Combination Of Amphotericin Research Articles

Effect of neutropenia and treatment delay on the response to antifungal agents in experimental disseminated candidiasis.

Disseminated candidiasis is associated with a high rate of morbidity and mortality. The presence of neutrophils and the timely administration of antifungal agents are likely to be critical factors for a favorable therapeutic outcome of this syndrome. The effect of neutropenia on the temporal profile of the burden of Candida albicans in untreated mice and those treated with amphotericin B was determined using a pharmacodynamic model of disseminated candidiasis. A mathematical model was developed to describe the rate and extent of the C. albicans killing attributable to neutrophils and to amphotericin B. The consequences of a delay in the administration of amphotericin B, flucytosine, or micafungin were studied by defining dose-response relationships. Neutrophils caused a logarithmic decline in fungal burden in treated and untreated mice. The combination of amphotericin B and neutrophils resulted in a high rate of Candida killing and a sustained anti-C. albicans effect. In neutropenic mice, 5 mg/kg of body weight of amphotericin B was required to prevent progressive logarithmic growth. An increased delay in drug administration resulted in a reduction in the maximum effect to a point at which no drug effect could be observed. Neutrophils and the timely initiation of antifungal agents are critical determinants in the treatment of experimental disseminated candidiasis.

Combination of Amphotericin B with Flucytosine Is Active In Vitro against Flucytosine-Resistant Isolates of Cryptococcus neoformans

The combination of flucytosine and amphotericin B was tested against 10 flucytosine-resistant isolates of Cryptococcus neoformans by checkerboard, killing curves, and Etest. Although differences were observed depending on the technique used, antagonism was never observed. The synergistic interaction was related to the mechanism of flucytosine resistance of the isolates.

Candida albicans Biofilms Produce Antifungal-Tolerant Persister Cells

Fungal pathogens form biofilms that are highly recalcitrant to antimicrobial therapy. The expression of multidrug resistance pumps in young biofilms has been linked to increased resistance to azoles, but this mechanism does not seem to underlie the resistance of mature biofilms that is a model of in vivo infection. The mechanism of drug resistance of mature biofilms remains largely unknown. We report that biofilms formed by the major human pathogen Candida albicans exhibited a strikingly biphasic killing pattern in response to two microbicidal agents, amphotericin B, a polyene antifungal, and chlorhexidine, an antiseptic, indicating that a subpopulation of highly tolerant cells, termed persisters, existed. The extent of killing with a combination of amphotericin B and chlorhexidine was similar to that observed with individually added antimicrobials. Thus, surviving persisters form a multidrug-tolerant subpopulation. Interestingly, surviving C. albicans persisters were detected only in biofilms and not in exponentially growing or stationary-phase planktonic populations. Reinoculation of cells that survived killing of the biofilm by amphotericin B produced a new biofilm with a new subpopulation of persisters. This suggests that C. albicans persisters are not mutants but phenotypic variants of the wild type. Using a stain for dead cells, rare dark cells were visible in a biofilm after amphotericin B treatment, and a bright and a dim population were physically sorted from this biofilm. Only the dim cells produced colonies, showing that this method allows the isolation of yeast persisters. Given that persisters formed only in biofilms, mutants defective in biofilm formation were examined for tolerance of amphotericin B. All of the known mutants affected in biofilm formation were able to produce normal levels of persisters. This finding indicates that attachment rather than formation of a complex biofilm architecture initiates persister formation. Bacteria produce multidrug-tolerant persister cells in both planktonic and biofilm populations, and it appears that yeasts and bacteria have evolved analogous strategies that assign the function of survival to a small part of the population. In bacteria, persisters are dormant cells. It remains to be seen whether attachment initiates dormancy that leads to the formation of fungal persisters. This study suggests that persisters may be largely responsible for the multidrug tolerance of fungal biofilms.

PI-81Modeling of the three antifungal agent combination (Amphotericin B+ Micafungin+ Nikkomycin Z) against Aspergillus fumigatus in vitro using a novel response surface paradigm

PI-81Modeling of the three antifungal agent combination (Amphotericin B+ Micafungin+ Nikkomycin Z) against Aspergillus fumigatus in vitro using a novel response surface paradigm

Efficacy of Amphotericin B in Combination with Flucytosine against Flucytosine-Susceptible or Flucytosine-Resistant Isolates of Cryptococcus neoformans during Disseminated Murine Cryptococcosis

Whether or not flucytosine should be administered to patients infected with Cryptococcus neoformans isolates found to be resistant to flucytosine in vitro remains a controversial issue. Thus, the efficacy of amphotericin B and flucytosine in combination was investigated by mortality and fungal burden studies in a murine model of disseminated cryptococcosis using two clinical isolates of Cryptococcus neoformans, one susceptible and one resistant (i.e., 64 microg/ml) to flucytosine. Amphotericin B was given intraperitoneally at 0.25 or 0.5 mg/kg/day, while flucytosine was given at 100 or 250 mg/kg/day orally. Treatment was started 24 h or day 6 after inoculation and continued for 5 days in fungal burden and mortality studies, respectively. The combination of amphotericin B at 0.5 mg/kg/day and flucytosine at 250 mg/kg/day was significantly more effective than monotherapies for reducing fungal burden in brain, spleen, and lungs after infection by the flucytosine-susceptible isolate and in brain and spleen for the flucytosine-resistant isolate. For the flucytosine-resistant isolate, the combination of amphotericin B at 0.5 mg/kg/day with flucytosine at 100 mg/kg/day was significantly better than monotherapies for reducing the fungal burden in the brain. Survival obtained after the combination of amphotericin B at 0.5 mg/kg/day and flucytosine at 250 mg/kg/day increased compared to that obtained with monotherapies for both isolates, but the difference was statistically significant only for the flucytosine-susceptible isolate. Antagonism was never observed. This study demonstrates the beneficial effect of the addition of flucytosine to amphotericin B against experimental disseminated cryptococcal infection even when the C. neoformans isolate is resistant to flucytosine.

Zygomycosis: An emerging fungal infection

The epidemiology, pathogenesis, clinical presentation and diagnosis, and management of zygomycosis are reviewed. The frequency of zygomycosis has been increasing over the past 10 years; infections have been identified in up to 6.8% of patients at autopsy. The most common route of transmission for Zygomycetes fungi is inhalation of spores from the environment. Patients at highest risk for infections caused by Mucorales fungi include those with profound immunosuppression or diabetes, intravenous drug abusers, premature infants, those receiving deferoxamine, and recipients of bone marrow transplants. Mucormycosis commonly presents as rhinocerebral or pulmonary disease; gastrointestinal presentations also occur. Clinical manifestations of invasive mucormycosis are tissue necrosis and subsequent thrombosis. Common features of pulmonary disease include fever, dyspnea, hemoptysis, and cavitation upon radiologic examination. The mainstays of treatment are control or reversal of the underlying disease or immunosuppression, antifungal therapy, and aggressive surgical debridement. Posaconazole, a new triazole antifungal, has been used successfully in a number of cases that did not respond to amphotericin B. Zygomycosis appears to be on the rise in the United States. The standard treatment is a combination of amphotericin B therapy, surgical debridement, and reversal of the underlying disease or immunosuppression.

Tricuspid Valve Repair in an Infant With Multiple Obstructive Candida Mycetomas

Neonatal fungal valve endocarditis is an uncommon and highly lethal disease. The ideal management strategy is still controversial. Current options include antifungal chemotherapy and surgical intervention, the latter being often limited by risks inherent with valve operations in low body weight infants. We present a case of a premature infant with multiple Candida tricuspid valve mycetomas. Eradication of infection was achieved by combined liposomal amphotericin therapy and complex tricuspid valve repair. Indications, technical aspects, and outcome of treatment in infants are reviewed.

A case of chromoblastomycosis with an unusual clinical manifestation caused by Phialophora verrucosa on an unexposed area: treatment with a combination of amphotericin B and 5-flucytosine

Chromoblastomycosis is a cutaneous and subcutaneous mycotic disease caused by the dematiaceous (black) fungi. Five species of fungi are known generally to be the cause: Fonsecaea pedrosoi, Phialophora verrucosa, Cladosporium carrionii, F. compacta and Rhinocladiella cerphilum. In infected tissue they can appear as pigmented sclerotic bodies, commonly called 'copper pennies', which are pathognomonic of chromoblastomycosis. The infection usually occurs through traumatic skin inoculation, with the majority of lesions occurring on the feet and legs of outdoor workers. We report a patient in whom the lesions had begun on the right breast, which is an unexposed area, without a history of trauma. A uniform, reliable treatment does not exist but our patient was mycologically cured with the use of amphotericin B and the subsequent combination of 5-flucytosine and itraconazole.

Emergence of disseminated candidiasis caused byCandida kruseiduring treatment with caspofungin: Case report and review of literature

Current data indicate that caspofungin has in vitro activity against virtually all Candida species. However, we report herein a case of disseminated candidiasis due to Candida krusei which emerged during caspofungin treatment. Lung and brain secondary sites were then successfully treated using a combination of amphotericin B plus flucytosine, amphotericin B lipid complex, and voriconazole, sequentially. Among the total of four well documented cases of refractory invasive candidiasis during caspofungin therapy, the common risk factors appear to involve prior abdominal surgery, persistent foreign body, and anatomical sites where drug concentrations may be sub-optimal for Candida species with increased MICs. Caspofungin failure should be suspected in patients with persistent or emergent signs and symptoms of deep-seated invasive candidiasis.

Evaluation of Mycograb®, amphotericin B, caspofungin, and fluconazole in combination against Cryptococcus neoformans by checkerboard and time-kill methodologies

This article reported the identification of heat shock protein 90 (hsp90) homologues by immunoblot in Cryptococcus neoformans. Mycograb®, a genetically recombinant antibody against hsp90, was evaluated against 8 clinical isolates and the National External Quality Assessment Service for Microbiology strain of C. neoformans alone and in combination with amphotericin B, caspofungin, and fluconazole by checkerboard assay. At the end point of an optically clear well, the minimum inhibitory concentration (MIC) 0's ranged from 256 to 1024 μg/mL for Mycograb®, from 0.5 to 1 μg/mL for amphotericin B, and from 16 to 32 μg/mL for caspofungin. The combination of Mycograb® and amphotericin B produced a fractional inhibitory concentration index from 0.27 to 0.56, indicating a mainly synergistic effect, whereas for caspofungin, it varied from 0.5 to 2. At an end point of ≥50% inhibition, the MIC-2s varied from 16 to 128 μg/mL for Mycograb® and from 0.125 to 16 μg/mL for fluconazole. The fractional inhibitory concentration index classified the combination as indifferent for 5 isolates, additive for 3 more isolates, and synergistic in a single isolate. Time-kill analysis on 2 isolates (F/7844 and F/10156), which had synergistic and additive results with amphotericin B, respectively, on checkerboard was performed with 4–16 μg/mL of Mycograb®, 2–8 μg/mL of fluconazole, and 0.0625–2 μg/mL of amphotericin B. This demonstrated an increasingly static effect with augmenting concentrations of fluconazole and an initial static effect with amphotericin B at lower concentrations, which became fungicidal as the level of drug increased. The addition of either 4 or 8 μg/mL of Mycograb® to 0.5 μg/mL of amphotericin B with C. neoformans F/7844 changed a static effect to a fungicidal effect at 8 h with an increased killing of 1.2 logs at 48 h. With C. neoformans F/10156, the addition of 16 μg/mL of Mycograb® to 0.25 μg/mL of amphotericin B produced a difference in killing from 1 logarithm after 4 h to 1.5 logarithms after 48 h. These data suggest that the combination of amphotericin B and Mycograb® would be worth exploring in the treatment of infection due to C. neoformans.

Antifungal effect of various essential oils against Candidaalbicans. Potentiation of antifungal action of amphotericin B by essential oil from Thymus vulgaris

The antifungal effect of the essential oil from Satureja montana L., Lavandula angustifolia Mill., Lavandula hybrida Reverchon, Syzygium aromaticum (L.) Merril and Perry, Origanum vulgare L., Rosmarinus officinalis L. and six chemotypes of Thymus vulgaris L. on Candida albicans growth were studied. The most efficiency was obtained with the essential oil from Thymus vulgaris thymol chemotype (MIC 80% = 0.016 microL/mL and Kaff = 296 microL/mL). The presence in the culture medium of essential oil from Thymus vulgaris thymol chemotype (0.01, 0.1, 0.2, 0.3 microg/mL) and amphotericin B involved a decrease of the MIC 80% of amphotericin B. In contrast, the combination of amphotericin B and low concentrations (0.00031-0.0025 microg/mL) of essential oil was antagonistic. The strongest decrease (48%) of the MIC 80% was obtained with medium containing 0.2 microL/mL of essential oil. These results signify that the essential oil of Thymus vulgaris thymol chemotype potentiates the antifungal action of amphotericin B suggesting a possible utilization of this essential oil in addition to antifungal drugs for the treatment of mycoses.

Regulation of Fungal Infection by a Combination of Amphotericin B and Peptide 2, a Lactoferrin Peptide That Activates Neutrophils

To establish a novel strategy for the control of fungal infection, we examined the antifungal and neutrophil-activating activities of antimicrobial peptides. The duration of survival of 50% of mice injected with a lethal dose of Candida albicans (5 x 10(8) cells) or Aspergillus fumigatus (1 x 10(8) cells) was prolonged 3 to 5 days by the injection of 10 microg of peptide 2 (a lactoferrin peptide) and 10 microg of alpha-defensin 1 for five consecutive days and was prolonged 5 to 13 days by the injection of 0.1 microg of granulocyte-monocyte colony-stimulating factor (GM-CSF) and 0.5 microg of amphotericin B. When mice received a combined injection of peptide 2 (10 microg/day) with amphotericin B (0.5 microg/day) for 5 days after the lethal fungal inoculation, their survival was greatly prolonged and some mice continued to live for more than 5 weeks, although the effective doses of peptide 2 for 50 and 100% suppression of Candida or Aspergillus colony formation were about one-third and one-half those of amphotericin B, respectively. In vitro, peptide 2 as well as GM-CSF increased the Candida and Aspergillus killing activities of neutrophils, but peptides such as alpha-defensin 1, beta-defensin 2, and histatin 5 did not upregulate the killing activity. GM-CSF together with peptide 2 but not other peptides enhanced the production of superoxide (O2-) by neutrophils. The upregulation by peptide 2 was confirmed by the activation of the O2- -generating pathway, i.e., activation of large-molecule guanine binding protein, phosphatidyl-inositol 3-kinase, protein kinase C, and p47phox as well as p67phox. In conclusion, different from natural antimicrobial peptides, peptide 2 has a potent neutrophil-activating effect which could be advantageous for its clinical use in combination with antifungal drugs.

Combination Therapy for Invasive Mycoses: Evaluation of Past Clinical Trial Designs

Despite the availability of new antifungals, single-agent therapy frequently falls short of high cure rates. Combination therapy offers potentially higher cure rates, especially for resistant organisms. In vitro studies and experimental animal models have provided conflicting data. Retrospective, randomized, controlled clinical studies were reviewed. Results indicate a clear advantage for polyene and flucytosine combination therapy in cryptococcal meningitis and a possible advantage for combination amphotericin B and fluconazole for candidemia. Unfortunately, the few studies published have been flawed by design problems that have compromised the determination of outcome. Study review allows investigators the opportunity to design future studies to ensure optimal evaluation of efficacy. Combination antifungal therapy is advantageous in cryptococcal diseases and may have a role in the treatment of invasive candidiasis. The greatest potential exists for combination therapy against aspergillosis and resistant fungi in patients with refractory mycotic disease who experience failure of monotherapy.

Amphotericin B nephrotoxicity in children.

Amphotericin B is the treatment of choice for severe systemic fungal infections. Nephrotoxicity is the most clinically significant adverse effect, but studies examining nephrotoxicity in children are scarce. Nephrotoxicity includes decreased glomerular filtration rate and distal tubulopathy with urinary loss of potassium and magnesium, renal tubular acidosis, loss of urine concentrating ability, and sometimes Fanconi's syndrome. The mechanisms involved in nephrotoxicity include the use of deoxycholate, the vehicle for amphotericin, reduction in renal blood flow and glomerular filtration rate, increased salt concentrations at the macula densa, interaction of amphotericin with ergosterol in the cell membrane, and apoptosis in proximal tubular cells and medullary interstitial cells. Some risk factors for amphotericin nephrotoxicity have been determined over the years. Cumulative dosage, treatment duration, and dosing schedule as well as the combination of amphotericin with other nephrotoxic drugs, such as diuretics and cyclosporine, are important risk factors. Mechanisms to prevent nephrotoxicity include the use of lipid formulations such as amphotericin B lipid complex, amphotericin B colloidal dispersion, and liposomal amphotericin B and the concurrent use of volume repletion. Amiloride can be considered in serious potassium loss.

Successful treatment of a primary cutaneous zygomycosis caused by Absidia corymbifera in a premature newborn.

Mucormycosis (zygomycosis) normally occurs among individuals with predisposing factors such as prematurity, use of broad spectrum antibiotics, metabolic acidosis or advanced stages of immunosuppression. There have been reports of sporadic cases of cutaneous mucormycosis related to predisposing skin lesions and contact with contaminated material such as adhesive bandages and tongue depressors placed close to intravenous catheter insertion sites. We report successful treatment of a case of Absidia corymbifera infection with the combination of amphotericin B and surgical debridement of the affected area.

Primary Central Nervous System Phaeohyphomycosis: A Review of 101 Cases

Phaeohyphomycosis refers to infections caused by darkly pigmented fungi. These fungi rarely cause life-threatening disease. We reviewed 101 cases of culture-proven primary central nervous system phaeohyphomycosis reported in the English-language literature from 1966 to 2002. The most frequently isolated species was Cladophialophora bantiana. The next most frequent isolate was Ramichloridium mackenziei, seen exclusively in patients from the Middle East. More than one-half of the cases occurred in patients with no known underlying immunodeficiency. Mortality rates were high regardless of immune status. Therapy is not standardized, although the combination of amphotericin B, flucytosine, and itraconazole may improve survival rates. Newer azoles, such as voriconazole, also have a broad spectrum of activity against these fungi, although clinical experience is limited. Complete excision of brain lesions may provide better results than simple aspiration. An aggressive medical and surgical approach is warranted in treating these infections to optimize outcomes.

Amphotericin B lipid complex for the treatment of invasive fungal infections

Amphotericin B lipid complex (ABLC; Abelcet®, Enzon Pharmaceuticals) has become the dominant marketed lipid amphotericin B compound to emerge since the approval of these agents from the mid-1990s onwards. This agent is a 1:1 combination of amphotericin B and a lipid moiety consisting of dimyristoyl phosphatidylcholine and dimyrisoyl phosphatidylcholine, which exists in a ribbon-like molecular structure. ABLC undergoes rapid reticuloendothelial uptake from the circulation and achieves significantly higher tissue concentrations in the liver, spleen and lung compared to comparably dosed conventional amphotericin B. ABLC is approved by the FDA for all mycoses in amphotericin B-intolerant or -refractory infection. Randomised, controlled trials of amphotericin B have shown comparable efficacy in candidiasis and an improved outcome in invasive aspergillosis versus historical controls. ABLC has demonstrated a reduced incidence of nephrotoxicity and infusion reactions versus amphotericin B. Comparative studies against other lipid formulations are quite limited and have shown variable differences in infusion toxicity, nephrotoxicity, hepatotoxicity and clinical efficacy. Postapproval experience has shown substantial efficacy for less common mycotic pathogens including zygomycosis. The precise position of ABLC versus both other lipid formulations and expanding formulary of new antifungal agents is in flux. Future studies which examine its clinical efficacy, role in combination therapy, toxicity and cost-effectiveness in these complex patients are needed.

CASPOFUNGIN IN THE TREATMENT OF OROPHARYNGEAL CANDIDIASIS

SUMMARYA patient with AIDS developed oropharyngeal candidiasis. Candida albicans and C. glabrata were isolated from the patient and found to be resistant to fluconazole and itraconazole in vitro. Voriconazole therapy was initiated, but discontinued when the C. albicans strain isolated from the patient was found to be resistant to it. The patient failed to respond to subsequent therapy with a combination of amphotericin B and 5‐flucytosine. Therapy with caspofungin was then initiated (70 mg loading dose, followed by 50 mg/day). The patient responded favourably to caspofungin, with complete resolution of signs and symptoms.

Fusariosis diseminada en paciente con leucemia mieloblástica aguda

Members of the Fusarium genus are ubiquitous soil fungi and are common plant pathogens. More recently, they have become important as pathogens of immunocompromised human patients.A 62-year-old man with acute mielogenous leukemia due to mielodisplastic syndrome treated with chemotherapy, antibiotherapy and amphotericin B developed fever, malaise and red papular skin lesions, asymmetrically distributed over the face, trunk and extremities. Central necrosis appeared in some of them. Laboratory test only revealed anemia, trombopenia and leukopenia. A radiological examination revealed lung inolvement. Skin biopsy showed numerous septate hyphae in mid and deep dermis. A sparse inflammatory infiltrate was present. Culture from skin lesions showed a Fusarium species. Antifungal treatment with a combination of amphotericin B was given without improvement. The skin lesions disappeared with granulocyte colony-stimulating factor therapy and neutropenia recovery.

Antifungal therapy for central nervous system histoplasmosis, using a newly developed intracranial model of infection.

The outcome of central nervous system (CNS) histoplasmosis is often unfavorable. Although fluconazole plays an integral role in treatment of fungal meningitis, its role in the treatment of histoplasmosis is hampered by reduced activity and potential development of resistance. A murine model of CNS histoplasmosis was used to evaluate the hypothesis that a combination of amphotericin B and fluconazole therapy would be superior to amphotericin B monotherapy. Groups of B6C3F(1) mice were infected by injection of Histoplasma capsulatum into the subarachnoid space. The addition of fluconazole hindered the antifungal effect of amphotericin B, as determined by measurement of fungal burden, suggesting antagonism in the brain. Fluconazole was less effective as a single agent than was amphotericin B, despite the greater penetration of fluconazole into brain tissues. The hypothesis that amphotericin B-fluconazole combination therapy would be superior to amphotericin B monotherapy for treatment of CNS histoplasmosis was not supported by this study.