FIC index result of Ͼ0.5 but Յ4 was considered indifferent (20).Agar diffusion test. C. albicans 0304103 (one fluconazole-resistant isolate with a MIC of Ͼ32 g/ml for BBR) was tested by agar diffusion assay. A 100-l aliquot of 10 6 -CFU/ml suspension was spread uniformly onto the yeast extract-peptone-dextrose agar plate with or without 64 g/ml ...

Effects of Acridine Derivatives on Ca2+ Uptake by Candida albicans

“…On the other hand, these findings open the frequent possibility used in therapeutics of combining any of the more effective agents found with another agent, perhaps an antifungal, as already explored by Gamarra et al [26][27][28] Out of the three more effective, quinacrine may be a good therapeutic candidate, since it showed a small toxicity and few lateral effects during its use against malaria for many years. On the other hand, nonyl acridine orange, although not knowing its toxicity, might be tried as a local agent against candidiasis.…”

“…Gamarra et al [26] have proposed use of amiodarone, which stimulates Ca 2+ uptake, combined with fluconazole as a possible antifungal treatment against Candida albicans, even for a strain resistant to the antifungal. A similar therapeutic approach was also suggested for methylene blue by Schirmer et al [27,28]. According to a general mechanism proposal, it was decided to evaluate a group of acridine derivatives, to verify whether it can or cannot be applied.…”

Sensitization of Candida albicans to terbinafine by berberine and berberrubine

“…Previous studies have reported that berberine in combination with fluconazole or miconazole showed a synergistic antifungal activity against C. albicans with larger inhibition zones in the agar diffusion tests (29)(30)(31). In order to evaluate the sensitivity of C. albicans to the combination of terbinafine and berberine or berberrubine, agar diffusion assays were conducted to determine their inhibition zones on the agar Figure 2.…”

In Vivo and in Vitro Study on Drug-Drug Interaction of Lovastatin and Berberine from Pharmacokinetic and HepG2 Cell Metabolism Studies

“…Berberine is an alkaloid available from the medicinal plant Coptis chinensis that is widely used clinically in the treatment of gastrointestinal infections, diabetes, hypertension, and hypercholesterolemia. There are numeros drug-drug interaction studies related to berberine with Chinese medicine or drugs such as Jiao-Tai-Wan, verapamil, flavonoids of radix Scutellariae, digoxin, simvastatin, ciprofloxacin, fluconazole, doxorubicin, pravastatin, rhein, cyclosporine A, ketoconazole, losartan, probenecid, cloxacillin, midazolam, quinidine and atorvastatin [16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Combination of simvastatin with berberine improves the lipid-lowering efficacy [20].…”