Treatment of systemic fungal infections: recent progress and current problems

Comparison of fluconazole and amphotericin B in prophylaxis of experimental Candida endocarditis caused by non-C. albicans strains

Amphotericin B (1 mg/kg of body weight, intravenous) and fluconazole (100 mg/kg, intraperitoneal) were compared in the prophylaxis of experimental Candida endocarditis caused by drug-susceptible, non-C. albicans strains C. tropicalis and C. parapsilosis. Neither antifungal agent was effective at preventing endocarditis due to either Candida strain when either agent was administered in a single-dose regimen (1 h prior to fungal challenge); the prophylactic efficacy of both agents increased substantially when a second prophylactic dose was given (24 h postchallenge). The excellent prophylactic efficacy of fluconazole, a fungistatic agent, underscores the importance of microbistatic mechanisms in endocarditis prophylaxis.

Factors associated with the development of candidemia and candidemia-related death among liver transplant recipients

OBJECTIVE

The authors' objective was to identify factors associated with candidemia and candidemia-related death among adult liver transplant recipients.

SUMMARY BACKGROUND DATA

Invasive candidiasis is the most common severe fungal infection occurring after liver transplantation and is associated with high morbidity and mortality rates. Although candidemia is not always found during invasive candidiasis, it has been considered as an indicator of invasive candidiasis in immunocompromised patients.

METHODS

A time-matched case-control study of 26 patients with candidemia, which was defined as the isolation of Candida from at least one blood culture, and 52 control patients without candidemia was reported. Two control patients were matched with each case patient regarding time of transplantation and duration of follow-up.

RESULTS

Between December 1985 and December 1992, candidemia developed in 1.4% of adult liver transplant recipients a median of 25 days after transplantation (range, 2-1690 days). The overall mortality rate among patients with candidemia was 81%, and 71% of these deaths were related to candidemia. Conditional logistic regression analysis was used to identify factors associated with candidemia, which were 1) hyperglycemia treated with insulin up to 2 weeks before candidemia (odds ratio [OR], 16.15; p = 0.002), and 2) exposure to more than three different intravenous antibiotics before development of candidemia (OR, 11.15; p = 0.005). The variables predictive of death related to candidemia were abdominal surgery performed up to 1 week before candidemia (relative risk [RR], 7.25; p = 0.02), high white blood cell count (RR, 1.10; p = 0.01), lower platelet count (RR, 0.99; p = 0.02), and elevated AST with candidemia (RR, 1.001; p = 0.01).

CONCLUSIONS

Hyperglycemia that requires insulin and exposure to more than three antibiotics are the factors associated with the development of candidemia in liver transplant recipients. When candidemia develops shortly after abdominal surgery and in patients with elevated AST, high white blood cell count, or low platelet count, it is associated with a high mortality rate.

Prevention and therapy of fungal infections in cancer patients. A review of recently published information

This review of recent publications in the field of fungal infections in cancer patients clearly confirms that protracted severe granulocytopenia is a major risk factor for their development. Because severe and prolonged granulocytopenia plays such a major predisposing role for fungal infections, it is likely that the use of the colony-stimulating factors, which are able to reduce the duration and the severity of granulocytopenia, might prove effective in decreasing the frequency and the severity of these infections. Another conclusion is that certain categories of patients with granulocytopenia might benefit from antifungal prophylaxis and empiric therapy. Conversely, there are other populations who will benefit only marginally from such strategies. Imidazoles, namely fluconazole, for the prevention of local and systemic Candida infections have been shown to be effective in granulocytopenic patients. So far, the development of resistance has not been a major problem. In patients at the greatest risk of developing severe fungal infections, such as those receiving high-dose corticosteroid therapy for GVHD after allogeneic bone marrow transplantation, early administration of low doses of amphotericin B seems to be effective in reducing the development of systemic fungal infection. In terms of therapy, amphotericin B is still the standard approach, especially for empiric treatment, prior to the recognition of a specific pathogen.

Current Approach to the Management of Neutropenia

Neutrophils have a critical role in host defense. Reduction in the absolute neutrophil count to below 1,000/μL is associated with increased susceptibility to infection. The pattern of infections depends on the severity and the duration of neutropenia and other associated defects in host defense mechanisms and exposure to antibiotics and other drugs, particularly corticosteroids and immunosuppressive agents. Breaks in the integrity of the skin or the gastrointestinal mucosal surfaces serve as the portals of entry for the majority of infecting organisms. Empiric antibiotic therapy and hospitalization are almost always required for the management of fever (temperature >38.2°C) in a neutropenic patient. A single antibiotic (e.g., ceftazidime or imipenem) or a combination of antibiotics with activity against both gram-positive and gram-negative organisms usually provides effective antimicrobial therapy. In low-risk patients, trials of out-patient therapy are ongoing. When febrile neutropenia does not respond to empiric broad-spectrum antibacterial therapy, fungal infections, particularly Candida and Aspergillus, should be considered, and antifungal therapy should be initiated. Recently, availability of the hematopoietic growth factors, particularly G-CSF and GM-CSF, have changed the approach to prevention and treatment of neutropenia. Randomized controlled studies have established that these growth factors accelerate hematopoietic recovery following chemotherapy and bone marrow transplantation. By shortening the duration of neutropenia, many of the heretofore inevitable problems with fever and infection can be avoided. The only major factor limiting the use of these agents is their cost. Despite the use of these growth factors, some patients will still experience slow hematopoietic recovery. For these patients, use of neutrophil transfusions, possibly from G-CSF-stimulated normal donors, may prove to be a useful adjunctive therapy.

Imipenem inhibits in vitro activity of amphotericin B directed against Aspergillus fumigatus

A decrease of the susceptibility of Aspergillus fumigatus strains to amphotericin B was found when tested in combination with high concentrations (128-2048 mg/l) of the antibacterial agent imipenem by checkerboard titration and agar diffusion assay. Only bacteriologically active imipenem showed the antagonism. The mechanism of action is unknown. However, imipenem and amphotericin B did not react directly, as shown by checkerboard titration with bacterial strains as well as by HPLC analysis. It is concluded that imipenem medication may influence the efficacy of amphotericin B treatment in aspergillosis.

Determination of amphotericin B in cerebrospinal fluid by solid-phase extraction and liquid chromatography

A highly sensitive and reproducible liquid chromatography (LC) method for the determination of Amphotericin B in cerebrospinal fluid has been developed and validated. This LC-based method involves using nystatin as an internal standard and solid-phase extraction for sample preparation, followed by reversed-phase separation monitored by absorbance at 410 nm. The method has a limit of quantification of less than 1 ng ml-1 and excellent precision and accuracy, with both percentage relative standard deviation and percentage relative error less than 10%. The established linearity range was 1-10 ng ml-1 (r2 > 0.99). The extraction recovery of Amphotericin B from the cerebrospinal fluid is higher than 90% over the entire linear range. The method has been successfully employed for studying the penetration of Amphotericin B into the central nervous system in dogs and human.

Population pharmacokinetics and renal function-sparing effects of amphotericin B colloidal dispersion in patients receiving bone marrow transplants

The purpose of this study was to evaluate the pharmacokinetics of amphotericin B colloidal dispersion and its effect on creatinine clearance in bone marrow transplant patients with systemic fungal infections. Seventy-five patients (42 females and 33 males) with a median age of 34.5 years and a median weight of 70.0 kg were enrolled in the study. Patients received 1 of 15 dose levels (range, 0.5 to 8.0 mg/kg of body weight) daily for a mean duration of 28 days and a mean cumulative dose amount of 8 g. Plasma samples for amphotericin B determination (median number, 4; range, 2 to 30) and daily serum creatinine values were obtained for each patient. Iterative two-stage analysis, one of several approaches to population pharmacokinetic and pharmacodynamic modelling, was employed for the pharmacokinetic analysis. The plasma data were available for 51 of 75 patients and were best described by a two-compartment model. Both plasma clearance and volume of distribution increased with escalating doses; the overall average terminal elimination half-life was 29 h. Of the covariates studied, only body weight and dose size were significant. Serum creatinine values over the duration of therapy were available for 59 of 75 patients. Overall, there was no net change in renal function over the duration of therapy; 12 patients had > 30% increases in creatinine clearance, whereas 13 had > 30% decreases. No measure of amphotericin B colloidal dispersion exposure, demographic values, or concomitant treatment with other medications was related to changes in the creatinine clearance.

Candida albicans meningitis in a 27 weeks premature infant treated with liposomal amphotericin-B (AmBisome)

We report a case of Candida albicans meningitis in a neonate born after 27 weeks of gestation. To the best of our knowledge this is the first report of a premature infant with Candida-meningitis treated with liposomal amphotericin B (AmBisome(R)). The patient did not respond well to conventional Amphotericin B, but was successfully cured with Ambisome(R). Liposomal amphotericin B was well tolerated and the baby recovered with a postinfectious hydrocephalus which necessitated a permanent ventriculo-peritoneal shunt. Six months after the infection the baby appears to have a near-normal cerebral development.

Selection of candidate quality control isolates and tentative quality control ranges for in vitro susceptibility testing of yeast isolates by National Committee for Clinical Laboratory Standards proposed standard methods

The National Committee for Clinical Laboratory Standards has developed a proposed standard method for in vitro antifungal susceptibility testing of yeast isolates (National Committee for Clinical Laboratory Standards, document M27-P, 1992). In order for antifungal testing by the M27-P method to be accepted, reliable quality control (QC) performance criteria must be developed. In the present study, five laboratories tested 10 candidate QC strains 20 times each against three antifungal agents: amphotericin B, fluconazole, and 5-fluorocytosine. All sites conformed to the M27-P standards and used a common lot of tube dilution reagents and RPMI 1640 broth medium. Overall, 98% of MIC results with amphotericin B, 95% with fluconazole, and 92% with 5-fluorocytosine fell within the desired 3-log2 dilution range (mode +/- 1 log2 dilution). Excellent performance with all three antifungal agents was observed for six strains: Candida albicans ATCC 90028, Candida parapsilosis ATCC 90018, C. parapsilosis ATCC 22019, Candida krusei ATCC 6258, Candida tropicalis ATCC 750, and Saccharomyces cerevisiae ATCC 9763. With these strains, 3-log2 dilution ranges encompassing 94 to 100% of MICs for all three drugs were established. Additional studies with multiple lots of RPMI 1640 test medium will be required to establish definitive QC ranges.

Multisite reproducibility of colorimetric broth microdilution method for antifungal susceptibility testing of yeast isolates

MICs of fluconazole and amphotericin B were determined independently for 100 coded yeast isolates by each of six laboratories to determine reproducibility of results by using a colorimetric oxidation-reduction-based broth microdilution test. In addition, each site tested five quality control isolates on at least four different occasions during the study. Results agreed within a three-dilution range (mode +/- 1 log2 dilution) for 96.2% of fluconazole tests and 92.7% of amphotericin B tests. Agreement among tests with the quality control isolates was 99.4% with fluconazole and 98.6% with amphotericin B. These results indicate that the colorimetric microdilution method is reproducible among laboratories.

Pulmonary sequestration in a child with acute myeloid leukemia

The article describes a relatively rare congenital anomaly that was difficult to diagnose in a 10-year-old child with acute nonlymphoblastic leukemia. Just at diagnosis of leukemia, the patient showed a pathologic chest radiograph because of a parenchymal thickening at the right lung apex. The presence of bronchopneumonia was suspected, and broad-spectrum antibiotic therapy was started with subsequent antifungal treatment for persistent fever and concurrent chemotherapy-induced marrow aplasia, which did not favor pulmonary infiltrate recovery. Continuous culture tests, including bronchial swab, proved negative for Koch-Weeks bacillus, fungal organisms, and other pathogens. Computed tomography, however, was suggestive of Aspergillus lung involvement, and apical segmentectomy was performed. The anatomic pathologist suggested the diagnosis of intralobar sequestration. In summary, when pulmonary pathology with an excavation is found in a leukemic child, one must consider the possibility of pulmonary sequestration complicated by an infectious disease.

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.

Amphotericin B versus amphotericin B plus 5-flucytosine: poor results in the treatment of proven systemic mycoses in neutropenic patients

Twenty-eight neutropenic (< 500 granulocytes/microliters) adults with microbiologically or histologically proven systemic mycosis were randomly assigned to receive either amphotericin B alone (0.5 mg/kg/day; n = 14) or amphotericin B (0.5 mg/kg/day) plus 5-flucytosine (150 mg/kg/day; n = 14) intravenously. Therapy was given for an average duration of 10 days in both groups, amounting to a total dose of amphotericin B of 338 mg and 308 mg, respectively. The mean duration of granulocytopenia was 18 days in the amphotericin B group and 20 days in the combination group. Only two patients treated with amphotericin B alone and three given the combination survived. Adverse events were similar in both groups with an elevation of the serum creatinine in six cases during the administration of amphotericin B alone and in seven cases treated with the combination. No other serious adverse events were encountered. Treatment with both regimens was disappointing partly because mycosis was too far advanced by the time therapy was begun and neutrophils were recovered in only half the patients.

In vitro susceptibility of Candida albicans, Austria 1992

A total of 38 isolates of Candida albicans were collected from clinical specimens and tested for minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) of amphotericin B, flucytosine and fluconazole. For amphotericin B and flucytosine all patients had isolates with MICs < or = 2 micrograms ml-1 and < or = 8 micrograms ml-1 respectively. For fluconazole all but two isolates had MICs < or = 16 micrograms ml-1. In vitro susceptibility testing remains problematic since standardized methods have not been established and the susceptibility and resistance ranges of MIC/MFC values still have to be defined in relation to in vivo data. Nevertheless, these results indicate that topical application of amphotericin B (more than 1 kg of amphotericin B per year at an intensive care unit performing selective digestive tract decontamination on certain trauma patients) had no major impact on the resistance patterns of C. albicans. In contrast, in this study both fluconazole-resistant isolates were from AIDS patients who were known to have received fluconazole therapy. Treatment with fluconazole--quite common in patients with AIDS--may produce resistant fungal isolates.

Diagnosis and treatment of invasive fungal infections in cancer patients

Fungal infections continue to cause major complications in cancer patients. With the increasing use of aggressive chemotherapy causing prolonged granulocytopenia, and the progress made in the prophylaxis and treatment of bacterial infections, the risk of invasive mycoses has increased, particularly in patients with hematological malignancies. The prognosis of these infections is poor unless they are diagnosed and treated promptly. Early diagnosis, particularly in neutropenic cancer patients, is often difficult and antifungal therapy is frequently unsuccessful because it is not instituted until the infection is in an advanced, fatal phase. In order to reduce the mortality associated with invasive fungal infections, antifungal therapy, usually amphotericin B, has been empirically carried out in neutropenic patients with fever unresponsive to broad-spectrum antibacterial therapy. However, the absence of a marker of the fungal infection, the frequent occurrence in these patients of non-infective fever, which does not require any antimicrobial therapy, and the possible toxicity of amphotericin B represent the major limits of empiric antifungal therapy. In view of the above, the study of improved and less toxic antifungal agents, and the evaluation of new clinical and laboratory methods for an early diagnosis, have been the major goals in research on the opportunistic invasive fungal infections in the last years.

Comparative efficacies of cilofungin (Ly121019) and amphotericin B against disseminated Candida albicans infection in normal and granulocytopenic mice

The efficacies of cilofungin (Ly121019), a semisynthetic lipopeptide antifungal agent, and amphotericin B in the treatment of disseminated candidiasis in normal and neutropenic mice were compared. In mice infected with 2 x 10(6) CFU of Candida albicans, treatment with cilofungin in twice-daily doses of 25 or 35 mg/kg of body weight by intraperitoneal injection for 10 days gave survival rates of 83 and 90%. In contrast, there was 97% mortality in infected controls receiving 2 x 10(6) CFU intravenously and 93% survival in mice treated with 1 mg of amphotericin B per kg once a day. Mice rendered granulocytopenic by the administration of cyclophosphamide showed survival rates of 83 and 80% when treated with 25 or 35 mg of cilofungin per kg for 10 days compared with 43% survival rate in mice treated with 1 mg of amphotericin B per kg (P = 0.0030 and P = 0.0080, respectively). Similar results were obtained when the two antifungal agents were administered for a period of 30 days. Administration of 25 or 35 mg of cilofungin per kg twice a day to granulocytopenic mice receiving 10(6) CFU of C. albicans gave survival rates of 93% and 93% compared with 53% survival with amphotericin B. With 15 mg of cilofungin per kg twice a day for 10 days, a survival rate of 43 to 50% was observed in both normal and granulocytopenic mice compared with 56 and 60%, respectively, when this dosage was continued for 30 days. Cilofungin eradicated C. albicans from the kidneys, spleens, and livers of surviving animals. No toxic effects were observed with any of the dosage regimens used. The clearance of C. albicans from the kidneys, spleens, livers, and brains in normal mice was studied following infection with 5 x 10(5) and 1 x 10(5) intravenously. The mice in the treatment groups received 25 mg of cilofungin per kg twice a day for 10 days. In 8 to 12 days, this treatment was able to clear the organisms from the kidneys, spleens, and livers of mice infected with 5 x 10(5) C. albicans. Mice infected with 10(5) C. albicans and treated with cilofungin (25 mg/kg) twice a day for 10 days had no organisms in the kidney, spleen, and liver at days 8, 2, and 8, respectively. There was 1-log-unit reduction in C. albicans counts in brain tissue from mice of one of the treated groups between 2 h and 2 days postinfection, after which the numbers of organisms remained the same until day 12. These data demonstrate the efficacy of cilofungin in the treatment of disseminated C. albicans infections in normal and granulocytopenic mice. The treatment regimen used in this study was able to clear C. albicans from the kidneys, spleen, and liver but not from brain tissue.

Standardized susceptibility testing of fluconazole: an international collaborative study

An international collaborative study of broth dilution (MIC) and disk diffusion susceptibility testing of fluconazole was conducted by using a chemically defined medium (High-Resolution Antifungal Assay Medium; Oxoid Ltd., Basingstoke, United Kingdom) and standard test methods performed in eight reference laboratories. Ten yeast isolates were tested by each test method in duplicate on each of 3 separate days. The intralaboratory reproducibility of the MIC test was excellent; 95.7% of the replicate tests (n = 220) were within 2 doubling dilutions of the other values in the set for the eight laboratories. The intralaboratory reproducibility of the disk test was also good, with 91% of the replicate tests (n = 234) agreeing with each other within an arbitrarily chosen value of 4 mm. Interlaboratory agreement of MIC test results was acceptable, with 84% of the MICs agreeing within 2 doubling dilutions. In contrast, the interlaboratory agreement of the disk test was not good, with only 59% of test results agreeing within 4 mm. Comparison of the rank order of MICs obtained in each laboratory with the reference rank order gave an agreement of 70 to 80% (median, 80%) with the MIC test and 70 to 90% (median, 80%) with the disk test. These preliminary results are encouraging for the development of standardized testing methods for testing fluconazole.

Oral candidosis. Clinical, historical, and therapeutic features of 100 cases

Oral candidosis is an increasingly important disease that affects a significant percentage of the population. Traditionally known as an opportunistic pathogen, the broader clinical scope of oropharyngeal candidal infections is now being recognized. The clinical and historical features of 100 patients referred for diagnosis and management of candidosis have been reviewed. The age, gender, chief complaint, medical history, medications, and clinical findings have been noted. A wide range of clinical signs and symptoms, and the rationale behind the topical and systemic antifungal therapies provided to this patient population, are discussed.

Chronic systemic candidiasis in acute leukemia

In the past few years a new syndrome of invasive Candida infection, the so-called hepatosplenic or chronic systemic candidiasis (CSC), has been recognized with increasing frequency in neutropenic patients. From January 1985 to December 1990, ten of 305 acute leukemia (AL) patients treated at our institution were diagnosed as having CSC. In contrast, during the same period this type of Candida infection was not observed in any patient with hematological diseases other than AL treated in our center, including 277 patients who underwent bone marrow transplantation. All patients with CSC had fever and hepatomegaly, and five complained of abdominal pain. Seven patients had neutrophilic leukocytosis and six an increased serum alkaline phosphatase activity. Abdominal computed tomography and ultrasound study showed typical lesions in eight and seven patients, respectively. In four patients a laparoscopy-guided needle liver biopsy displayed yellowish nodules on the liver surface, and the histologic study revealed large granulomas with yeasts and pseudohyphae. All patients were given amphotericin B (mean: 4.6 g, range: 1-12.5 g) and 5-fluorocytosine, and five received fluconazole. No patient died as a direct consequence of CSC and in six the infection resolved. Finally, once controlled, the infectious complication did not preclude subsequent intensive antileukemic therapy, including bone marrow transplantation.

Efficacy of fluconazole in the treatment of systemic fungal infections

The efficacy of fluconazole in the treatment of systemic fungal infections was evaluated in an open non-comparative trial. A total of 48 patients with proven or suspected fungal infections were enrolled in 40 of whom efficacy was evaluable. Candida albicans accounted for 90% of the infections. Candida parapsilosis, Candida glabrata, Histoplasma capsulatum and Aspergillus fumigatus caused the infection in one case each. Fluconazole was administered at a dosage of 200-400 mg daily for a mean duration of 15 days. Fluconazole treatment was successful in 53% of the patients. In patients with proven or probable Candida albicans infections a clinical and mycological response was achieved in 62% and 65%, respectively. In 11 patients elevation of liver enzymes was considered to be possibly related to fluconazole treatment; modification of treatment was not necessary in any case. Fluconazole was found to be a well tolerated and effective agent for the treatment of systemic Candida albicans infections.

Impact of the changing epidemiology of fungal infections in the 1990s

The increase in fungal infections over the past decade is striking. This is particularly true for hospitalized patients where the rate of candidal bloodstream infection has increased by as much as 487% over the decade of the 1980s. This increase in fungal infections is accompanied by a significant excess mortality and excess length of stay in hospital. The emergence of "new" fungal pathogens such as Candida krusei, Torulopsis glabrata, Fusarium and Trichosporon beigelii is now recognized as a significant problem in many patient populations. The documentation of nosocomial transmission of fungal pathogens and the recognition of resistance to both new and established anti-fungal agents poses a significant problem entering the 1990s. Continued effort is needed to develop new and better therapeutic agents and more effective strategies for prophylaxis of endogenous infections and prevention of transmission within the hospital setting.

Antifungal agents used for deep-seated mycotic infections

The increased use of immunosuppressive regimens in organ transplantation and in the treatment of malignant lesions and the epidemic of acquired immunodeficiency syndrome (AIDS) are major reasons for the greater prevalence of fungal infections seen in clinical practice during the past decade. The traditional cornerstone of antifungal treatment, amphotericin B, continues to play a major role in deep-seated mycotic infections. The indications for intravenously administered miconazole have become limited. Orally administered flucytosine remains useful in certain infections, particularly cryptococcal meningitis. The new orally administered antifungal agents ketoconazole and fluconazole have been approved for clinical use and have supplanted amphotericin B in certain situations. Investigational antifungal agents, including liposomal amphotericin B, itraconazole, and saperconazole, hold promise for the future. Active investigation in the development of new antifungal agents is expected to continue.

Comparison of fluconazole and amphotericin B for prevention and treatment of experimental Candida endocarditis

Fluconazole and amphotericin B were compared in the prophylaxis and treatment of Candida albicans aortic endocarditis in a rabbit model. In the prophylaxis study, catheterized rabbits received, prior to intravenous (i.v.) challenge with C. albicans (2 x 10(7) blastospores), either no therapy, single-dose i.v. amphotericin B (1 mg/kg of body weight), single-dose fluconazole (50 mg/kg or 100 mg/kg i.v. or intraperitoneally [i.p.]), or fluconazole (50 mg/kg or 100 mg/kg i.v. or i.p.) with a second dose 24 h after inoculation. A single dose of amphotericin B was significantly more effective than either the one- or two-dose regimens of fluconazole at both 50 mg/kg (P less than 0.001 and P less than 0.03, respectively) and 100 mg/kg (P less than 0.01 and P less than 0.001, respectively) in the prevention of C. albicans endocarditis. In parallel treatment studies of established C. albicans endocarditis, i.v. amphotericin B (1 mg/kg) or i.p. fluconazole (50 mg/kg) was begun 24 or 60 h postinfection and continued daily for 9 or 12 days. At these dose regimens, amphotericin B was consistently more effective than fluconazole in reducing fungal vegetation densities, regardless of the timing of initiation of therapy. We also examined the efficacy of fluconazole at a daily dose of 100 mg/kg i.p. administered for 21 days in the treatment of established C. albicans endocarditis. When therapy was continued for 2 weeks or longer, fluconazole was more effective than no drug and approximately twice as effective as 12 days of amphotericin B in reducing intravegetation fungal densities. Our results suggest that amphotericin B is superior to fluconazole in both the prophylaxis and treatment of C. albicans endocarditis in the rabbit model. These findings may relate to the predominantly fungistatic activity of fluconazole against C. albicans in vitro.

Effects of amphotericin B and fluconazole on the extracellular and intracellular growth of Candida albicans

The effects of amphotericin B and fluconazole on the extracellular and intracellular growth of Candida albicans were studied. With respect to the extracellular growth of C. albicans, antifungal activity was measured in terms of MICs and minimal fungicidal concentrations as well as by determination of the concentration that effectively killed (greater than 99.9%) C. albicans in the absence or presence (amphotericin B only) of serum. Amphotericin B was highly active in terms of killing, even at an increased inoculum size. In the presence of serum, amphotericin B activity was substantially reduced. For fluconazole, activity was restricted to inhibition of fungal growth, even after the inoculum size was reduced. With respect to the intracellular growth of C. albicans, antifungal activity was measured by using monolayers of murine peritoneal macrophages infected with C. albicans and was measured in terms of inhibition of germ tube formation as well as effective killing (greater than 99%) of C. albicans. Amphotericin B was highly active against C. albicans. At an increased ratio of infection, amphotericin B activity was slightly reduced. Fluconazole had no antifungal activity. Neither a reduction in the ratio of infection nor exposure of C. albicans to fluconazole prior to macrophage ingestion resulted in activity against intracellular C. albicans by fluconazole. Previous exposure of C. albicans to amphotericin B resulted in increased intracellular activity of amphotericin B. The intracellular antifungal activity of the combination of fluconazole with amphotericin B was less than that of amphotericin B alone. Amphotericin B showed fungicidal activity against C. albicans growing both extracellularly and intracellularly, whereas fluconazole inhibited growth only of extracellular C. albicans. A slight antagonistic effect between fluconazole and amphotericin B was found with respect to intracellular as well as extracellular C. albicans.

Fluconazole susceptibility testing of Candida albicans: microtiter method that is independent of inoculum size, temperature, and time of reading

In vitro antifungal susceptibility testing generally remains unstandardized and unreliable for directing therapy. When azoles are tested, this problem is further compounded by the lack of definite reading end points. We determined the in vitro susceptibility of 50 Candida albicans isolates (including 10 reference strains) to fluconazole by using a microbroth dilution method in which microtiter plates were agitated immediately before reading. Six fungal inoculum sizes (ranging from 2 x 10(2) to 4 x 10(5) CFU/ml), three different times of reading (24, 48, and 72 h), and two temperatures (30 and 35 degrees C) were tested. We also compared visual and spectrophotometric determinations of MIC end points. This agitation method resulted in clear-cut visual end points that were reproducible for different observers within the same laboratory, that were independent of inoculum size, temperature of incubation, and time of reading, and that correlated well with the degree of fungal inhibition as determined by spectrophotometry. Median MICs also correlated with usually achievable levels of fluconazole in serum and tissue of humans and experimental animals.

Fluconazole therapy for chronic disseminated candidiasis in patients with leukemia and prior amphotericin B therapy

OBJECTIVE

To study the efficacy of fluconazole against chronic disseminated candidiasis (hepatosplenic candidiasis) in patients with leukemia in whom amphotericin B treatment had failed.

DESIGN

Retrospective analysis of patients with chronic disseminated candidiasis treated with fluconazole on a compassionate investigational new drug protocol.

SETTING

Multi-institutional.

PATIENTS AND METHODS

Twenty consecutive patients received 100 to 400 mg of fluconazole per day for a median of 30 weeks. All had either failed to respond to treatment with more than 2 g of amphotericin B or had serious amphotericin B-related toxicities.

RESULTS

Fourteen of 16 evaluable patients (88%) responded. Responses were observed in seven of nine patients in whom adequate doses of amphotericin B had failed and in all seven patients who had amphotericin B-related toxicities. In 12 patients, cytotoxic chemotherapy was continued without flare of the infection. Fluconazole was well tolerated with rare side effects. Aspergillus superinfection developed in three patients and contributed to the death of two of them.

CONCLUSION

Fluconazole is a safe and effective agent with significant activity against chronic disseminated candidiasis.

Safety and efficacy of fluconazole treatment for Candida oesophagitis in AIDS

The efficacy and safety of fluconazole in the treatment of oesophageal candidiasis in patients with the acquired immunodeficiency syndrome (AIDS) was assessed in 36 patients. Fluconazole, 200 mg orally, was given on the first day, followed by 100 mg daily for 4 weeks. Clinical and mycological evaluation was performed in 31 patients at the end of treatment and 24 were also assessed after 8 weeks of starting treatment. In 1 patient fluconazole was discontinued, 5 patients were lost to follow-up and 6 patients died during the study. Clinical and mycological cure was achieved in all patients; in 31 of 36 patients the clinical picture resolved within a week. The cure was confirmed in 27 patients by oesophagoscopy. Two patients relapsed 1 month after stopping fluconazole but the reinstitution of therapy achieved cure. Asymptomatic fungal oropharynx colonization was evident in about 40% of patients during treatment and follow-up period. Fluconazole was well tolerated by all patients but mild to moderate increase of liver enzymes values occurred in 16. Treatment had to be discontinued in 1 patient with hepatic tuberculosis because of severe liver function abnormalities, but their relation with the drug was uncertain. Fluconazole is an effective and safe treatment of oesophageal candidiasis in AIDS patients.

Single-dose pharmacokinetics and tolerance of a cholesteryl sulfate complex of amphotericin B administered to healthy volunteers

Twenty-three healthy volunteer subjects received a single dose of amphotericin B colloidal dispersion or placebo (4:2) in a double-blind, randomized, dose-escalating design. Doses ranged from 0.25 to 1.5 mg/kg of body weight. The medication was administered via intravenous infusion at a rate of 0.5 mg/kg/h. Plasma amphotericin B concentrations increased with increasing doses, resulting in a linear increase in the amphotericin B area under the curve. Concentrations in plasma decreased rapidly upon discontinuation of the infusion, indicating rapid tissue distribution. A log-linear biexponential elimination phase was observed. A three-compartment open model was used to describe the distribution and elimination of amphotericin B. The mean terminal elimination half-life ranged from 86 h at the 0.25-mg/kg dose level to 244 and 235 h at the 1.0- and 1.5-mg/kg dose levels, respectively. Mean total body clearance ranged from 219 to 284 ml/kg/h. The volume of distribution increased with dose, from 3.37 liter/kg at the 0.25-mg/kg dose to 7.92 liter/kg at the 1.5-mg/kg dose. At the lowest dose level, 0.25 mg/kg, the medication was generally well tolerated. Progressive increases in the dose led to increasing side effects. At the 1.5-mg/kg dose level, 50% of the patients on active medication experienced nausea, vomiting, and chills. Physical examinations, ophthalmologic examinations, and clinical laboratory parameters remained within normal limits compared with those obtained during prestudy examinations.

Fluconazole. Review and situation among antifungal drugs in the treatment of opportunistic mycoses of human immuno-deficiency virus infections

Fluconazole is a novel triazole antifungal drug chiefly used in the treatment of opportunistic mycoses in immuno-compromised patients, particularly those with the acquired immuno-deficiency syndrome (AIDS). In comparison with other antifungal drugs, fluconazole has outstanding physical and pharmacokinetic properties, such as an excellent aqueous solubility allowing a parenteral formulation, high bioavailability by the oral route, even distribution throughout the tissues, including the central nervous system and the cerebro-spinal fluid, a long half-life (permitting once daily administration), and low binding to plasma proteins. It is excreted mainly as unchanged drug in the urine. Fluconazole is a broad-spectrum antifungal agent, especially effective against Candida spp., Cryptococcus neoformans and dermatophytes. Its antifungal efficacy was mainly proved by testing in animal models, since there is no relationship between in vitro and in vivo activities. It possesses a low toxicity and it is well-tolerated. Fluconazole is currently marketed for the treatment of oropharyngeal candidiasis in immuno-compromised patients and of atrophic oral candidiasis. Its place in the treatment of opportunistic mycoses in human immuno-deficiency virus-positive patients, in particular cryptococcal meningitis, is still under investigation but is promising.

Comparison of fluconazole and amphotericin B for treatment of disseminated candidiasis and endophthalmitis in rabbits

We compared the efficacy of intravenous fluconazole (80 mg/kg of body weight per day) with that of amphotericin B (1 mg/kg/day) for the long-term treatment of endophthalmitis in rabbits with disseminated candidiasis. After 17 days of therapy, fluconazole decreased the fungal colony counts of the choroid-retinas significantly more than did the saline control (P less than 0.05); however, after 24 days of fluconazole therapy, this treatment effect was lost and fluconazole was no more effective than saline. In contrast, treatment for 24 days with amphotericin B reduced the vitreous and choroid-retina fungal colony counts significantly more than either fluconazole or saline (P less than 0.05 for both treatment groups). After 17 days of therapy, indirect ophthalmoscopy revealed less severe eye involvement in both antifungal treatment groups than in saline controls; however, this difference reached statistical significance only for the amphotericin B-treated rabbits (P less than 0.05). Also, there was a trend towards worsening eye lesions, as seen by indirect ophthalmoscopy, in the fluconazole-treated rabbits after 24 days of therapy, which roughly paralleled the quantitative culture results. Despite the presence of negative choroid-retina cultures, some rabbits in all treatment groups had persistently visible eye lesions, indicating that ophthalmoscopic resolution of Candida endophthalmitis may lag behind lesion sterilization. Amphotericin B was superior to fluconazole in the treatment of Candida endophthalmitis in this model.

In-vitro comparative activity of fluconazole and other antifungal agents against Blastoschizomyces capitatus

Blastoschizomyces capitatus represents an emerging fungal pathogen in acute leukemia patients. The susceptibility to amphotericin B, 5-fluorocytosine, ketoconazole and fluconazole of nine clinical isolates was evaluated. A specific medium (high resolution medium) was used for testing fluconazole. This agent and 5-fluorocytosine were at least four- to eight-fold more active than amphotericin B and ketoconazole against all isolates but one.

Cilofungin (LY121019) shows nonlinear plasma pharmacokinetics and tissue penetration in rabbits

We studied the plasma pharmacokinetics and tissue penetration of cilofungin (LY121019), a new echinocandin antifungal compound, by intermittent and continuous infusion in rabbits. Following a single intravenous dose of 50 mg/kg of body weight, the maximum concentration in plasma was 297 +/- 39 micrograms/ml, the area under the curve was 30.1 +/- 6.7 micrograms.h/ml, clearance was 30 +/- 10 ml/min/kg, volume of distribution was 0.85 +/- 0.23 liters/kg, half-life in distribution phase was 3.7 +/- 0.2 min (first 12 min postdose), and half-life in elimination phase was 12.9 +/- 0.7 min. When rabbits received cilofungin by continuous infusion (CI) at 10 mg/kg/h over 6 days, sustained concentrations in plasma of 290 +/- 56 micrograms/ml were seen, more than 50-fold higher than predicted if kinetics were linear. Similarly, at 5 mg/kg/h, high levels were also obtained. Such elevated levels in plasma would not have been predicted from the pharmacokinetic characteristics of cilofungin given as a single intravenous dose. Further pharmacokinetic study at several rates of CI suggested that cilofungin elimination follows Michaelis-Menten kinetics. Simultaneous cilofungin levels in plasma and tissue were then determined for rabbits receiving six intravenous, intermittent doses (ID) of cilofungin at 15 mg/kg every 4 min and for rabbits receiving CI as described above. After ID, the mean of the ratios of cilofungin levels in tissue to those in plasma were highest for liver and bile but very low for cerebrum and cerebellum. After CI, ratios were as much as 89 times higher than for ID and significantly greater in the brain, choroid, kidney, and bile (P less than 0.05). We conclude that following a single dose of cilofungin, the compound is rapidly cleared via first-order kinetics and does not penetrate into the central nervous system, whereas following CI, cilofungin exhibits nonlinear saturable kinetics, is slowly cleared, and significantly penetrates into central nervous system tissues.

Activity of amphotericin B and intraconazole against intraphagocytic Candida albicans

The activity of amphotericin B and intraconazole against intracellular Candida albicans was determined in vitro using murine resident peritoneal macrophages. Amphotericin B at concentrations of 0.5 and 2 micrograms/ml produced significantly less rapid killing of intracellular than of extracellular Candida albicans as measured in macrophage-free medium. Amphotericin B at concentrations of 0.1 micrograms/ml or itraconazole concentrations of up to 3 micrograms/ml produced only fungistatic or limited fungicidal activity against both intracellular and extracellular organisms. Against intracellular Candida albicans amphotericin B acted by direct antifungal action rather than through stimulation of macrophage function, as demonstrated by the fact that (i) activity persisted when macrophages were successively exposed to amphotericin B, washed and disrupted by sonication, and (ii) no activity was seen when amphotericin B was tested against intracellular amphotericin B-resistant Candida tropicalis or Salmonella typhimurium. Pre-exposure of macrophages to itraconazole (0.4 micrograms/ml) inhibited subsequent killing activity of amphotericin B (2 micrograms/ml) against intracellular susceptible Candida albicans. These experiments validate the conventional methods of susceptibility testing for determining the fungistatic activity of antifungal agents.

Effects of antifungal agents on the function of human neutrophils in vitro

Polymorphonuclear leukocytes (PMNs) are an important component of the host defense against fungi. We investigated the influence of five antifungal agents on PMN function and compared them with amphotericin B (AmB). The in vitro effects of AmB, flucytosine, ketoconazole, fluconazole, Sch-39304, and cilofungin (LY121019) on chemotaxis, phagocytosis, oxidative metabolism of PMN as reflected by superoxide anion (O2-) generation, and intracellular killing of Candida albicans blastoconidia were examined. With regard to chemotaxis in response to N-formylmethionyl-leucyl-phenylalanine, as measured by the multiwell chamber method, AmB induced a marked decrease (greater than or equal to 5 micrograms/ml), whereas ketoconazole at 5 micrograms/ml enhance it. Phagocytosis was significantly decreased after pretreatment of PMNs with AmB and Sch-39304 (greater than 5 and 1 to 10 micrograms/ml, respectively). O2- production after stimulation of PMNs with N-formylmethionyl-leucyl-phenyl-alanine was significantly decreased by AmB (greater than 5 micrograms/ml) and enhanced by Sch-39304 (1 to 5 micrograms/ml). In contrast, intracellular killing, as tested by methylene blue staining, was enhanced by ketoconazole (5 micrograms/ml) and Sch-39304 (1 to 5 micrograms/ml). Flucytosine, fluconazole, and cilofungin did not affect PMN function at therapeutic concentrations. The results of this comprehensive study indicate that AmB, flucytosine, cilofungin, and the newer azoles, at safely achievable concentrations, generally do not suppress PMN function at therapeutic enhance selective functions.

Topical fluconazole for experimental candida keratitis in rabbits

Using a reproducible model of Candida albicans keratitis in rabbits we studied the effect of topical fluconazole, a new triazole. Candida albicans DSM 70010 (2.5 X 10(5) cells) was injected into the corneal stroma of both eyes of 21 rabbits. All eyes developed a corneal ulcer. Forty-eight hours after inoculation the animals were divided into three groups: (1) 14 eyes, received fluconazole (2 mg/ml) and the epithelium subsequently removed; (2) 14 eyes, received only fluconazole drops; (3) 14 eyes, received 0.9% NaCl: half of this group was also debrided. We applied one drop of either substance 10 times a day for 24 days. A further six rabbits were used to judge if the drug penetrated into the cornea and aqueous humour. There was a highly significant difference between the fluconazole groups (1,2) and the control group (3) as to hypopyon and complications (descemetocele, corneal perforation) as well as recultivation of C. albicans from corneal tissue. The difference between the fluconazole groups with and without debridement was not significant. The drug penetrated into the cornea and aqueous humour of both uninflamed and inflamed eyes.