In vitro studies of a new antifungal triazole, D0870, against Candida albicans, Cryptococcus neoformans, and other pathogenic yeasts

The Interkingdom Interaction with Staphylococcus Influences the Antifungal Susceptibility of the Cutaneous Fungus Malassezia

The skin is a dynamic ecosystem on which diverse microbes reside. The interkingdom interaction between microbial species in the skin microbiota is thought to influence the health and disease of the skin although the roles of the intra- and interkingdom interactions remain to be elucidated. In this context, the interactions between Malassezia and Staphylococcus, the most dominant microorganisms in the skin microbiota, have gained attention. This study investigated how the interaction between Malassezia and Staphylococcus affected the antifungal susceptibility of the fungus to the azole antifungal drug ketoconazole. The susceptibility was significantly decreased when Malassezia was co-cultured with Staphylococcus. We found that acidification of the environment by organic acids produced by Staphylococcus influenced the decrease of the ketoconazole susceptibility of M. restricta in the co-culturing condition. Furthermore, our data demonstrated that the significant increased ergosterol content and cell membrane and wall thickness of the M. restricta cells grown in the acidic environment may be the main cause of the altered azole susceptibility of the fungus. Overall, our study suggests that the interaction between Malassezia and Staphylococcus influences the antifungal susceptibility of the fungus and that pH has a critical role in the polymicrobial interaction in the skin environment.

Impact of pH on the antifungal susceptibility of vaginal Candida albicans

OBJECTIVE

To investigate the antifungal susceptibility at pH 7.0 and pH 4.0 of 5 antifungal agents against Candida albicans isolated from patients with vulvovaginal candidiasis.

METHODS

Antifungal susceptibility testing at pH 7.0 and pH 4.0 was performed using the broth microdilution method (CLSI, document M27-A2).

RESULTS

The minimal inhibitory concentrations (MICs) of miconazole, clotrimazole, fluconazole, and nystatin against C. albicans at pH 4.0 were significantly higher than those at pH 7.0 (0.25 vs 0.03 μg/mL, 0.50 vs 0.03 μg/mL, 0.50 vs 0.25 μg/mL, and 32 vs 2 μg/mL, respectively; P<0.001), whereas the MIC of itraconazole at pH 4.0 was lower than that at pH 7.0 (0.030 vs 0.125 μg/mL; P<0.001). The susceptibility rate of C. albicans to itraconazole at pH 4.0 was significantly higher than at pH 7.0 (95.0% vs 51.7%; P<0.001). The susceptibility rate to itraconazole at pH 7.0 was significantly lower than the susceptibility rate to fluconazole (51.7% vs 100.0%; P<0.001), whereas the susceptibility rates to the 2 drugs were similar at pH 4.0 (95.0% and 96.7%, respectively).

CONCLUSION

Media at different pH values should be used for sensitivity tests according to the environment of C. albicans.

Chiral imine copper chloride-catalyzed enantioselective desymmetrization of 2-substituted 1,2,3-propanetriols

Catalytic enantioselective desymmetrization of meso-2-substituted glycerols has been developed to secure a novel synthetic route to chiral tertiary alcohols. The transformation has been realized by monobenzoylation using benzoyl chloride and triethylamine in the presence of the imine ligand (25)-CuCl2 complex in THF at ambient temperature. The desymmetrization turned out to be greatly dependent on acylating reagent, base, solvent, and needless to say, catalyst. Extensive screening of chiral ligands led us to combine bromopyridinecarboxaldehyde 1 and phenyloxazoline amine 12 derived from tert-leucine, the bromo and phenyl substituents of which proved to be indispensable. All of the substrates have been desymmetrized to the corresponding monobenzoates with high enantioselectivity up to 96% enantiomeric excess. The catalytic system allows broad structural diversity of substrates and its synthetic versatility has been demonstrated by an efficient synthetic route to a known key precursor 68 of triazole antifungals.

Recent developments in pradimicin-benanomicin and triazole antibiotics

Fungal infections are on the rise as the number of patients with compromised immune systems continues to increase. The need for safer and more effective antifungals has resulted in the search for novel drug classes and for modifications to existing classes, with the aim of enhancing their antifungal spectra and potency. In this review, two classes of antifungals are discussed: the pradimicin-benanomicin antibiotics and the newer triazole derivatives. These have activity against Candida spp., Cryptococcus neoformans and Aspergillus spp., as well as variable activity against other less commonly encountered fungi including Pneumocystis carinii. Pradimicins-benanomicins are generally fungicidal, whereas the newer azoles appear to be selectively fungicidal to Cryptococcus neoformans and Aspergillus spp. Pradimicin-benanomicin acts by binding to mannan and alters membrane integrity. One water-soluble pradimicin candidate, BMS-181184, has been selected for clinical development. The triazoles act by inhibiting cytochrome P450 sterol 14a-demethylase. Four triazoles either currently in clinical development (voriconazole and D0870) or being considered as clinical candidates (ER-30346 and Sch 56592) will be discussed. The antifungal spectra, pharmacokinetic and toxicologic data in animals, and efficacy results in experimental infection models will be reviewed for BMS-181184 and the four newer triazoles. Results from the early clinical trials for voriconazole and D0870 will also be discussed.

Fungicidal activity of fluconazole against Candida albicans in a synthetic vagina-simulative medium

Fluconazole (FLZ) has emerged as a highly successful agent in the management of systemic infections of Candida. Cure rates for symptomatic candidiasis following single 150-mg FLZ dose therapy exceed 90%. In vitro, however, FLZ is fungistatic only in a narrow pH range and is not effective at vaginal pH, 4.2. This study evaluated the effect of FLZ on Candida albicans under in vitro conditions resembling the vaginal microenvironment, using vagina-simulative medium (VS). We found that FLZ was fungicidal for C. albicans in VS, but not in other media at the same pH, 4.2. In VS, FLZ was fungicidal at concentrations of >/=8 micro g/ml and reduced viability by greater than 99.9%. Analysis of the components of VS indicated that 17 mM acetic acid, a concentration achieved in the vagina, was responsible for the synergistic, fungicidal effect. This effect was not seen at neutral pH. Other substrates were not effective substitutes for acetic acid; however, short-chained carboxylic acids, glyoxylate and malonate, were effective. Most strains of C. albicans that were resistant to FLZ under standard conditions were killed by FLZ plus acetate. Other species of Candida were also killed, except C. krusei and C. glabrata. This study shows that FLZ has fungicidal activity for Candida species under in vitro conditions that mimic the vaginal microenvironment. This raises the possibility that FLZ may also have fungicidal effects during treatment of vaginal candidiasis. Elucidating the mechanism by which FLZ and acetate interact may disclose vulnerable pathways that could be exploited in drug development.

The trailing end point phenotype in antifungal susceptibility testing is pH dependent

The interpretation of end points in azole antifungal drug susceptibility testing is problematic, in part due to incomplete growth inhibition of Candida species. Such trailing growth can cause the MICs of fluconazole for some isolates to be low (<1 microg/ml) after 24 h of growth but much higher (>64 microg/ml) after 48 h. Isolates having this type of growth have been described as having a low-high phenotype. Although these isolates would be considered resistant by current National Committee of Clinical Laboratory Standards definitions, growing evidence suggests that they are susceptible in vivo. To further characterize these isolates in vitro, microdilution susceptibility testing comparing the complex defined medium RPMI 1640 to a defined minimal medium (yeast nitrogen broth) was performed. Isolates having trailing growth in MOPS (morpholinepropanesulfonic acid)-buffered RPMI 1640 (pH 7.0) were found to have clear end points in the minimal medium at its native pH of 4.5. The pH of the medium influenced the low-high phenotype, as these same isolates trailed in minimal medium adjusted to a pH of >/=6.0 but did not trail in RPMI 1640 adjusted to a pH of </=5.0. This pH effect was independent of the medium buffering capacity, as trailing was decreased in both minimal medium and RPMI 1640 (pH 4.5) buffered in citrate. Adjustment in the pH of MOPS-buffered RPMI 1640 reduced trailing in multiple strains of Candida albicans without affecting the MICs for isolates having known susceptible (low-low) and resistant (high-high) phenotypes. Adjustment of the medium pH could be considered to eliminate trailing in azole drug susceptibility testing.

Colorimetric MTT assessment of antifungal activity of D0870 against fluconazole-resistant Candida albicans

The in vitro antifungal activity of D0870 against eight isolates of fluconazole-resistant Candida albicans was compared with that of itraconazole, ketoconazole and miconazole. The colorimetric MTT [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide] assay was used to assess the antifungal activities. The 50% minimum inhibitory concentration (MIC50) of D0870 was below 0.031 microgram ml-1 for seven isolates and 0.25 microgram ml-1 for one isolate. The activity of D0870 was superior to that of the other azoles. Ketoconazole was the most effective azole next to D0870. Therefore, the new bis-triazole, D0870, is expected to be promising for the therapy of fluconazole-resistant candidosis. The present data also confirmed that the MTT assay may be useful for evaluation of resistance and detection of resistant C. albicans.

Screening of new bioactive materials from microbial extracts of soil microorganism (I). Antimicrobial activity from 200 samples using microdilution assay

The microdilution assay recommended by NCCLS (National Committee for Clinical Laboratory Standards) is one of the standardized methods of antibiotic susceptibility test. This method has been widely used clinically to obtain MIC values of antibiotics on pathogenic microorganisms. It is more convenient, rapid and simple to test many samples than other test methods such as agar diffusion assay and broth macrodilution assay. The screening of antimicrobial agents from microbial extracts is too laborious in its process. Therefore, a number of screening methods having more simple procedure have been developed. In our laboratory, we applied microdilution assay for screening the antimicrobial agents. This assay showed dose-response results and was more sensitive than disc diffusion assay in our system. We tested 200 samples of microbial extracts originated from 100 microbial strains and selected several samples as potential candidates. In this report, we show that the microdilution assay is more convenient method in screening of antibiotic susceptibility than those previously reported.

Pharmacokinetics of two multiple-dosing regimens of D0870 in human immunodeficiency virus-positive patients: a phase I study

D0870 is a triazole with a broad antifungal spectrum, and it has been shown to have both in vitro and in vivo activities against wild-type and fluconazole-resistant strains of Candida albicans. Twenty-two human immunodeficiency virus (HIV)-positive male subjects were enrolled in an open, nonrandomized trial investigating the pharmacokinetics of two different dosing regimens of D0870 and assessing the safety of multiple oral doses of D0870 in HIV-positive subjects and their ability to tolerate multiple oral doses. Nine subjects received an initial loading dose of 50 mg, followed by four once-daily maintenance doses of 10 mg. A further nine subjects received an initial 200-mg loading dose followed by four daily maintenance doses of 25 mg. All subjects were fasting. A single loading dose of 50 mg of D0870 resulted in a mean maximum concentration in serum (Cmax) of 107 +/- 32 ng/ml. Concentrations in plasma were maintained by the 10-mg once-daily dosing regimen as seen by the similar values of the area under the concentration-time curve from 0 to 24 h following dosing on days 1 and 5 and a mean accumulation ratio close to unity (0.90). The terminal plasma half-life of D0870 in plasma following dosing on day 5 ranged from 23 to 85 h (mean, 49 h). A single loading dose of 200 mg of D0870 resulted in a Cmax of 431 +/- 186 ng/ml. Concentrations in plasma were again maintained by the 25-mg daily dosing regimen, with the mean accumulation ratio being close to unity (1.17). The terminal half-life of D0870 in plasma following dosing on day 5 of phase II of the study ranged from 34 to 137 h (mean, 71 h). In addition, the concentrations achieved in the plasma of these HIV-positive subjects were similar to the values predicted from simulations based on data derived from normal, healthy subjects. D0870 was well tolerated. No serious adverse events were experienced during the course of the study, and all volunteers completed the trial. A total of 15 adverse events were reported, but none were considered to be related to the administration of D0870 and all had resolved by the end of the trial. No changes in the hematology, clinical chemistry, or urinalysis parameters were considered to be related to dosing with D0870. No clinically significant changes in the electrocardiogram parameters were noted during the trial. The data generated in this trial support further investigation of these regimens with HIV-positive subjects with fluconazole-susceptible or -resistant oropharyngeal candidosis.

Comparison of the in vitro activities of the echinocandin LY303366, the pneumocandin MK-0991, and fluconazole against Candida species and Cryptococcus neoformans

Two new glucan synthesis inhibitors, the echinocandin LY303366 and the pneumocandin MK-0991 (formerly L-743,872), were studied for their antifungal activities in vitro in relation to each other and in relation to the activity of the triazole fluconazole. Systematic analysis of broth macrodilution testing by varying the starting inoculum size, medium composition, medium pH, temperature of incubation, length of incubation, or selection of endpoints failed to identify significant differences in antifungal activity for either LY303366 or MK-0991 in comparison to the activity under standard test conditions specified for other antifungal agents in National Committee for Clinical Laboratory Standards (NCCLS) document M27A. Under standardized conditions, both drugs exhibited prominent activity against Candida species including Candida glabrata and Candida krusei but showed little activity against Cryptococcus neoformans. This spectrum of activity differed from that of fluconazole, which exhibited marginal activity against C. glabrata and C. krusei but prominent activity against other Candida species and C. neoformans. For individual strains, broth microdilution MICs of LY303366 and MK-0991 were similar to but frequently higher than broth macrodilution results. In contrast, fluconazole broth microdilution MICs were often lower than broth microdilution results. We conclude that the test conditions specified in NCCLS document M27A are applicable to these two new glucan synthesis inhibitors and that systematic differences between broth microdilution procedures and the broth macrodilution reference standard will need to be addressed before the two test methods can be used interchangeably.

A dose comparison study of a new triazole antifungal (D0870) in HIV-positive patients with oral candidiasis

OBJECTIVE

This multicentre study evaluated the clinical efficacy and tolerability of D0870 in treating oropharyngeal candidiasis in HIV-positive patients who had no history of clinical resistance to fluconazole.

METHODS

Three regimens were evaluated in two phases. In phase I a 50 mg initial dose was followed by 10 mg for 4 days (Group 1). In phase II a 100 mg initial dose was followed by 25 mg for 4 days (Group 2), or 10 mg for 5 days (Group 3).

RESULTS

Clinical cure was obtained in 27 patients of a total of 35 (77%) and six other patients improved (17%). Two patients at the lowest dose failed and both had very low plasma concentration of D0870. No association was found between clinical outcome; minimum inhibitory concentration of D0870 pre-therapy for Candida albicans, maximum recorded plasma D0870 concentration, cfu of culture or CD4 cell count at entry. Overall, 37% of the patients experienced relapse during the 2 weeks post therapy. Tolerance was excellent. Mild adverse events possibly related to the study drug were recorded in five patients.

CONCLUSION

D0870 demonstrates excellent efficacy at low doses in the treatment of HIV-related OPC and exhibits a favourable safety profile.

Therapy of systemic histoplasmosis in immunosuppressed mice with the triazole D0870

Because histoplasmosis is a life-threatening disease in AIDS and other compromised patients, we examined the efficacy of D0870 (Zeneca) in immunosuppressed mice against systemic histoplasmosis. Oral therapy with fluconazole given once daily (QD) was ineffective in prolonging survival, whereas itraconazole given once or twice daily (BID), fluconazole given BID or D0870 given QD or given every other day (QOD) were efficacious (P < 0.001). Burdens of Histoplasma capsulatum in the liver and spleen of survivors showed that D0870 given QD or QOD and itraconazole given BID caused dose-responsive reduction of infectious burden. Infection was cleared more readily from the liver than from the spleen. Overall, D0870 was > or = 20-fold more efficacious than fluconazole or itraconazole and itraconazole was > ten-fold better than fluconazole for the treatment of systemic histoplasmosis in the immunosuppressed model.

Comparison of D0870, a new triazole antifungal agent, to fluconazole for inhibition of Candida albicans cytochrome P-450 by using in vitro assays

D0870 was 12 to 15 times more active than fluconazole in experiments to determine the MIC for growth arrest for two isolates of Candida albicans. A biochemical comparison of in vitro sterol biosynthesis in cell extracts showed only a twofold superiority of D0870 over fluconazole. A large differentiation (10-fold) in 50% saturating concentrations obtained by examining the binding of the azoles to microsomal P-450 was observed in a type II binding spectrophotometric assay, possibly reflecting the differential affinity for more than one P-450 enzyme. Additional mechanisms besides affinity for the target enzyme sterol 14 alpha-demethylase, such as differential intracellular accumulation of drug, may contribute to the differences in antifungal activity.

Efficacy of D0870 compared with those of itraconazole and amphotericin B in two murine models of invasive aspergillosis

D0870 is a novel azole antifungal compound. It was compared with conventional amphotericin B and itraconazole therapy in two murine models of invasive aspergillosis, one a systemic nonimmunocompromised mouse model and the other a temporarily neutropenic mouse respiratory model. D0870 was given orally and achieved measurable concentrations in serum approximately proportional to the daily dose with accumulation over time if it was given twice daily. Amphotericin B at 3.3 mg/kg of body weight was given intraperitoneally for four to six doses, and itraconazole was given orally in a cyclodextrin suspension at 5 to 50 mg/kg daily or twice daily (BID). The duration of therapy varied from 7 to 14 days. In the nonimmunocompromised mouse model, D0870 at 25 mg/kg BID was slightly inferior to amphotericin B and itraconazole with regard to mortality, with a median survival of 20 days for the three groups (P = 0.03 compared with amphotericin B). However, D0870 at 25 mg/kg BID was inferior to amphotericin B (but not itraconazole) with respect to renal culture (P = 0.01) and brain culture (P = 0.0001) results. Only amphotericin B was statistically superior to controls with regard to mortality. In the neutropenic mouse respiratory model, D0870 at 50 mg/kg/day was superior to amphotericin B, itraconazole, and controls with regard to mortality. D0870 at both 25 and 50 mg/kg/day was statistically superior to controls with regard to lung culture results (P = 0.004 to 0.04). A second experiment with a higher inoculum showed that no drug regimen was effective in that model. In all models low doses and concentrations of D0870 in serum were ineffective. D0870 has some efficacy for the treatment of invasive aspergillosis when it is given at modest doses.

In vitro activity of D0870 compared with those of other azoles against fluconazole-resistant Candida spp

We compared the in vitro activity of a new triazole, D0870, with those of fluconazole, itraconazole, and ketoconazole against 41 clinical isolates of fluconazole-resistant Candida belonging to nine different species. The 50% inhibitory concentrations (IC50s) were determined by a microdilution method with morpholinopropanesulfonic acid (MOPS)-buffered RPMI medium and an inoculum of approximately 10(4) yeasts per ml. After incubation for 48 h at 37 degrees C the optical density at 550 nm was measured. The IC50 was the lowest drug concentration which reduced the optical density at 550 nm by > or = 50% compared with that for a drug-free control. D0870 had significant activity against many of the isolates. Its activity was comparable to that of ketoconazole, slightly superior to that of itraconazole, and markedly superior to that of fluconazole against Candida albicans. Against Candida glabrata, Candida krusei, and Candida inconspicua, it had activity similar to those of itraconazole and ketoconazole but had activity superior to that of fluconazole. D0870 IC50s for some isolates were increased. This may be due to cross-resistance mechanisms because the IC50s of both itraconazole and ketoconazole for these isolates were often high. When IC50s and IC80s were compared there was a marked organism and drug variation. With C. glabrata much higher endpoints for itraconazole were observed when an IC80 endpoint was used. For C. albicans there was also a significant shift upward in endpoints for itraconazole and ketoconazole. Values were changed little when IC50 and IC80 endpoints of D0870 were compared. For 35 of 41 isolates tested the D0870 IC50 was less than the 2.5-mg/liter breakpoint threshold proposed previously. Therefore, D0870 may be a useful agent for the therapy of infections caused by fluconazole-resistant Candida spp.

Efficacy of the triazole D0870 in a murine model of systemic histoplasmosis

The efficacy of D0870 was studied in a murine model of systemic histoplasmosis and was compared with that of fluconazole. All regimens of D0870 (1 or 10 mg/kg of body weight given daily or 1, 10, or 100 mg/kg given every other day) and 100 mg of fluconazole per kg given daily provided complete protection from lethality. Comparison of the number of viable Histoplasma capsulatum yeasts remaining in the spleen or liver indicated that D0870 was superior to fluconazole in clearing and curing infection. D0870 was 10- to 100-fold more efficacious than fluconazole in the treatment of experimental histoplasmosis.

Activities of D0870, a novel triazole, against Candida lusitaniae and Trichosporon beigelii in experimental murine infections

Candida lusitaniae and Trichosporon beigelii may cause life-threatening infections in the immunocompromised host and may be resistant to amphotericin B. We assessed the activities of a new triazole, D0870, against one T. beigelii and four C. lusitaniae strains, in comparison with those of fluconazole and amphotericin B. Immunosuppressed CF1 mice, intravenously infected with each fungal strain, received 3 days of therapy with oral D0870 (5 or 25 mg/kg of body weight daily), fluconazole (5 to 50 mg/kg daily), or parenteral amphotericin B (1 or 2 mg/kg daily). Survival was significantly prolonged and kidney fungus titers were reduced in mice treated with D0870 compared with untreated mice (P < or = 0.05). Treatment with D0870 was significantly more effective than that with amphotericin B or fluconazole in animals infected with two of the C. lusitaniae strains and equally effective for the remaining two C. lusitaniae strains and the T. beigelii strain. Fluconazole and amphotericin B failed to improve the survival of mice infected with one and two C. lusitaniae strains, respectively. D0870 was active against all the organisms tested, including those resistant to fluconazole and amphotericin B.

In vitro activity of a new antifungal triazole, D0870, against Candida albicans isolates from oral cavities of patients infected with human immunodeficiency virus

We investigated the in vitro activity of a new antifungal triazole, D0870, against 100 Candida albicans isolates from the oral cavities of patients infected with human immunodeficiency virus by using a broth macrodilution method following the recommendations provided by the National Committee for Clinical Laboratory Standards (document M27-P). All of the isolates were chosen from C. albicans isolates already tested for fluconazole susceptibility by the procedure of the National Committee for Clinical Laboratory Standards. Fifty isolates were considered fluconazole susceptible (MICs, < or = 4 micrograms/ml), and 50 isolates were considered fluconazole resistant (MICs, > or = 8 micrograms/ml). The in vitro data demonstrated that D0870 had good activity against isolates tested; for 90% of all strains of C. albicans, MICs were 0.5 micrograms/ml. However, the D0870 MICs for the fluconazole-susceptible isolates were lower than those for the fluconazole-resistant isolates; MICs for 50 and 90% of the isolates tested were < or = 0.0078 and 0.06 micrograms/ml, respectively, for fluconazole-susceptible isolates and 0.25 and 2 micrograms/ml, respectively, for fluconazole-resistant isolates (P < 0.001). Our data suggest that this new triazole could represent a valid alternative in the treatment of oral candidiasis in human immunodeficiency virus-infected patients.

Comparative study of broth macrodilution and microdilution techniques for in vitro antifungal susceptibility testing of yeasts by using the National Committee for Clinical Laboratory Standards' proposed standard

A comparative study of broth macro- and microdilution methods for susceptibility testing of fluconazole, itraconazole, flucytosine, and amphotericin B was conducted with 273 yeasts. The clinical isolates included 100 Candida albicans, 28 Candida tropicalis, 25 Candida parapsilosis, 15 Candida lusitaniae, 15 Candida krusei, 50 Cryptococcus neoformans var. neoformans, 25 Torulopsis (Candida) glabrata, and 15 Trichosporon beigelii strains. Both methods were performed according to the National Committee for Clinical Laboratory Standards' (NCCLS) recommendations (document M27-P). For fluconazole, itraconazole, and flucytosine, the endpoint was the tube that showed 80% growth inhibition compared with the growth control for the macrodilution method and the well with slightly hazy turbidity (score 1) compared with the growth control for the microdilution method. For amphotericin B, the endpoint was the tube and/or well in which there was absence of growth. For the reference macrodilution method, the MICs were determined after 48 h of incubation for Candida spp., T. glabrata, and T. beigelii and after 72 h for C. neoformans var. neoformans. For the microdilution method, either the first-day MICs (24 h for all isolates other than C. neoformans and 48 h for C. neoformans var. neoformans) or the second-day MICs (48 and 72 h, respectively) were evaluated. The agreement within one doubling dilution of the macrodilution reference for all drugs was higher with the second-day MICs than with the first-day MICs for the microdilution test for most of the tested strains. General agreement was 92% for fluconazole, 85.7% for itraconazole, 98.3% for flucytosine, and 96.4% for amphotericin B. For C. neoformans var. neoformans and T. beigelii, the agreement of the first-day reading was higher than that of the second-day reading for fluconazole (94 versus 92%, respectively, for C. neoformans var. neoformans, and 86.7 versus 80%, respectively, for T. beigelii). Our studies indicate that the microdilution technique performed following the NCCLS guidelines with a second-day reading is a valid alternative method for testing fluconazole, itraconazole, flucytosine, and amphotericin B against these eight species of yeasts.

Treatment of disseminated Torulopsis glabrata infection with DO870 and amphotericin B

Torulopsis glabrata, an opportunist pathogen in immunosuppressed patients, is resistant to many antifungal agents, and there are no established treatment regimens for this organism. The mouse model was used to evaluate treatment with DO870, amphotericin B, fluconazole, and their combination. Mice were immunosuppressed with 5 mg of gold sodium thiomalate given intraperitoneally 1 day prior to intravenous infection with 10(8) T. glabrata cells. Treatment with a new antifungal triazole, DO870, at doses ranging from 1 to 50 mg/kg of body weight administered per os either daily or on alternate days; fluconazole at 100 mg/kg twice a day per os; or amphotericin B at 3 mg/kg/day intraperitoneally was begun 1 day after infection. Treatment for 5 days was followed by sacrifice 2 days later for determining CFU counts in spleen and kidney tissue. For a fluconazole-sensitive isolate (MIC of DO870, < 1.25 micrograms/ml), DO870 at 5 mg/kg/day significantly reduced counts in kidney and spleen tissue (P < 0.05), amphotericin B was modestly effective, and the combination of DO870 (25 mg/kg) and amphotericin B (3 mg/kg) was markedly more effective than either drug alone (P < 0.01). Three additional isolates were resistant in vitro to DO870 (MIC, 4 micrograms/ml). No reduction in CFU in kidney or spleen tissue was observed with DO870 when compared with counts in control tissue. DO870 is effective in vivo against at least some isolates of T. glabrata and when combined with amphotericin B can exert additive effects.

Antifungal activity of a new triazole, D0870, compared with four other antifungal agents tested against clinical isolates of Candida and Torulopsis glabrata

D0870 is a new triazole agent with potent, broad-spectrum antifungal activity. We investigated the in vitro activity of D0870, fluconazole, itraconazole, amphotericin B, and 5-fluorocytosine (5FC) against 319 clinical isolates of Candida spp. and Torulopsis glabrata. In vitro susceptibility testing was performed using a microdilution broth method performed according to NCCLS guidelines. D0870 was very active (MIC90 of 0.12 microgram/ml and 0.5 microgram/ml at 24 and 48 h incubation, respectively) against all of the yeast isolates. D0870 was 2- to 32-fold more active than amphotericin B and 2- to 8500-fold more active than 5FC. By comparison with the other triazoles, D0870 was generally 2- to 16-fold more active than itraconazole and > or = 16-fold more active than fluconazole. More than half (53%) of C. albicans isolates with elevated fluconazole and itraconazole MICs (> or = 128 micrograms/ml and > 8.0 micrograms/ml, respectively) were inhibited by < or = 1.0 microgram/ml of D0870. Based on these studies, D0870 has promising antifungal activity and warrants further in vitro and in vivo investigation.