Therapy for fungal infections

Coccidioidomycosis in Persons Infected with HIV Type 1

Coccidioidomycosis is a recognized opportunistic infection among persons infected with human immunodeficiency virus (HIV). Early in the HIV epidemic, most cases presented as overwhelming diffuse pulmonary disease with a high mortality rate. Although these cases are still seen, patients without significant immunodeficiency frequently present with a community-acquired pneumonia syndrome. Diagnosis can be established by cytological staining, culture, or serologic testing. All patients with HIV infection and symptomatic coccidioidomycosis should be treated with antifungal therapy. Severe cases frequently require a combination of therapy with amphotericin B and a triazole antifungal. Therapy for at least 1 year is recommended, but for patients with a focal pulmonary infection and peripheral blood CD4 lymphocyte counts of >250 cells/microL, it may be reasonable to stop therapy after this time. Other manifestations of coccidioidomycosis require prolonged therapy, and life-long treatment is recommended for persons with meningitis.

Molecular modelling of amphotericin B-ergosterol primary complex in water

The properties of amphotericin B-ergosterol primary complex have been studied with the use of the molecular dynamics simulation. Possible geometries of the complex were tested first in order to find the structures with the most favourable values of the intermolecular interactions energy. The molecules studied possessed a tendency to fit each other's shapes, which favours intermolecular van der Waals interactions. The main simulations were performed for the best structures found. Presence of hydrogen bonds between the sterol hydroxyl group and polar fragments of mycosamine (most frequently 2'OH) was coupled with a relatively high level of the intermolecular energy values. The structures obtained are hardly comparable to the hypothetical and 'computational' models of the antibiotic-sterol complex. The geometries found are not suitable to assemble the presupposed structure of the water channel, however, the existence of the complex in the shape anticipated is not in contradiction to the results of biophysical experiments on the complexation in water and in hydroalcoholic media.

MR imaging of cavernous sinus invasion by mucormycosis: a case study

Cavernous sinus thrombosis is a serious condition, which, if not recognized early, can lead to a fulminant course. Knowledge of risk factors along with early recognition of signs and symptoms may alter the course of this condition. We present a case of a patient with cavernous sinus thrombosis with characteristic findings on MRI. Biopsy of the sinuses revealed mucromycosis as the offending agent.

Conformational properties of amphotericin B amide derivatives--impact on selective toxicity

Even though it is highly toxic, Amphotericin B (AmB), an amphipathic polyene macrolide antibiotic, is used in the treatment of severe systemic fungal infections as a life-saving drug. To examine the influence of conformational factors on selective toxicity of these compounds, we have investigated the conformational properties of five AmB amide derivatives. It was found that the extended conformation with torsional angles (phi,psi)=(290 degrees,180 degrees) is a common minimum of the potential energy surfaces (PES) of unsubstituted AmB and its amide derivatives. The extended conformation of the studied compounds allows for the formation of an intermolecular hydrogen bond network between adjacent antibiotic molecules in the open channel configuration. Therefore, the extended conformation is expected to be the dominant conformer in an open AmB (or its amide derivatives) membrane channel. The derivative compounds for calculations were chosen according to their selective toxicity compared to AmB and they had a wide range of selective toxicity. Except for two AmB derivatives, the PES maps of the derivatives reveal that the molecules can coexist in more than one conformer. Taking into account the cumulative conclusions drawn from the earlier MD simulation studies of AmB membrane channel, the results of the potential energy surface maps, and the physical considerations of the molecular structures, we hypothesize a new model of structure-selective toxicity of AmB derivatives. In this proposed model the presence of the extended conformation as the only well defined global conformer for AmB derivatives is taken as the indicator of their higher selective toxicity. This model successfully explains our results. To further test our model, we also investigated an AmB derivative whose selective toxicity has not been experimentally measured before. Our prediction for the selective toxicity of this compound can be tested in experiments to validate or invalidate the proposed model.

Meningoencephalitis due to Blastomyces dermatitidis: case report and literature review

Infection of the central nervous system by Blastomyces dermatitidis is a rare cause of meningoencephalitis. The existence of exclusive clinical infection of the meninges in the absence of pulmonary or other foci of infection has been debated. We describe a 20-year-old man presenting with meningoencephalitis caused by B dermatitidis. Blastomycotic infection was confirmed by isolation of the organism from brain tissue obtained at biopsy. Magnetic resonance imaging demonstrated progressive enhancement of basal meninges with involvement of bilateral basal ganglia and thalami. Treatment with amphotericin B arrested further neurologic decline. However, clinical and radiographic follow-up suggested damage to diencephalic structures. The diagnosis of blastomycotic meningoencephalitis is difficult to establish because no sensitive serologic test exists, and attempts to isolate the organism in cerebrospinal fluid obtained by lumbar puncture generally fail. A biopsy specimen of brain tissue is frequently necessary for the diagnosis. Survival is possible with timely initiation of therapy.

[Systemic paracoccidioidomycosis with central nervous system involvement]

A clinical case of a patient bearing systemic paracoccidioidomycosis with regional ganglionic and oral exposure and later pulmonary involvement is presented. The patient was treated with specific drugs (amphotericin B, itraconazole, sulfamethoxazole-trimethoprim) and followed throughout a 6-year period and eventually died showing an extensive involvement of the central nervous system.

Pulmonary aspergillosis and invasive disease in AIDS: review of 342 cases

Aspergillosis is an infrequent but commonly fatal infection among HIV-infected individuals. We review 342 cases of pulmonary Aspergillus infection that have been reported among HIV-infected patients, with a focus on invasive disease. Invasive pulmonary aspergillosis usually occurs among patients with <50 CD4 cells/mm3. Major predisposing conditions include neutropenia and steroid treatment. Fever, cough, and dyspnea are each present in >60% of the cases. BAL is often suggestive, but biopsy specimens are necessary for definite diagnosis. Amphotericin B is the mainstay of treatment and mortality is > 80%. Avoiding neutropenia and judicious use of steroids may be helpful in prevention. Aggressive diagnostic approach, early initiation of treatment, adequate dosing of antifungals, and close follow-up may improve the currently dismal prognosis.

[High-dose therapy with fluconazole > or = 800 mg/day. Review]

The clinical use of fluconazole in dosages > or = 800 mg/day has been reported in about 900 patients against candidemia, oropharyngeal candidiasis and cryptococcal meningitis in HIV-infected patients as well as for initial therapy of endemic mycoses. Especially in patients with life-threatening infections caused by Candida spp., Cryptococcus neoformans and Coccidioides immitis, the results of a limited number of dose-finding trials with non-neutropenic and HIV-infected patients show dose-dependent response rates. These findings strongly advocate the application of high dose-fluconazole; their evaluation, however, still awaits final clarification. The good safety profile for dosages up to 2000 mg/day and the linear, predictable pharmacokinetics up to 1600 mg/day indicate the excellent tolerability of fluconazole in the clinical situation which justifies prospective, randomized clinical trials with treatment groups as homogeneous as possible for further evaluation of the optimum dosage and duration of treatment.

High-dose therapy with fluconazole > or = 800 mg day-1

Fluconazole dosages greater than 800 mg day-1 have been reported in about 900 patients treated for candidemia, oropharyngeal candidiasis and cryptococcal meningitis in HIV-infected patients, and for initial therapy of endemic mycoses. In patients with life-threatening infections caused by Candida spp., Cryptococcus neoformans and Coccidioides immitis, results of a limited number of dose-finding trials with non-neutropenic and HIV-infected patients show dose-dependent responses. These study results indicate that higher daily doses of fluconazole than are currently approved for these indications are well tolerated and tend to provide better clinical efficacy in selected patient populations. An excellent safety profile of dosages up to 2000 mg day-1 and linear predictable pharmacokinetics up to 1600 mg day-1 appear to justify further clinical investigations to better determine the optimum dosage and duration of treatment.

Clinical pharmacokinetics of fluconazole in superficial and systemic mycoses

The bis triazole agent fluconazole is used widely in the treatment of superficial and deep mycoses. A single oral dose of fluconazole 150 mg gives a mean long term clinical cure rate of 84 +/- 5% and is considered a valuable alternative to other topical antifungal drugs for vaginal candidiasis. A clinical cure rate of 90.4% for oropharyngeal candidiasis was obtained with 100mg daily for a minimum of 14 days; however, as for the other azoles the rate of relapse was large (40%) in immunocompromised patients. A daily dose of 100mg for at last 3 weeks gave satisfying outcomes for oesophageal candidiasis. Most patients (71 to 86%) with signs and symptoms of urinary tract candidiasis show beneficial clinical results when given oral fluconazole 50mg for several weeks. Fluconazole 50 to 150 mg given for weeks or months results in over 90% clinical cure or improvement for cutaneous mycosis including tinea, pityriasis, cryptococcosis and candidiasis. Prolonged (6 to 12 months) fluconazole 150 mg once a week is needed to treat onychomycosis successfully. Higher oral doses (200 to 400 mg daily) for long periods are generally used to treat deep mycoses such as meningitis, ophthalmitis, pneumonia, hepatosplenic mycosis and endocarditis. Fluconazole is effective for treating the fungal peritonitis which can complicate continuous ambulatory peritoneal dialysis (CAPD). A regimen of 50 mg intraperitoneally or 100 mg orally was used in these patients with impaired renal function. The dosage schedules used to treat disseminated fungal infections due to systemic mycoses with different or multiple foci of infections vary widely, with doses of 50 to 400 mg given orally or intravenously for between 1 week and several months. The most recent clinical reports have investigated the use of prophylaxis with fluconazole 100 to 400 mg daily, in immunocompromised patients. Fluconazole is found in body fluids such as vaginal secretions, breast milk, saliva, sputum and cerebrospinal fluid at concentrations comparable with those determined in blood after single or multiple doses. There is an excellent linear plasma concentration-dose relationship, but the mycological and clinical responses do not appear to be well correlated with the dose. A total maximum daily dose of 1600 mg is recommended to avoid neurological toxicity. Data from pharmacokinetic studies conducted in patients, mainly those with AIDS, and using a 1-compartment model give very constant parameters similar to those obtained in healthy individuals. Bioavailability, measured in HIV-positive patients and those with AIDS, exceeded 93% for tablets, suspension and suppositories. The time to reach peak plasma concentrations (tmax) was 2.4 to 3.7 hours. The peak plasma drug concentration (Cmax) obtained after a 100 mg oral dose was 2 mg/L. Areas under the concentration-time curve (AUC) obtained in different studies all correlate well with the dose (r = 0.926). The AUC determined after 200 and 25 mg suppositories were similarly well correlated. Hypochlorhydria does not affect the absorption of fluconazole, neither does food intake, race (Japanese or Caucasian) or gastrointestinal resection. Binding to plasma protein is low (11.14%) and is increased to 23% in cancer patients. Fluconazole is rapidly distributed to the tissue, where it accumulates. Tissues fall into 1 of 4 groups of increasing drug concentration: blood, bone and brain have the lowest concentrations, and spleen has the highest. The volume of distribution (Vd) remains stable at 46.3 +/- 7.9L and is considered to be an 'invariant' parameter across species. Fluconazole is poorly metabolised and is mainly eliminated unchanged in the urine. The percentage of the dose recovered in the urine in 48 hours is close to 60%. Concentrations in the urine are high and the half-life (t1/2) is long (37.2 +/- 5.5h) in patients, mainly those with AIDS, which is not significantly different from the t1/2 (31.4 +/- 4.7 hours) in healthy individuals. (ABSTRACT TRUN

Patient selection, evaluation, and preoperative management for lung transplant candidates

The selection process to assess candidacy for transplant is based on medical and psychosocial criteria and surgical considerations. The degree of disease severity requiring transplantation for survival has become more apparent as the disparity in survival outcome widens between patients with and without transplant. The contraindications to transplant surgery have been modified over time. Candidate selection is considered in the context of the risks and benefits of the surgical procedure on a case by case basis. The wait for transplant has increased as the growth in the number of candidates for transplant exceeds available donors. As much as 30% of patients die on the UNOS waiting list.

The deep mycoses in HIV infection

The deep mycoses are uncommon infections, usually acquired from the inhalation or ingestion of fungal spores, sometimes from the soil in areas of endemicity, such as in the Americas and south-east Asia, or from decaying vegetable matter. They are also seen in immunocompromised persons and, increasingly, in HIV-infected persons. Respiratory involvement is frequent, with granuloma formation, and mucocutaneous involvement may be seen. Oral lesions of the deep mycoses are typically chronic but non-specific, though nodular or ulcerative appearances are common. Person-to-person transmission is rare. In HIV disease, the most common orofacial involvement of deep mycoses has been in histoplasmosis, cryptococcosis, aspergillosis and zygomycosis. Diagnosis is usually confirmed by lesional biopsy although culture may also be valuable. Treatment is with amphotericin or an azole.

Blastomycosis of the eyelid

BACKGROUND

Published reports indicate that eyelid involvement occurs in approximately 25% of patients with systemic blastomycosis and that mortality exceeds 60% in untreated patients. The purpose of this study is to investigate this purportedly frequent association.

METHODS

The Medical Diagnostic index of the Mayo Clinic was used to identify patients who were treated for blastomycosis from 1976 through 1993. The medical records of affected patients were reviewed.

RESULTS

Of 79 patients with blastomycosis, only 1 (1.27%; 95% confidence interval, 0.03%-6.85%) had eyelid involvement. The diagnosis of systemic disease was established in this patient after biopsy of the eyelid lesion, and the infection responded satisfactorily to treatment with itraconazole.

CONCLUSION

Contrary to previous reports, eyelid involvement with systemic blastomycosis is uncommon.