Anticandidal activity of SPA-S-843, a new polyenic drug

The activity of a new, soluble and stable polyene (SPA-S-843) against Candida albicans was assessed by contact and culture tests and by inhibition of germ-tube formation. The drug demonstrated a higher contact activity and lower MICs than amphotericin B. This antimicrobial activity was more evident under acid pH and low ionic strength. In addition, the ability of SPA-S-843 to inhibit Candida sp. conversion from yeast to mycelial form was evident at low drug concentrations (0.25-0.62 mg/L).     

Overview of SPA-S-843 in vitro activity against filamentous fungi

In this study, we investigated the in vitro antifungal activity of a new water-soluble partricin A derivative, N-dimethylaminoacetyl-partricin A 2-dimethylaminoethylamide diascorbate, coded SPA-843, currently developed by Società Prodotti Antibiotici. The activity of SPA-S-843 was compared to that of amphotericin B against 13 strains of Aspergillus spp., 4 strains of Mucor sp., 4 strains of Rhizopus oryzae, 2 strains Paecilomyces variotii, 5 strains of Penicillium spp., 1 strain of Sporothrix schenkii, 7 strains of Trichophyton spp. and 2 strains of Microsporum spp.; the minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) were measured for all the organisms. The in vitro susceptibility testing method employed was an adaptation of the macrodilution reference method for yeasts as described in the National Committee for Clinical Laboratory Standards document M27-A. The in vitro inhibitory activities of SPA-S-843 and amphotericin B against the fungi were evaluated in RPMI-1640 supplemented with L-glutamine and buffered with morpholinepropanesulfonic acid, while the in vitro fungicidal activities were determined by subculturing 0.1 ml from all tubes with no visible growth onto drug-free Sabouraud dextrose agar plates. Comparison with amphotericin B showed that the in vitro inhibitory activity of SPA-S-843 against Aspergillus spp. was better than that of amphotericin B and similar against R. oryzae, P. variotii, Penicillium spp. and S. schenkii. Amphotericin B presented geometric means (GM) of the MICs lower than those of SPA-S-843 against Mucor sp., Microsporum spp. and Trichophyton spp. SPA-S-843 was most fungicidal against Mucor sp. and P. variotii; SPA-S-843 and amphotericin B showed the same fungicidal activity against Aspergillus spp. (GM of the MFCs 12.53 microg/ml), Penicillium spp. (about 12 microg/ml) and S. schenkii (MFC 19.2 microg/ml). Amphotericin B presented GM of the MFC values lower than those of SPA-S-843 against R. oryzae, Microsporum spp. and Trichophyton spp.     

Efficacy of the partricin derivative SPA-S-753 against systemic murine candidosis

The polyene partricin compound SPA-S-753 (Societa Prodotti Antibiotici, Milano, Italy) was assessed in a murine model of systemic candidosis. CD-1 mice were infected iv with Candida albicans and treated iv with SPA-S-753 or amphotericin B. All treatment regimens of SPA-S-753 or amphotericin B were equivalent and significantly prolonged survival compared with controls (P < 0.001). Amphotericin B and SPA-S-753 significantly reduced burdens of C. albicans in the spleen and kidneys. Overall, cure rates were similar, amphotericin B at 1 mg/kg cured three and SPA-S-753 at 10 mg/kg cured four mice of infection in both organs. The efficacy of SPA-S-753 is between equivalent and <10-fold as potent as amphotericin B. These results are encouraging and warrant further studies on SPA-S-753.     

Caspofungin at Catheter Lock Concentrations Eradicates Mature Biofilms of Candida lusitaniae and Candida guilliermondii

The antibiofilm activities of caspofungin, anidulafungin, micafungin, and liposomal amphotericin B were studied against Candida lusitaniae, Candida guilliermondii, and a Candida albicans control strain. While anidulafungin and micafungin (0.007 to 2,048 mg/liter) showed reduced activity against biofilms of both test species, caspofungin displayed concentration-dependent antibiofilm activity, reaching complete and persistent eradication at concentrations achievable during lock therapy (512 to 2,048 mg/liter, P < 0.05). Although liposomal amphotericin B strongly inhibited mature biofilms, it possessed lower antibiofilm activity than caspofungin (P < 0.05).     

In vitro efficacy of 5 antifungal agents against Candida parapsilosis,Candida orthopsilosis, and Candida metapsilosis as determined by time–kill methodology

Killing activity of amphotericin B, fluconazole, voriconazole, posaconazole, and 5-fluorocytosine was determined against 6 Candida parapsilosis, 3 Candida orthopsilosis, and 4 Candida metapsilosis clinical isolates. After 24 h, 1 of 6 C. parapsilosis, 1 of 3 C. orthopsilosis, and 3 of 4 C. metapsilosis isolates were killed at 1 to 4 μg/mL (1–8× MIC) amphotericin B. The remaining isolates were killed by 2 to 4 μg/mL amphotericin B after 48 h. Fluconazole was fungistatic at ≥1× MIC (0.5–2 μg/mL) against C. parapsilosis and at ≥2× MIC (4–8 μg/mL) against C. orthopsilosis and C. metapsilosis isolates. Voriconazole inhibited C. parapsilosis at ≥1× MIC (0.015–0.12 μg/mL), but the other 2 species were inhibited only at 4 to 8× MIC (0.25–0.5 μg/mL). Against C. orthopsilosis and C. metapsilosis, posaconazole was fungistatic close to the MIC (0.03–0.06 and 0.015–0.03 μg/mL, respectively). Against C. orthopsilosis and C. metapsilosis, fluconazole and voriconazole, but not posaconazole, seem to be less active in vitro than against C. parapsilosis.     

In Vitro Activities of Voriconazole (UK-109,496) and Four Other Antifungal Agents against 394 Clinical Isolates of Candida spp.

Voriconazole (formerly UK-109,496) is a new monotriazole antifungal agent which has potent activity against Candida, Cryptococcus, and Aspergillus species. We investigated the in vitro activity of voriconazole compared to those of fluconazole, itraconazole, amphotericin B, and flucytosine (5FC) against 394 bloodstream isolates of Candida (five species) obtained from more than 30 different medical centers. MICs of all antifungal drugs were determined by the method recommended by the National Committee for Clinical Laboratory Standards using RPMI 1640 test medium. Overall, voriconazole was quite active against all the yeast isolates (MIC at which 90% of the isolates are inhibited [MIC₉₀], ≤0.5 μg/ml). Candida albicans was the most susceptible species (MIC₉₀, 0.06 μg/ml) and Candida glabrata and Candida krusei were the least (MIC₉₀, 1 μg/ml). Voriconazole was more active than amphotericin B and 5FC against all species except C. glabrata and was also more active than itraconazole and fluconazole. For isolates of Candida spp. with decreased susceptibility to fluconazole and itraconazole MICs of voriconazole were also higher. Based on these results, voriconazole has promising antifungal activity and further in vitro and in vivo investigations are warranted.     

In vitro activity of A-192411.29, a novel antifungal lipopeptide

A-192411.29 is a novel antifungal agent derived from the structural template of the natural product echinocandin. The in vitro activity of A-192411.29 against common pathogenic yeasts was assessed by National Committee for Clinical Laboratory Standards method M27-A. It demonstrated broad-spectrum, fungicidal activity and was active against the most clinically relevant yeasts, such as Candida albicans, Candida tropicalis, and Candida glabrata, as well as less commonly encountered Candida species; in general, its potency on a weight basis was comparable to that of amphotericin B. It maintained potent in vitro activity against Candida strains with reduced susceptibilities to fluconazole and amphotericin B. The in vitro activity of A-192411.29 against Cryptococcus neoformans was comparable to its activity against Candida spp. However, A-192411.29 did not demonstrate complete growth inhibition of Aspergillus fumigatus by the broth microdilution method used. A-192411.29 possesses an antifungal profile comparable to or better than those of fluconazole and amphotericin B against pathogenic yeasts, including strains resistant to fluconazole or amphotericin B, suggesting that it may be a therapeutically useful new antifungal drug.     

In vitro antifungal activity of BMS-181184 against systemic isolates of Candida,Cryptococcus, and Blastomyces species

BMS-181184 is a water-soluble derivative of the pradimicin group of antifungal compounds. We determined the in vitro activities of BMS-181184 and comparator agents amphotericin B, 5-fluorocytosine, fluconazole, and ketoconazole against 184 systemic fungal isolates collected at the Health Sciences Centre in Winnipeg, Canada, between 1987 and 1995. BMS-181184 demonstrated MICs of between 1 and 8 μg/mL for all Candida albicans, Candida glabrata, Candida tropicalis, Candida krusei, Candida lusitaniae, and Cryptococcus neoformans isolates tested. BMS-181184 was less active against Candida parapsilosis (MIC₉₀ = 16 μg/mL) and Blastomyces dermatitidis (MIC₉₀ = 32 μg/mL). Isolates of Candida species with fluconazole MICs of ≥16 μg/mL and those with fluconazole MICs of ≤8 μg/mL demonstrated similar BMS-181184 sensitivities.     

Effect of aqueous extract of date palm fruit (<Emphasis Type="Italic">Phoenix dactylifera</Emphasis> L.) on therapeutic index of amphotericin B

The aim of this study was to identify the effect of aqueous extract of date palm fruit (Phoenix dactylifera L.) on therapeutic index of amphotericin B. The water extract of date fruit of Phoenix dactylifera were tested for the antifungal activity with amphotericin B against the yeast Candida albicans ATCC 1023. Secondly, we have tested the cytotoxicity of this complex on human red blood cells.The results showed a significant improvement in the antifungal activity compared with amphotericin B alone at therapeutic concentration. Furthermore, the addition of aqueous extract protects human red blood cells against the cytotoxicity induced by amphotericin B. This is due probably, to the effect of flavonoïds and polysaccharides present in date fruit.     

In vitro interaction of fluconazole and amphotericin B administered sequentially against Candida albicans: effect of concentration and exposure time

This study investigated the potential antagonism of fluconazole on amphotericin B activity against Candida albicans when administered sequentially in vitro. Yeast cells were exposed to fluconazole for time periods ranging from 0 to 24 h before the addition of amphotericin B. The combination showed fungicidal (≥3 log₁₀ reduction in CFU/mL) activity. After 4 h of exposure to fluconazole, amphotericin B activity was partially inhibited at the lower concentration tested (0.25 × MIC). Amphotericin B activity was dramatically decreased by previous exposure to fluconazole for greater than or equal to 8 h at both the high and low concentrations tested. The activity of amphotericin B against yeast exposed to fluconazole for at least 8 h was indistinguishable from fluconazole alone and was fungistatic (≤2 log₁₀ reduction in CFU/mL). This inhibition of amphotericin B activity persisted for a very short period (<6 h) after removal of fluconazole from the culture medium, indicating the need for continued exposure to fluconazole for lasting inhibition of amphotericin B activity.     

Combined Activity of Minocycline and Amphotericin B In Vitro Against Medically Important Yeasts

The capacity of minocycline to enhance the activity of amphotericin B against Candida albicans, Torulopsis glabrata, Cryptococcus neoformans, and non-albicans Candida was examined in vitro utilizing a time-killing curve technique. Synergism was apparent at 4 h with 5 of 5 strains of C. albicans, 8 of 8 strains of C. neoformans, and 1 of 12 strains of non-albicans Candida. Synergism was apparent at 24 h with the remaining 11 strains of non-albicans Candida and all 5 strains of T. glabrata. C. neoformans was the most susceptible of the yeasts to the minocycline-amphotericin B combination; seven strains showed a 3-log or greater reduction in colony count in 4 h and all strains showed this reduction in 24 h at amphotericin B concentrations of 0.4 μg/ml or less in the presence of minocycline.     

In Vitro Interactions of Antifungal Agents and Tacrolimus against Aspergillus Biofilms

Aspergillus biofilms were prepared from Aspergillus fumigatus, Aspergillus flavus, and Aspergillus terreus via a 96-well plate-based method, and the combined antifungal activity of tacrolimus with azoles or amphotericin B against Aspergillus biofilms was investigated via a broth microdilution checkerboard technique system. Our results suggest that combinations of tacrolimus with voriconazole or amphotericin B have synergistic inhibitory activity against Aspergillus biofilms. However, combinations of tacrolimus with itraconazole or posaconazole exhibit no synergistic or antagonistic effects.     

In Vitro Antifungal Activities of a Series of Dication-Substituted Carbazoles,Furans, and Benzimidazoles

Aromatic dicationic compounds possess antimicrobial activity against a wide range of eucaryotic pathogens, and in the present study an examination of the structures-functions of a series of compounds against fungi was performed. Sixty-seven dicationic molecules were screened for their inhibitory and fungicidal activities against Candida albicans and Cryptococcus neoformans. The MICs of a large number of compounds were comparable to those of the standard antifungal drugs amphotericin B and fluconazole. Unlike fluconazole, potent inhibitory compounds in this series were found to have excellent fungicidal activities. The MIC of one of the most potent compounds against C. albicans was 0.39 μg/ml, and it was the most potent compound against C. neoformans (MIC, ≤0.09 μg/ml). Selected compounds were also found to be active against Aspergillus fumigatus, Fusarium solani, Candida species other than C. albicans, and fluconazole-resistant strains of C. albicans and C. neoformans. Since some of these compounds have been safely given to animals, these classes of molecules have the potential to be developed as antifungal agents.The incidence of fungal infections in the immunocompromised population has significantly increased over the past two decades. Frequent infections caused by molds which may be primarily resistant to azoles and azole-resistant isolates of Candida albicans and Cryptococcus neoformans, which have developed recently, have increasingly been reported (7, 13, 23, 30). In light of these developments, new antifungal agents with various mechanisms of action and fungicidal activities are needed for the effective management of these clinically important infections.Recently, we reported on the antifungal activities of analogues and metabolites of pentamidine and a series of dicationic substituted bis-benzimidazoles (11). Those in vitro studies uncovered a number of compounds with potent activity against C. albicans and C. neoformans. Several compounds were found to have inhibitory activity against these two fungi more potent than that of either fluconazole or amphotericin B. In addition, the dicationic molecules, unlike fluconazole, proved to have potent fungicidal activity, with the most potent compounds having minimum fungicidal concentrations (MFCs) below 1.0 μg/ml. These initial studies also found that dicationic molecules were effective against Aspergillus fumigatus, Fusarium solani, several Candida species other than C. albicans, and fluconazole-resistant strains of C. albicans and C. neoformans.On the basis of the initial promising results reported above, the current work expands our studies on the antifungal activities of dication-substituted molecules by screening 67 additional compounds against C. albicans and C. neoformans. The criteria used to choose the structures for the current studies were based on years of testing dicationic molecules against the fungus Pneumocystis carinii in a rat model of disease (5, 14, 17, 18, 24, 26–28). Compounds in the current studies include molecules with the cationic moieties linked by carbazole, furan, and benzimidazole bridges. In addition to screening all compounds against C. albicans and C. neoformans, selected compounds were tested against other yeasts, molds, and azole-resistant strains of C. albicans and C. neoformans.     

Activity of Liposomal Amphotericin B with Prolonged Circulation in Blood versus Those of AmBisome and Fungizone against Intracellular Candida albicans in Murine Peritoneal Macrophages

Activity against intracellular Candida albicans was assessed in C. albicans-infected murine peritoneal macrophages exposed to long-circulating pegylated amphotericin B liposomes (PEG-AMB-LIP), AmBisome, or Fungizone. The level of antifungal activity of Fungizone is much higher than that of AmBisome or PEG-AMB-LIP, while PEG-AMB-LIP and AmBisome show equivalent activity levels. Previous exposure of uninfected macrophages to PEG-AMB-LIP or AmBisome is advantageous for intracellular antifungal activity.     

In vitro pharmacodynamic characteristics of amphotericin B, caspofungin, fluconazole, and voriconazole against bloodstream isolates of infrequent Candida species from patients with hematologic malignancies

Time-kill and postantifungal effect (PAFE) of amphotericin B, caspofungin, fluconazole, and voriconazole were determined against clinical isolates of Candida guilliermondii, Candida kefyr, and Candida lusitaniae. Azoles displayed fungistatic activity and no measurable PAFE, regardless of the concentration tested. Amphotericin B and caspofungin demonstrated concentration-dependent fungicidal activity, although amphotericin B only produced a significant dose-dependent PAFE against all isolates tested.     

évaluation de l’activité antifongique de différents extraits de la cannelle de Chine (Cinnamomum cassia)

The incidence of invasive fungal infections due to Candida albicans has dramatically increased since 25 years. The amphotericin B remains the best treatment despite its severe toxicity. Our work is inscribed in the frame of finding of new natural antifungals agents from a condiment widely used in our diet: the Chinese cinnamon (Cinnamomum cassia). This study is focused on the qualitative determination of different families of secondary metabolites from the bark of Cinnamon. It is also focused on assessing the antifungal activity of some extracts of Cinnamon. The plant material was extracted by exhaustion using increased polarity solvents (chloroform, ethyl acetate, methanol and water). We made five exhaustions for each solvent, each one was tested separately. The phytochemical study revealed the presence of terpenes, alkaloids and polyphenols mainly represented by flavonoids. Evaluation of antimicrobial activity of the various extracts was carried out against references yeasts strains Candida albicans ATCC 10231 and Candida albicans 444IP. Results showed that in the exception of aqueous extracts, all other extracts have an interesting activity, with inhibition zone diameters between 19 and 60 mm for the chloroform extract. Similar results were obtained for the other organic extracts. Indeed, extracts obtained from low or medium polarity solvents are the most active. In addition, the MIC and MFC of the first fraction of the chloroform extract were respectively 0.10 and 0.20 μg/ml against Candida albicans ATCC 10231. They remain lower than those of amphotericin B against the same strain (MIC = 0.2 μg/ml and MFC = 0.4 μg/ml).     

Susceptibility of fluconazole-resistant clinical isolates of Candida spp. to echinocandin LY303366, itraconazole and amphotericin B

The in vitro activity of LY303366 was compared with those of itraconazole and amphotericin B against 156 fluconazole-resistant (MIC > or = 16 mg/L) clinical isolates of CANDIDA: spp. An adaptation of the NCCLS reference method was employed for determination of MICs. LY303366 was more potent than either itraconazole or amphotericin B against Candida albicans, Candida glabrata, Candida krusei and Candida tropicalis, even against isolates with itraconazole MICs > or = 1 mg/L. LY303366 was less potent in vitro against Candida parapsilosis and Candida guilliermondii isolates. LY303366 has promising antifungal activity and warrants further investigation.     

Activities of Fluconazole,Caspofungin, Anidulafungin,and Amphotericin B on Planktonic and Biofilm Candida Species Determined by Microcalorimetry

We investigated the activities of fluconazole, caspofungin, anidulafungin, and amphotericin B against Candida species in planktonic form and biofilms using a highly sensitive assay measuring growth-related heat production (microcalorimetry). C. albicans, C. glabrata, C. krusei, and C. parapsilosis were tested, and MICs were determined by the broth microdilution method. The antifungal activities were determined by isothermal microcalorimetry at 37°C in RPMI 1640. For planktonic Candida, heat flow was measured in the presence of antifungal dilutions for 24 h. Candida biofilm was formed on porous glass beads for 24 h and exposed to serial dilutions of antifungals for 24 h, and heat flow was measured for 48 h. The minimum heat inhibitory concentration (MHIC) was defined as the lowest antifungal concentration reducing the heat flow peak by ≥50% (≥90% for amphotericin B) at 24 h for planktonic Candida and at 48 h for Candida biofilms (measured also at 24 h). Fluconazole (planktonic MHICs, 0.25 to >512 μg/ml) and amphotericin B (planktonic MHICs, 0.25 to 1 μg/ml) showed higher MHICs than anidulafungin (planktonic MHICs, 0.015 to 0.5 μg/ml) and caspofungin (planktonic MHICs, 0.125 to 0.5 μg/ml). Against Candida species in biofilms, fluconazole''s activity was reduced by >1,000-fold compared to its activity against the planktonic counterparts, whereas echinocandins and amphotericin B mainly preserved their activities. Fluconazole induced growth of planktonic C. krusei at sub-MICs. At high concentrations of caspofungin (>4 μg/ml), paradoxical growth of planktonic C. albicans and C. glabrata was observed. Microcalorimetry enabled real-time evaluation of antifungal activities against planktonic and biofilm Candida organisms. It can be used in the future to evaluate new antifungals and antifungal combinations and to study resistant strains.     

In Vitro Studies with Ambruticin, a New Antifungal Antibiotic

The in vitro antifungal inhibitory activities of ambruticin and of various antifungal drugs of choice against 190 fungal pathogens representative of the major human mycoses were compared using a modification of the ICS agar dilution technique. Ambruticin compared favorably with amphotericin B and miconazole when tested against the dimorphic pathogens Coccidioides immitis, Histoplasma capsulatum, and Blastomyces dermatitidis and against Aspergillus fumigatus. Miconazole was the most active compound against Sporothrix schenckii, Allescheria (Petriellidium) boydii, and selected dematiaceous fungi, with ambruticin giving minimal inhibitory, concentrations from 3- to 74-fold higher. Ambruticin compared unfavorably with amphotericin B and 5-fluorocytosine when tested against Candida and Torulopsis species. Ambruticin was not as active in vitro as tolnaftate when tested against the three genera of dermatophytic fungi, but compared favorably with miconazole.     

Single-Dose Pharmacodynamics of Amphotericin B against Aspergillus Species in an In Vitro Pharmacokinetic/Pharmacodynamic Model

Conventional MIC testing of amphotericin B results in narrow MIC ranges challenging the detection of resistant strains. In order to discern amphotericin B pharmacodynamics, the in vitro activity of amphotericin B was studied against Aspergillus isolates with the same MICs by using a new in vitro pharmacokinetic/pharmacodynamic (PK/PD) model that simulates amphotericin B human plasma levels. Clinical isolates of Aspergillus fumigatus, A. terreus, and A. flavus with the same Clinical and Laboratory Standards Institute modal MICs of 1 mg/liter were exposed to amphotericin B concentrations following the plasma concentration-time profile after single-bolus administration with C_max values of 0.6, 1.2, 2.4, and 4.8 mg/liter. Fungal growth was monitored for up to 72 h based on galactomannan production. Complete growth inhibition was observed only against A. fumigatus with amphotericin B with a C_max of ≥2.4 mg/liter. At the lower C_max values 0.6 and 1.2 mg/liter, significant growth delays of 34 and 52 h were observed, respectively (P < 0.001). For A. flavus, there was no complete inhibition but a progressive growth delay of 1 to 50 h at an amphotericin B C_max of 0.6 to 4.8 mg/liter (P < 0.001). For A. terreus, the growth delay was modest (up to 8 h) at all C_maxs (P < 0.05). The C_max (95% confidence interval) associated with 50% activity for A. fumigatus was 0.60 (0.49 to 0.72) mg/liter, which was significantly lower than for A. flavus 3.06 (2.46 to 3.80) mg/liter and for A. terreus 7.90 (5.20 to 12.29) mg/liter (P < 0.001). A differential in vitro activity of amphotericin B was found among Aspergillus species despite the same MIC in the order A. fumigatus > A. flavus > A. terreus in the in vitro PK/PD model, possibly reflecting the different concentration- and time-dependent inhibitory/killing activities amphotericin B exerted against these species.