Comparison of amphotericin B and N-D-ornithyl amphotericin B methyl ester in experimental cryptococcal meningitis and Candida albicans endocarditis with pyelonephritis.

Amphotericin B and N-D-ornithyl amphotericin B methyl ester were compared for therapeutic efficacies against experimentally induced cryptococcal meningitis and Candida albicans endocarditis with pyelonephritis in rabbits. Antifungal activity of the two polyenes in vitro was similar for the yeasts used in these experiments. N-D-ornithyl amphotericin B methyl ester gave a slightly higher concentration in serum than amphotericin B did, but both drugs had similar elimination curves, and penetration into the cerebrospinal fluid was poor for both. Despite these similarities between the two polyenes, amphotericin B was much more effective than N-D-ornithyl amphotericin B methyl ester in the treatment of cryptococcal meningitis in rabbits. For C. albicans endocarditis, both polyenes had similar cure rates, but in vitro measurement of fungicidal activity in serum did not predict treatment outcome. For C. albicans pyelonephritis, both polyenes showed efficacy; because higher doses of the less toxic methyl ester could be used, it sterilized the urinary tract more often than amphotericin B. These studies indicate that in vivo and in vitro experiments may be needed to predict the results of treatment with polyenes.     

5-fluorocytosine and amphotericin B in bronchial secretions

The penetration into and clearance from bronchial secretions of 5-fluorocytosine and amphotericin B were studied in a dog model. After a single intravenous dose of 35 mg/kg, 5-fluorocytosine intrabronchial concentrations were greater than the minimal inhibitory concentration for 80 to 90% of Candida species. These inhibitory concentrations persisted up to 3 h. In contrast, amphotericin B in intravenous doses of 0.6 and 1.2 mg/kg penetrated the blood-bronchus barrier poorly.     

In vitro-clinical correlations for amphotericin B susceptibility in AIDS-associated cryptococcal meningitis

Reliable measures of antifungal drug susceptibility are needed. We tested the susceptibility of Cryptococcus neoformans from patients treated with amphotericin B. In vitro susceptibility employed a modified broth macrodilution method. We demonstrate a strong correlation between the quantitative measures of in vitro amphotericin B susceptibility and the quantitative response observed in patients.     

两性霉素B联合氟胞嘧啶治疗新型隐球菌脑膜炎1例的护理

隐球菌脑膜炎是由新型隐球菌所致的中枢神经系统感染性疾病。近年来,隐球菌脑膜炎的发病率有上升趋势。据报道,隐球菌侵犯中枢神经系统占隐球菌感染的80％,此病常进行性加重,预后不良,死亡率较高。因此,早期、快速诊断、及时治疗是降低隐球菌脑膜炎病死率的关键。我科2011年9月收治新型隐球菌脑膜炎1例,现将护理体会报告如下。     

Interactions among amphotericin B, 5-fluorocytosine, ketoconazole, and miconazole against pathogenic fungi in vitro.

Interactions among amphotericin B, 5-fluorocytosine, ketoconazole, and micoconazole were tested for all possible paired and triple drug combinations and all four drugs combined against three isolates of Candida albicans, three Candida spp., two isolates of Cryptococcus neoformans, and three isolates Aspergillus fumigatus. An assay for inhibitory activity was developed in which growth in the presence of an antifungal agent was expressed as a percentage of the growth in drug-free cultures. For nearly all of the antifungal combinations, the interaction was additive against most fungal isolates. Drug combinations that included amphotericin B and ketoconazole were most often synergistic, i.e., amphotericin plus ketoconazole, amphotericin plus 5-fluorocytosine plus ketoconazole, and amphotericin plus 5-fluorocytosine plus ketoconazole plus miconazole, whereas the combination of ketoconazole plus miconazole showed the strongest tendency towards antagonism. The data in this screening survey provide a basis for further studies of drug interactions in vivo and in vitro.     

Efficacies of high-dose fluconazole plus amphotericin B and high-dose fluconazole plus 5-fluorocytosine versus amphotericin B, fluconazole, and 5-fluorocytosine monotherapies in treatment of experimental endocarditis, endophthalmitis, and pyelonephritis due to Candida albicans

We compared the efficacies of fluconazole (Flu), amphotericin B (AmB), and 5-fluorocytosine (5FC) monotherapies with the combination of Flu plus 5FC and Flu plus AmB in a rabbit model of Candida albicans endocarditis, endophthalmitis, and pyelonephritis. The dose of Flu used was that which resulted in an area under the concentration-time curve in rabbits equivalent to that seen in humans who receive Flu at 1,600 mg/day, the highest dose not associated with central nervous system toxicity in humans. Quantitative cultures of heart valve vegetations, the choroid-retina, vitreous humor, and kidney were conducted after 1, 5, 14, and 21 days of therapy. All untreated controls died within 6 days of infection; animals treated with 5FC monotherapy all died within 18 days. In contrast, 93% of animals in the other treatment groups appeared well and survived until they were sacrificed. At day 5, the relative decreases in CFU per gram in the vitreous humor were greater in groups that received Flu alone and in combination with 5FC or AmB than in groups receiving AmB or 5FC monotherapies (P < 0. 005) but were similar thereafter. In the choroid-retina, 5FC was the least-active drug. However, there were no differences in choroidal fungal densities between the other treatment groups. On days 5 and 14 of therapy, fungal densities in kidneys of AmB recipients were lower than those resulting from the other therapies (P < 0.001 and P < or = 0.038, respectively) and AmB-plus-Flu therapy was antagonistic; however, all therapies for fungal pyelonephritis were similar by treatment day 21. While fungal counts in cardiac valves of Flu recipients were similar to those of controls on day 5 of therapy and did not change from days 1 to 21, AmB therapy significantly decreased valvular CFUs versus Flu at days 5, 14, and 21 (P < 0.005 at each time point). 5FC plus Flu demonstrated enhanced killing in cardiac vegetations compared with Flu or 5FC as monotherapies (P < 0. 03). Similarly, the combination of AmB and Flu was more active than Flu in reducing the fungal density in cardiac vegetations (P < 0.03). However, as in the kidney, AmB plus Flu demonstrated antagonism versus AmB monotherapy in the treatment of C. albicans endocarditis (P < 0.05, P = 0.036, and P < 0.008 on days 5, 14, and 21, respectively).     

Successful treatment of cryptococcal meningitis with amphotericin B colloidal dispersion: report of four cases.

Four patients with cryptococcal meningitis were treated with amphotericin B colloidal dispersion because of nephrotoxicity from prior treatment with conventional amphotericin B. The limited experience presented here suggests that amphotericin B colloidal dispersion is efficacious for the treatment of cryptococcal meningitis, despite being undetectable in cerebrospinal fluid, and offers a potential therapeutic alternative for patients who cannot tolerate conventional amphotericin B.     

Antagonistic effects of fluconazole and 5-fluorocytosine on candidacidal action of amphotericin B in human serum.

This study addressed the effects of fluconazole and 5-fluorocytosine on the candidacidal activity of amphotericin B in the presence of human serum. A Candida albicans isolate that was susceptible to all three agents according to standard testing procedures was employed. Fungicidal activity was estimated by using a flow cytometric procedure that exploited the fact that yeast cells killed by amphotericin B diminish in size and take up propidium iodide. The following findings were made. (i) Fluconazole and 5-fluorocytosine each failed to inhibit pseudohyphal formation and cell aggregation even when applied at 10 and 50 micrograms/ml, respectively, for up to 10 h. Hence, these agents were not fungistatic when tested in the presence of serum. (ii) Simultaneous application of 5-fluorocytosine had neither enhancing nor inhibitory effects on the fungicidal activity of amphotericin B. However, yeasts that were preincubated for 20 h with 5-fluorocytosine became less susceptible to killing by amphotericin B. (iii) Fluconazole exerted a frank antagonistic effect on the fungicidal activity of amphotericin B. Thus, under our in vitro conditions, both fluconazole and 5-fluorocytosine can overtly antagonize the candidacidal action of amphotericin B.     

In vitro susceptibility of 245 yeast isolates to amphotericin B, 5-fluorocytosine, ketoconazole, fluconazole and itraconazole.

The in vitro activity of amphotericin B, 5-fluorocytosine, ketoconazole, fluconazole and itraconazole was tested against 245 yeast strains isolated from clinical specimens (68 Candida albicans, 74 Candida tropicalis, 43 Candida krusei, 28 Candida glabrata, 19 Candida parapsilosis, 8 Candida lusitaniae and 5 Candida guilliermondii). An agar dilution method was employed to carry out testing. Minimal inhibitory concentrations to restrain 90% of isolate growth (MIC90) ranged from 0.12 to 2 mg/l for amphotericin B and for 5-fluorocytosine, from 0.03 to 8 mg/l for ketoconazole, from 0.05 to 50 mg/l for itraconazole and from 0.1 to > 100 mg/l for fluconazole. Among the azole derivatives, the most active was ketoconazole, followed by itraconazole. Only 1 strain of C. albicans was resistant to amphotericin B (MIC > 4 mg/l). Both C. tropicalis and C. krusei responded poorly to fluconazole and the former to itraconazole as well. The species most susceptible to the antifungal agents tested was C. glabrata and the most resistant were C. tropicalis and C. krusei.     

Susceptibilities of serial Cryptococcus neoformans isolates from patients with recurrent cryptococcal meningitis to amphotericin B and fluconazole.

Amphotericin B and fluconazole susceptibilities of 13 Cryptococcus neoformans isolates from five patients with recurrent cryptococcal meningitis were determined. For each patient, serial isolates showed no increase in antibiotic resistance relative to the initial isolate. For these patients, recurrent disease was not due to drug resistance but may reflect changes in immune function and/or poor compliance.     

In vitro susceptibility of 119 yeast isolates to fluconazole, 5-fluorocytosine, amphotericin B and ketoconazole

The in vitro activity of fluconazole was tested against 13 yeast species (119 strains) isolated from clinical specimens during a 3-month period. For comparative purposes, three other antifungal compounds (5-fluorocytosine, amphotericin B and ketoconazole) were also tested. The tests were carried out using a microautomated method previously developed in our laboratory. The method allowed us to determine the minimum inhibitory concentration (MIC) of the four antifungal drugs used. For each of the drugs we utilized different media. The MIC ranges (mg/l) of fluconazole were: 0.04-12.5 for Candida albicans, 0.19-6.25 for Candida parapsilosis, 12.5-50 for Candida krusei, 0.04-100 for Candida tropicalis, 0.04- greater than 100 for Candida glabrata, 0.09- greater than 25 for Cryptococcus neoformans, 0.09-0.78 for Saccharomyces cerevisiae, 6.25- greater than 100 for Trichosporon beigelii and 0.09-0.19 for Blastoschizomyces capitatus (Trichosporon capitatum). The MIC value (mg/l) was 0.39 for Candida guilliermondii and Candida lusitaniae, greater than 100 for Cryptococcus laurentii and 0.09 for the 3 isolates of Torulopsis candida. These results were obtained using the medium recommended for in vitro testing of fluconazole (high-resolution medium) by Pfizer UK.     

Synergism between the antifungal agents amphotericin B and alkyl glycerol ethers.

The alkyl glycerol ether rac-1-O-dodecylglycerol inhibited the growth of members of two genera of yeasts, Candida and Cryptococcus, and was strongly synergistic with amphotericin B. At one-half its MIC, dodecylglycerol decreased the MIC of amphotericin B by as much as 80-fold. This high degree of synergism between dodecylglycerol and amphotericin B was demonstrated against a number of species of yeasts including Candida albicans, Candida tropicalis, Candida parapsilosis, Cryptococcus neoformans, Cryptococcus albidus, and Cryptococcus laurentii. All fractional inhibitory concentrations (for all strains and species) were calculated to be less than 1, and most were less than 0.6, again demonstrating strong synergism. Other alkyl glycerol ethers with alkyl chain lengths ranging from 8 to 18 carbon atoms were also found to be synergistic with amphotericin B against C. neoformans and C. albicans. Electron microscopy experiments showed that C. neoformans grown in the presence of dodecylglycerol had severely abnormal, deformed capsules. Although the mechanism of action of dodecylglycerol is not known, dodecylglycerol was not simply acting as a detergent. The natural detergent sodium deoxycholate could not substitute for dodecylglycerol. At comparable and higher concentrations, sodium deoxycholate had no fungicidal effect on its own, nor did it potentiate the activity of amphotericin B. Dodecylglycerol did not interact synergistically with the water-soluble antifungal agent fluconazole. The lipid-soluble hydrophobic properties of amphotericin B appear to be important for this synergistic effect, in that alkyl glycerol ethers could promote synergism with amphotericin B by potentially increasing the interaction between membrane-bound ergosterol and amphotericin B.     

5-fluorocytosine susceptibility of pathogenic fungi in the presence of allopurinol: potential for improving the therapeutic index of 5-fluorocytosine.

The minimal inhibitory concentration of 5-fluorocytosine in 18 pathogenic fungal isolates was not altered by either allopurinol (100 microM) or oxypurinol (100 microM). Since allopurinol at this level clinically has been demonstrated to interfere with 5-fluorouracil anabolism, thereby reducing toxicity owing to 5-fluorouracil, allopurinol may be useful in counteracting the 5-fluorouracil-induced myelotoxicity observed in patients being treated with 5-fluorocytosine without interfering with the antifungal activity of 5-fluorocytosine.     

Amphotericin B and fluconazole, a potent combination therapy for cryptococcal meningitis

We evaluated the antifungal activities of amphotericin B, fluconazole, and flucytosine, alone and in combination, in a murine model of cryptococcal meningitis. The objectives were to determine the greatest antifungal effects achievable with these drugs alone or in combination. Meningitis was established in male BALB/c mice weighing 23 to 25 g by intracerebral injection of Cryptococcus neoformans. Treatment was started on day 2. Amphotericin B was tested at 0.3 to 1.3 mg/kg of body weight/day by slow intravenous injection. Fluconazole at 10 to 40 mg/kg/day and flucytosine at 20 to 105 mg/kg/day were administered in the sole source of drinking water. The mice were killed at 16 days, and the numbers of fungal colonies in the brain were quantified. The association between the response and the dose combination was evaluated by local nonparametric response surface methods; 99% confidence intervals were used to evaluate the antifungal effects. Ninety-five percent of the mice treated with amphotericin B at 0.5 mg/kg survived to the end of the experiment, regardless of the fluconazole or flucytosine dose used. The greatest activity was seen with amphotericin B plus fluconazole with or without flucytosine. However, the addition of flucytosine did not increase the antifungal activity. Given the widespread availability of amphotericin B and fluconazole and the relative safety profile of fluconazole compared to that of flucytosine, the full potential of this two-drug combination deserves further evaluation.     

A comparison of the efficacy of itraconazole, amphotericin B and 5-fluorocytosine in the treatment of Aspergillus fumigatus endocarditis in the rabbit

The efficacy of amphotericin B, 5-fluorocytosine and itraconazole was compared for the treatment of experimental rabbit Aspergillus fumigatus endocarditis. Therapy with amphotericin B or 5-fluorocytosine, at dosages of 3.0 and 35 mg/kg body weight respectively, failed to eradicate aspergillus from the cardiac vegetations in all but one of the animals tested; none of these animals survived for longer than nine treatment days. When similar doses of amphotericin and 5-fluorocytosine were administered concomittantly, 30% of the animals had sterile vegetations. Itraconazole at 2.5 and 3.5 mg/kg body weight was not successful; all the animals tested had infected vegetations and did not survive beyond nine days of therapy. In contrast, itraconazole at 5.0 mg/kg sterilised the endocardial vegetations and all these animals survived for 14 days. It is concluded that itraconazole may be useful in the treatment of aspergillus endocarditis.     

Comparison of itraconazole and fluconazole in treatment of cryptococcal meningitis and candida pyelonephritis in rabbits.

Itraconazole and fluconazole, two new triazoles, were examined for their antifungal activity in rabbits. Fluconazole easily crossed the blood-cerebrospinal fluid barrier, and active drug was eliminated in high concentrations in the urine. On the other hand, itraconazole did not cross the blood-cerebrospinal fluid barrier in measurable amounts, and urine concentrations were variable. Despite differences in pharmacokinetics at the site of infection, both agents were equally effective in treating cryptococcal meningitis and candida pyelonephritis in animals. By using a ketoconazole-resistant strain of Candida albicans, we showed that there was cross-resistance in vivo between these two new triazole compounds.     

Comparative in vitro and in vivo evaluation of N-D-ornithyl amphotericin B methyl ester, amphotericin B methyl ester, and amphotericin B.

N-D-Ornithyl amphotericin B methyl ester (O-AME), a semisynthetic derivative of amphotericin B methyl ester (AME), was compared with amphotericin B (AMB) and AME. In vitro, O-AME was more active than the other two against Candida spp. and other fungi and was only slightly affected by inoculum size, addition of serum, or changes in pH. In vivo, the dose of O-AME required to produce a 10,000-fold reduction of Candida albicans in a mouse kidney infection was similar to that of AMB and 1/10 that of AME. After intravenous treatment of infected mice and rats and subcutaneous treatment of mice, average 50% protective doses for O-AME and AMB were similar. Acute intravenous 50% lethal doses in mice indicated that O-AME was one-ninth as toxic as AMB but twice as toxic as AME. Acute renal function tests in rats indicated that Sch 28191 was less than 1/10 as toxic as AMB and slightly more toxic than AME. On this basis, the calculated advantage relative to AMB (with AMB equal to 1) was 8 for O-AME and 1.5 for AME.     

Comparison of cilofungin and amphotericin B for therapy of murine candidiasis.

We compared the efficacies of cilofungin and amphotericin B treatment in a murine model of disseminated candidiasis. Three different dosages of each drug plus controls were evaluated. Statistically improved survival was noted only among mice treated with 1 mg of amphotericin B per kg of body weight (P less than 0.05). While all amphotericin B regimens and the two lower-dosage cilofungin regimens significantly reduced yeast cell counts in kidneys compared with the controls, the amphotericin B-treated mice had a significantly higher percentage of sterile kidneys following therapy compared with those treated with cilofungin (P = 0.0001).