Fluconazole and ketoconazole in the treatment of oral and esophageal candidiasis in AIDS patients

Management of oropharyngeal and esophageal candidiasis in patients with HIV infection

Mucocutaneous candidiasis is frequently one of the first signs of HIV infection. Over 90% of patients with AIDS will develop oropharyngeal candidiasis at some time during their illness. Although numerous antifungal agents have been developed, azoles, both topical (clotrimazole) and systemic (fluconazole, itraconazole, voriconazole and posaconazole), have replaced older topical antifungals (gentian violet and nystatin) in the management of oropharyngeal candidiasis in these patients. The systemic azoles are generally safe and effective agents in HIV-infected patients with oropharyngeal candidiasis. A constant concern in these patients are relapses, which depend on the degree of immunosuppression and are commonly encountered after topical therapy rather than with systemic azole therapy. In patients with fluconazole-refractory mucosal candidiasis, treatment options now include itraconazole solution, voriconazole, posaconazole and the newer echinocandins (caspofungin, micafungin and anidulafungin). The objective of this article is to review the epidemiology, diagnosis and newer management modalities of oropharyngeal and esophageal candidiasis in HIV-infected individuals.

Optimal management of oropharyngeal and esophageal candidiasis in patients living with HIV infection

Mucocutaneous candidiasis is frequently one of the first signs of human immunodeficiency virus (HIV) infection. Over 90% of patients with AIDS will develop oropharyngeal candidiasis (OPC) at some time during their illness. Although numerous antifungal agents are available, azoles, both topical (clotrimazole) and systemic (fluconazole, itraconazole, voriconazole, posaconazole) have replaced older topical antifungals (gentian violet and nystatin) in the management of oropharyngeal candidiasis in these patients. The systemic azoles, are generally safe and effective agents in HIV-infected patients with oropharyngeal candidiasis. A constant concern in these patients is relapse, which is dependent on the degree of immunosuppression commonly seen after topical therapy, rather than with systemic azole therapy. Candida esophagitis (CE) is also an important concern since it occurs in more than 10% of patients with AIDS and can lead to a decrease in oral intake and associated weight loss. Fluconazole has become the most widely used antifungal in the management of mucosal candidiasis. However, itraconazole and posaconazole have similar clinical response rates as fluconazole and are also effective alternative agents. In patients with fluconazole-refractory mucosal candidiasis, treatment options now include itraconazole solution, voriconazole, posaconazole, and the newer echinocandins (caspofungin, micafungin, and anidulafungin).

Fungal ball of the oesophagus

Candidal colonization of the gastrointestinal tract is common, but localized complications are rare. A case of an oesophageal fungal ball is described.

Emergence of resistance of Candida albicans to clotrimazole in human immunodeficiency virus-infected children: in vitro and clinical correlations

Oropharyngeal candidiasis (OPC) is a common opportunistic infection in human immunodeficiency virus (HIV)-infected patients and other immunocompromised hosts. Clotrimazole troches are widely used in the treatment of mucosal candidiasis. However, little is known about the potential contribution of clotrimazole resistance to the development of refractory mucosal candidiasis. We therefore investigated the potential emergence of resistance to clotrimazole in a prospectively monitored HIV-infected pediatric population receiving this azole. Adapting the National Committee for Clinical Laboratory Standards M27-A reference method for broth antifungal susceptibility testing of yeasts to clotrimazole, we compared MICs in macrodilution and microdilution assays. We further analyzed the correlation between these in vitro findings and the clinical response to antifungal therapy. One isolate from each of 87 HIV-infected children was studied by the macrodilution and microdilution methods. Two inoculum sizes were tested by the macrodilution method (10(3) and 10(4) CFU/ml) in order to assess the effect of inoculum size on clotrimazole MICs. The same isolates also were tested using a noncolorimetric microdilution method. Clotrimazole concentrations ranged from 0.03 to 16 microg/ml. Readings were performed after incubation for 24 and 48 h at 35 degrees C. For 62 (71.2%) of 87 clinical isolates, the MICs were low (< or =0.06 microg/ml). The MIC for 90% of the strains tested was 0.5 microg/ml, and the highest MIC was 8 microg/ml. There was no significant difference between MICs at the two inoculum sizes. There was 89% agreement (+/-1 tube) between the microdilution method at 24 h and the macrodilution method at 48 h. If the MIC of clotrimazole for an isolate of C. albicans was > or =0.5 microg/ml, there was a significant risk (P < 0.001) of cross-resistance to other azoles: fluconazole, > or = 8 microg/ml (relative risk [RR] = 8.9); itraconazole, > or =1 microg/ml (RR = 10). Resistance to clotrimazole was highly associated with clinically overt failure of antifungal azole therapy. Six (40%) of 15 patients for whom the clotrimazole MIC was > or =0.5 microg/ml required amphotericin B for refractory mucosal candidiasis versus 4 (5.5%) of 72 for whom the MIC was <0.5 microg/ml (P = 0.001; 95% confidence interval = 2.3 to 22; RR = 7.2). These findings suggest that an interpretive breakpoint of 0.5 microg/ml may be useful in defining clotrimazole resistance in C. albicans. The clinical laboratory's ability to determine MICs of clotrimazole may help to distinguish microbiologic resistance from the other causes of refractory OPC, possibly reducing the usage of systemic antifungal agents. We conclude that resistance to clotrimazole develops in isolates of C. albicans from HIV-infected children, that cross-resistance to other azoles may develop concomitantly, and that this resistance correlates with refractory mucosal candidiasis.

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

Susceptibility testing of fungi: current status of correlation of in vitro data with clinical outcome

In summary, it is clear that in vitro susceptibility testing can predict outcome in selected clinical situations. The clearest data are from the fluconazole-treated AIDS patients with oropharyngeal candidiasis. In this setting, the homogeneity of the underlying immune defect, combined with the ease of identification and monitoring of the infection, creates a near-perfect test situation. In more complex scenarios, such as the heterogeneous population of patients enrolled in a recent study of candidemia, no such clear-cut correlation was present. The importance of host factors in the correlation of the MIC with outcome cannot be overemphasized. Examples of these parameters include patient status (underlying disease, the presence of intravascular catheters, and CD4+ T-cell number), drug pharmacokinetics (absorption and distribution), patient compliance, and drug-drug interactions. Identification of relevant factors can substantially improve the degree of the MIC-outcome correlation and thus improve the clinical utility of in vitro testing. An important feature in this entire process is the role of standardized susceptibility testing procedures. While not without flaws, the proposed NCCLS reference method has been invaluable in allowing multiple investigators to contribute data that can be used to clarify the correlation between the fluconazole MIC and outcome. While the development of simplified second-generation methods is eagerly anticipated, the role of the reference method as a common touchstone is critical. Only by use of either the reference method itself or methods with a known relationship to the reference method can this broad collaborative process really proceed. Current work is focusing on defining interpretive breakpoints for fluconazole and Candida species, refinement of the in vitro procedures used to measure susceptibility to amphotericin B, ketoconazole, and itraconazole, and the acquisition of a broad base of data on the relationship between the MIC and outcome for these three drugs. Although considerable work remains to be done, the available data suggest that solutions to each of these problems are possible and that routine susceptibility testing of fungi will become meaningful for clinical decision making in the foreseeable future.

Correlation between in vitro resistance to fluconazole and clinical outcome of oropharyngeal candidiasis in HIV-infected patients

Fifty episodes of oropharyngeal candidiasis in HIV-infected patients were analyzed prospectively in order to evaluate the clinical response to fluconazole. The minimum inhibitory concentrations (MICs) of fluconazole for the Candida strains isolated from the pharynx were correlated with the clinical response. Treatment with fluconazole (100 mg/day) was successful in 86% of the cases. A good clinical outcome followed in 97% of the cases when a strain sensitive to fluconazole was isolated. This figure fell to 22% when the strain was resistant to fluconazole (p < 0.001). The rate of post-treatment colonization was high (87%), and selection of non-albicans Candida species occurred in 23% of the cases. In conclusion, fluconazole treatment for oropharyngeal candidiasis of HIV-infected patients was useful in most cases, but less sensitive non-albicans species can be selected. Most treatment failures were associated with increased MICs of fluconazole for the strains isolated before treatment; therefore, susceptibility testing is recommended as an aid in clinical decision-making for the use of the azole group of drugs.

Oropharyngeal candidiasis in immunocompromised children: a randomized, multicenter study of orally administered fluconazole suspension versus nystatin. The Multicenter Fluconazole Study Group

OBJECTIVE

To compare the efficacy, safety, and tolerance of fluconazole suspension versus nystatin in the treatment of oropharyngeal thrush in immunocompromised children.

DESIGN

Multicenter, randomized, observer-masked trial.

SETTING

Thirty-two centers participated, including hospitals and ambulatory care clinics.

PATIENTS

We enrolled 182 immunocompromised infants and children, ages 5 months to 14 years, with signs of oral thrush and presence of yeasts on potassium hydroxide- or gram-stained preparations. Subjects were randomly assigned to receive a single daily dose of fluconazole suspension, 2 to 3 mg/kg per day, or nystatin, 400,000 units four times daily for 14 days; 159 patients, who had culture confirmation of thrush and received at least 7 days of study drug, were evaluated for efficacy; all patients were evaluated for safety.

RESULTS

Clinical cure was demonstrated in 91% of the subjects in the fluconazole group and 51% of the subjects in the nystatin group (p < 0.001), and eradication of the organism cultured at entry occurred in 76% and 11% (p < 0.001), respectively. Gastrointestinal conditions developed in six patients who received fluconazole and in three who received nystatin; two fluconazole recipients were subsequently withdrawn from the study. Laboratory abnormalities occurred with equal frequency in both groups. Clinical relapse rates were similar in both groups at 2 weeks (18% and 24% for fluconazole and nystatin, respectively) and 1 month (28% and 27%, respectively) after the completion of study drug.

CONCLUSIONS

Fluconazole suspension is more effective than nystatin in the treatment of thrush in immunocompromised children. Both regimens were well tolerated.

Treatment of oral candidiasis in HIV infection

Oral candidiasis is one of the most common clinical features of HIV infection. The lesion occurs in three predominant forms, and the two intraoral examples, pseudomembranous and erythematous, are equally predictive of the development of AIDS, independent of CD4 counts. The predominant species is C. albicans, although other species are occasionally found. Some studies claim correlation of salivary Candida counts with CD4 numbers or clinical stage of HIV-related disease, but this approach has not been used widely in HIV staging. Therapy with a variety of antifungal agents, including both topical and systemic drugs, is effective. New slow-release oral topical drug delivery systems may prove to be useful. Recently, examples of resistance to some drugs have been reported. Resistance may be associated with the emergence of different species.

Turbidimetric and visual criteria for determining the in vitro activity of six antifungal agents against Candida spp. and Cryptococcus neoformans

The drug concentration which inhibited 50% of growth (IC50), the lowest drug concentration at which growth was less than 30% of that in a positive control well (IC30), the visual minimal inhibitory concentration (MIC), and the minimum fungicidal concentration (MFC), were applied to study the effects of fluconazole, itraconazole, ketoconazole, miconazole, flucytosine, and amphotericin B against 36 isolates of Candida spp. and Cryptococcus neoformans by a broth microdilution technique. When the recommendations established by the NCCLS Subcommittee on Antifungal Susceptibility Tests were applied for the visual reading of the microplates, the results were comparable with those obtained by the turbidimetric methods. Differences between MICs and IC30s were observed with miconazole against strains of C. glabrata (p = 0.014) and with flucytosine against strains of C. neoformans (p = 0.041). Differences between MICs and IC50s were observed with fluconazole against strains of C. albicans (p = 0.027), C. tropicalis (p = 0.046), and C. neoformans (p = 0.041); with miconazole against strains of C. glabrata (p = 0.014); and with amphotericin B against strains of C. parapsilosis (p = 0.025). Ten additional isolates of C. albicans from AIDS patients suffering from recurrent episodes of oral candidiasis and clinically resistant to fluconazole also were included in this study. The MICs of fluconazole of these strains were significantly higher than those of the control group (p = 0.003). When the turbidimetric parameters were applied for testing the in vitro activity of fluconazole against the above isolates, both IC30 and IC50 were capable of discriminating the strains of the two groups (p = 0.002, p = 0.001, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)