Clinically significant mucosal candidiasis resistant to fluconazole treatment in patients with AIDS

Interventions for prevention and treatment of vulvovaginal candidiasis in women with HIV infection

BACKGROUND

Vulvovaginal candidiasis (VVC) is one of the most common fungal infections that recur frequently in HIV infected women. Symptoms of VVC are pruritis, discomfort, dyspareunia, and dysuria. Vulval infection presents as a morbiliform rash that may extend to the thighs. Vaginal infection is associated with white discharge, and plaques are seen on erythematous vaginal walls.Even though rarely or never resulting in systemic fungal infection or mortality, left untreated these lesions contribute considerably to the morbidity associated with HIV infection. Prevention and treatment of this condition is an essential part of maintaining the quality of life for these individuals.

OBJECTIVES

-To compare the efficacy of various antifungals given vaginally or orally for the treatment and prophylaxis of VVC in HIV-infected women and to evaluate the risks of the same.

SEARCH STRATEGY

The search strategy was comprehensive, iterative and based on that of the HIV/AIDS Cochrane Review Group. The aim was to locate all relevant trials, irrespective of publication status or language. Electronic databases :CENTRAL,Medline, EMBASE, LILACS and CINAHL were searched for randomised controlled trials for the years 1980 to 1st October 2010. WHO ICTRP site and other relevant web sites were also searched for conference abstracts.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of palliative, preventative or curative therapy were considered. Participants were HIV positive women receiving one or more of the following:treatment / prophylaxis for VVC or HAART(Highly Active Antiretroviral Therapy).

DATA COLLECTION AND ANALYSIS

Three authors independently assessed the methodological quality of the trials and extracted data. The quality of the evidence generated was graded using the GRADE PRO approach.

MAIN RESULTS

Our search did not yield any trial investigating treatment of VVC in HIV positive women.Two trials dealing with prophylaxis were eligible for inclusion.One trial (n= 323) favoured the use of weekly Fluconazole as compared to placebo (RR 0.68; 95% CI 0.47 to 0.97).The second trial with three arms of comparison;Clotrimazole,Lactobacillus and Placebo gave no definitive results in preventing an episode of VVC. Clotrimazole against placebo (RR 0.49; 95% CI 0.22 to 1.09), Clotrimazole against lactobacillus (RR 1.11; 95% CI 0.45 to 2.76) and lactobacillus against placebo (RR 0.54 ;95% CI 0.26 to 1.13).

AUTHORS' CONCLUSIONS

Implications for practiceNo trials were found addressing treatment of VVC in HIV positive women.In comparison to placebo,Fluconazole was found to be an effective preventative intervention. However, the potential for resistant Candida organisms to develop might impact the feasibility of implementation.Direction of findings suggests that Clotrimazole and Lactobacillus improved the prophylactic outcomes when compared to placebo.Implications for research There is a need to evaluate drugs and drug regimens for VVC treatment and prophylaxis in HIV positive women through randomised clinical trials. Development of resistance to azoles remains under-studied and more work must be done in this area, so as to determine whether routine prophylaxis for VVC is at all needed or whether adequate ART would be sufficient to prevent recurrent VVC. The viral load in vaginal secretions with or without treatment or prophylaxis has not been studied, this is very relevant to the spread of HIV.

Epidemiology of mycoses in the HIV-infected patient: clinical aspects

Among the major problems confronting patients with AIDS are opportunistic fungal infections. Primary infections include candidiasis, cryptococcosis, the major endemic mycoses, and aspergillosis. The endemic mycoses of AIDS consist of Histoplasma found mostly in the U.S. and Latin America, Coccidioides in parts of Latin America and the southwest U.S., Penicillium marneffei in Thailand and other parts of southeast Asia, and Blastomyces worldwide. The latter, however, has so far been rare in AIDS. The major endemic mycoses tend to target patients very late in AIDS, with CD4 counts commonly below 100. Diagnosis is usually made by characteristic morphology of the fungal elements as seen at microscopy, and the pathogens are readily cultured from infected tissues, and in the case of Histoplasma, from blood.

Photodynamic therapy of bacterial and fungal biofilm infections

Biofilms have been found to be involved in a wide variety of microbial infections in the body, by one estimate 80% of all infections. Infectious processes in which biofilms have been implicated include common problems such as urinary tract infections, catheter infections, middle-ear infections, sinusitis, formation of dental plaque, gingivitis, coating contact lenses, endocarditis, infections in cystic fibrosis, and infections of permanent indwelling devices such as joint prostheses and heart valves. Bacteria living in a biofilm usually have significantly different properties from free-floating bacteria of the same species, as the dense and protected environment of the film allows them to cooperate and interact in various ways. One benefit of this environment is increased resistance to detergents and antibiotics, as the dense extracellular matrix and the outer layer of cells protect the interior of the community. In some cases antibiotic resistance can be increased 1000-fold. Also, the biofilm bacteria excrete toxins that reversibly block important processes such as translation and protecting the cell from bactericidal antibiotics that are ineffective against inactive targets. In the head and neck area, biofilms are a major etiologic factor in periodontitis, wound infections, oral candidiasis, and sinus and ear infections. For the past several decades, photodynamic treatment has been reported in the literature to be effective in eradicating various microorganisms using different photosensitizers, different wavelengths of light, and different light sources. PDT has been further studied to demonstrate its effectiveness for the eradication of both Gram-negative and Gram-positive antibiotic-resistant bacteria. This chapter will focus on the use of PDT in the treatment of antibiotic-resistant biofilms, antibiotic-resistant wound infections, and azole-resistant oral candidiasis using methylene blue-based photodynamic therapy.

Rapid identification of Candida species in oral rinse solutions by PCR

AIMS

To determine the sensitivity and specificity of a multiplex PCR assay for the contemporary identification of major species involved in oral candidiasis, without extraction and purification of DNA from the samples under investigation; and evaluation of this method in comparison with routine phenotypic culture identification.

METHODS

78 oral rinse solutions were collected. The concentrated oral rinse technique was used for a quantitative and qualitative study. Research and identification of Candida spp, with routine phenotypic culture identification (germ-tube test in serum at 37 degrees C for 3 hours and sugar assimilation strip analysis), were performed. Each sample was analysed with multiplex PCR directly on oral rinse solution. Samples giving discrepant results between routine phenotypic and PCR identification methods were resubcultured on CHROMagar Candida plates. The fungus-specific primers ITS1, ITS2, CA3, and CA4 were used. For the identification of other species (C kefyr, C famata and C dubliniensis), ITS1F, ITS1K, and ITS2D primers were designed.

RESULTS

Multiplex PCR correctly identified all samples, including those with single species, or with mixed species, negative samples and positive samples which appeared to be negative from routine phenotypic methods.

CONCLUSION

This multiplex PCR assay provides a rapid alternative to the conventional culture based technique for the identification and speciation of the most frequently isolated Candida species. The absence of an extraction method made identification of 10 species possible in a few hours.

Safety and efficacy of posaconazole in the long-term treatment of azole-refractory oropharyngeal and esophageal candidiasis in patients with HIV infection

PURPOSE

To evaluate safety and efficacy of long-term posaconazole in HIV-infected patients with azole-refractory oropharyngeal candidiasis and/or esophageal candidiasis.

METHOD

In this noncomparative, open-label study, participants received oral posaconazole 400 mg twice daily (bid) for 3 months. Enrolled patients (N = 100) included 60 from a previous 1-month acute study of posaconazole and 40 posaconazole-naïve participants. Participants with a clinical response could be followed untreated for up to 1 month afterwards. Participants who relapsed during follow-up, showed improvement at the end of 3 months of treatment (EOT), or were cured but likely to benefit from further therapy could continue on posaconazole 400 mg bid for up to 12 months.

RESULTS

In the modified intent-to-treat population, clinical response (cure or improvement) occurred in 85.6% (77/90) at EOT. The results were similar in the previously treated participants and the posaconazole-naïve participants, 88.1% (52/59) and 80.6% (25/31), respectively. Posaconazole was well-tolerated, showing a similar safety profile during the 3-month study period and during suppressive therapy. The most frequently reported treatment-related adverse event was vomiting (4/100, 4%) during the early follow-up period (on or before day 105) and elevated hepatic enzymes (3/51, 6%) during the long-term follow-up (after day 105).

CONCLUSION

Oral posaconazole 400 mg bid demonstrated long-term safety, tolerability, and efficacy, offering a long-term, suppressive treatment option for HIV-infected participants with azole-refractory mucosal candidiasis.

Pharmacokinetics and pharmacodynamics of antifungals

Application of pharmacodynamic principles to antifungal drug therapy of Candida and Aspergillus infections has provided and understanding of the relationship between drug dosing and treatment efficacy. Observations of the pharmacodynamics of triazoles and AmB have correlated with the results of clinical trials and have proven useful for validation of in vitro susceptibility breakpoints. Although there remain many unanswered questions regarding antifungal pharmacodynamics, available data suggest usefulness in the application of pharmacodynamics to antifungal clinical development. Future application of these principles should aid in the design of optimal combination antifungal therapies.

Biology of the pathogenic yeast Candida glabrata

The yeasts, being favorite eukaryotic microorganisms used in food industry and biotechnologies for production of biomass and various substances, are also used as model organisms in genetic manipulation, molecular and biological research. In this respect, Saccharomyces cerevisiae is the best-known species but current situation in medicine and industry requires the use of other species. Here we summarize the basic taxonomic, morphological, physiological, genetic, etc. information about the pathogenic yeast Candida glabrata that is evolutionarily very closely related to baker's yeast.

A Multicenter Randomized Trial Evaluating Posaconazole versus Fluconazole for the Treatment of Oropharyngeal Candidiasis in Subjects with HIV/AIDS

BACKGROUND

Oropharyngeal candidiasis is the most common opportunistic infection among persons infected with human immunodeficiency virus (HIV). Use of some agents is hampered by lack of efficacy, emergence of resistance, adverse events, and need for intravenous administration. Posaconazole is an extended-spectrum triazole with potent in vitro activity against Candida species, including Candida albicans, Candida glabrata, and Candida krusei (including fluconazole-resistant strains).

METHODS

This multicenter, randomized, evaluator-blinded study of subjects with HIV infection and oropharyngeal candidiasis compared efficacy of posaconazole with that of fluconazole. Subjects received either 200 mg of posaconazole or fluconazole oral suspension on day 1, followed by 100 mg/day for 13 days. The primary study end point--clinical success (cure or improvement) on day 14--was evaluated for 329 subjects. Durability of clinical success was evaluated on day 42.

RESULTS

Three hundred fifty subjects received posaconazole (n = 178) or fluconazole (n = 172). Clinical success occurred in 155 (91.7%) of 169 posaconazole recipients and in 148 (92.5%) of 160 fluconazole recipients (95% confidence interval, -6.61% to 5.04%), indicating that posaconazole was not inferior to fluconazole. On day 14, mycological success was 68% in both arms, but by day 42, significantly more posaconazole recipients than fluconazole recipients continued to have mycological success (40.6% vs. 26.4%; P=.038). Fewer posaconazole recipients than fluconazole recipients experienced clinical relapse (31.5% vs. 38.2%). Adverse events were similar between treatment arms.

CONCLUSIONS

Results demonstrate that posaconazole was as effective as fluconazole in producing a successful clinical outcome. However, posaconazole was more effective in sustaining clinical success after treatment was stopped.

A randomized study of the use of fluconazole in continuous versus episodic therapy in patients with advanced HIV infection and a history of oropharyngeal candidiasis: AIDS Clinical Trials Group Study 323/Mycoses Study Group Study 40

BACKGROUND

In human immunodeficiency virus (HIV)-infected patients, fluconazole prophylaxis is associated with reductions in the rate of fungal infection. However, concerns exist with regard to the use of fluconazole prophylaxis and the risk of development of fluconazole treatment-refractory infections.

METHODS

We performed a randomized, open-label trial that compared oral fluconazole given continuously (200 mg 3 times weekly; the "continuous fluconazole arm") with fluconazole that was provided only for episodes of orophayngeal candidiasis (OPC) or esophageal candidiasis (EC) (the "episodic fluconazole arm") in HIV-infected persons with CD4+ T cell counts of <150 cells/mm3 and a history of OPC. The primary study end point was the time to development of fluconazole-refractory OPC or EC, which was defined as lack of response to 200 mg fluconazole given daily for 14 or 21 days, respectively.

RESULTS

A total of 413 subjects were randomized to receive continuous fluconazole, and 416 were randomized to receive episodic fluconazole. After 42 months, 17 subjects (4.1%) in the continuous fluconazole arm developed fluconazole-refractory OPC or EC infections, compared with 18 subjects (4.3%) in the episodic fluconazole arm, with no difference between treatment arms with regard to the time to development of a fluconazole-refractory infection within 24 months (P=.88, by log-rank test) or before the end of the study (P=.97, by the log-rank test). Continuous fluconazole therapy was associated with fewer cases of OPC or EC (0.29 vs. 1.08 episodes per patient-year; P<.0001) and fewer invasive fungal infections (15 vs. 28 episodes; P=.04, by chi2 test), but not with improved survival, compared with episodic fluconazole therapy.

CONCLUSION

Continuous fluconazole therapy is not associated with significant risk of fluconazole-refractory OPC or EC, compared with episodic fluconazole therapy, in HIV-infected patients with access to active antiretroviral therapy.

Clinical utility of antifungal pharmacokinetics and pharmacodynamics

PURPOSE OF REVIEW

Historically the anti-infective dose and dosing interval chosen in clinical trials have been based on an arbitrary goal of maintaining drug levels in serum above the minimum inhibitory concentration of infecting pathogens for most if not all of the dosing interval. Subsequent United States Food and Drug Administration approval of a dosing regimen is then based on clinical success in treatment trials. Over the past decade, the emergence of drug resistance has limited the clinical utility of an increasing number of antimicrobial agents. However, early in drug development clinical trials do not often define the impact of infection with these less susceptible pathogens. The field of pharmacodynamics provides analysis tools that can help predict the likelihood of treatment success with various antimicrobial treatment regimens against susceptible and resistant pathogens.

RECENT FINDINGS

In-vitro and animal model studies have begun to define the pharmacodynamic characteristics of a variety of antifungal compounds. In-vivo studies have demonstrated that the pharmacodynamic target associated with efficacy is similar among antifungal drugs within the same class and have shown the importance of considering protein. Analysis of clinical trial data suggests that the pharmacodynamic target identified in animal model studies is predictive of outcomes in humans.

SUMMARY

Antifungal pharmacodynamics can be used to understand the relationship between drug dosing, in-vitro susceptibility and treatment efficacy. Consideration of these relationships can be used to optimize dosing regimens with current antifungal agents, to develop susceptibility breakpoint guidelines, and in the design of dosing regimens for drugs in early development.

Monochrome LightCycler PCR assay for detection and quantification of five common species of Candida and Aspergillus

Invasive fungal pathogens, especially in immunocompromised hosts, can result in life-threatening infections. Current laboratory/radiological methods for fungal identification are time-consuming and lack sensitivity and specificity. A monochrome, multiplex, real-time PCR assay for the identification and quantification of Candida albicans, Candida krusei, Candida tropicalis, Aspergillus flavus and Aspergillus fumigatus is described here. Detection of each of these fungi was specific and demonstrated 100 % concordance with biochemical/culture identification in all 60 isolates tested. Samples from 16 febrile neutropenic patients with haematological malignancies were also analysed and the utility of the assay in clinical samples was reconfirmed without false-negative results. The sensitivity of this assay was 0.1 pg fungal genomic DNA, corresponding to three cells, for C. albicans, C. krusei, C. tropicalis and A. flavus, and 0.01 pg fungal genomic DNA, i.e. less than one cell, for A. fumigatus. The analysis allows a low-cost, simple, rapid and sensitive alternative for clinical identification and quantification of these five common fungal species.

Optimal prophylactic dosage and disposition of micafungin in living donor liver recipients

Micafungin, a new candin antifungal drug, has a good safety profile and a significant therapeutic effect against Candida and Aspergillus. Little is known, however, about the optimal prophylactic dosage and the disposition of micafungin in liver transplant recipients, or about the effect of continuous venovenous hemodialysis (CVVH) on the pharmacokinetics of micafungin. Six living donor liver transplant patients were enrolled in this study. The mean C(max) and C(min) (trough) values of micafungin in plasma were 6.31 +/- 1.08 and 1.65 +/- 0.54 microg/mL, respectively. The mean elimination half-life (t(1/2)) and mean area under the curve up to 12 h post-dosing (AUC 0-12 h) were 13.63 +/- 2.77 h and 50.04 +/- 6.48 microg.h/mL, respectively. The concentrations of micafungin at the inlet and outlet of the dialyzer were very similar. The mean (+/-SD) ratio of micafungin concentrations at the inlet and outlet of the dialyzer (coutlet/cinlet) and the clearance of micafungin were 0.96 +/- 0.04 and 0.054 +/- 0.04 mL/min/kg, respectively. The amount in the ultrafiltrate was 1.0 mg. Micafungin effectively prevents systemic fungal infection in patients who have undergone liver transplantation. No significant differences were observed in the disposition of micafungin in recipients, and the therapeutic drug level can be achieved by administration of micafungin at a dosage of 40-50 mg/d. The CVVH had little effect on micafungin kinetics, and no dose adjustment or modification of dosing interval was needed during CVVH.

In vitro antifungal susceptibility of Candida spp. isolates from patients with chronic periodontitis and from control patients

Superinfection by Candida can be refractory to conventional periodontal treatments in specific situations, such as in immunocompromised patients. In these cases, the systemic therapy with antifungal drugs could be indicated. The aim of this study was to analyse antifungal susceptibility of Candida spp. strains isolated from chronic periodontitis patients and from control individuals. A total of 39 C. albicans isolates, 9 C. tropicalis, 2 C. glabrata and 5 Candida spp. from control individuals and 30 C. albicans, 3 C. tropicalis and 2 C. glabrata from periodontitis patients were tested. In the control group, 1 isolate of C. glabrata was resistant to ketoconazole and 1 Candida spp. was resistant to amphotericin B, ketoconazole and miconazole. Among the isolates of periodontitis group, 1 (3.33%) C. albicans isolate was resistant to flucytosine and ketoconazole. According to the obtained results, it could be concluded that fluconazole was the most effective drug against the several Candida species studied. There were not expressive differences in the susceptibility of isolates from periodontitis patients or from control individuals.

Caspofungin—a new therapeutic option for oropharyngeal candidiasis

Patients with AIDS are often severely immunocompromised. These patients commonly develop opportunistic infections such as oropharyngeal candidiasis whose treatment may prove to be difficult. Caspofungin belongs to a new class of antifungal agents that have a different mode of action to azoles and polyenes. This new agent is the first inhibitor of fungal glucan synthesis to receive approval for the treatment of mucosal and invasive candidiasis and invasive aspergillosis. Caspofungin is well-tolerated and represents a substantial improvement over existing therapeutic options for patients prone to azole-resistant candida infection or who cannot tolerate amphotericin B.

Clinical pharmacodynamics of antifungals

Application of pharmacodynamic principles to antifungal drugs has provided an understanding of the relationship between drug dosing and treatment outcomes similar to that observed in antibacterial pharmacodynamics. Initial observations with triazole pharmacodynamics have correlated with clinical trial results and proved useful for validation of in vitro susceptibility breakpoints. Pharmacodynamic studies have been invaluable for clinical trial dosing design for numerous antibacterial drugs in the development stage. More recently, pharmacodynamics has been used for the development of treatment guidelines. Although there remain many unanswered questions regarding antifungal pharmacodynamics, available data suggest usefulness in the application of pharmacodynamics to antifungal clinical development.

Efficacy of caspofungin in the treatment of esophageal candidiasis resistant to fluconazole

Caspofungin is a new echinocandin drug with comparable in vitro activity against azole-susceptible and -resistant isolates of that could provide a less toxic alternative to amphotericin B for the management of esophageal candidiasis with clinical or laboratory evidence of decreased susceptibility to fluconazole. The authors retrospectively analyzed its efficacy in adults with endoscopically documented esophagitis from four Phase II and III studies using two definitions of resistance to fluconazole: 1) clinically refractory infection based on failure of esophageal symptoms to improve despite at least 1 week of >or=200 mg/d of fluconazole; or 2) microbiologically resistant infection with either "susceptible dose-dependent" or "resistant" isolates based on MICs of 16 to 32 and >or=64 microg fluconazole/mL, respectively. A favorable response required resolution of all symptoms and substantial improvement in endoscopic findings. Seven of 11 patients (64%) who had been clinically refractory to fluconazole had favorable responses to caspofungin. Eleven of 14 patients (79%) whose isolates had decreased susceptibility to fluconazole had favorable responses to caspofungin, including 5 (83%) of 6 patients infected by isolates with MICs of >or=64 microg fluconazole/mL. Caspofungin appeared to be efficacious therapy for some patients with esophageal candidiasis who were clinically refractory to fluconazole or infected by with reduced susceptibility to fluconazole in vitro.

A randomized double-blind study of caspofungin versus fluconazole for the treatment of esophageal candidiasis

BACKGROUND

Candida esophagitis remains an important cause of morbidity in patients with advanced human immunodeficiency virus (HIV) infection. Fluconazole is widely regarded as the treatment of choice for this condition.

METHODS

The efficacy and safety of caspofungin were compared with fluconazole in adult patients with Candida esophagitis in a double-blind randomized trial. Eligible patients had symptoms compatible with esophagitis, endoscopic demonstration of mucosal plaques, and microscopic demonstration of Candida from the esophageal lesions. Patients were randomly assigned to receive caspofungin (50 mg) or fluconazole (200 mg) intravenously once daily for 7 to 21 days. The primary endpoint was the combined response of symptom resolution and significant endoscopic improvement 5 to 7 days after discontinuation of treatment. Data were analyzed with a modified intention-to-treat analysis, which excluded 2 ineligible patients.

RESULTS

Most patients (154/177; 87%) had HIV infection, with a median CD4 count of 30 cells/mm(3). Candida albicans was the predominant isolate. Favorable response rates were achieved in 66 (81%) of the 81 patients in the caspofungin arm and in 80 (85%) of the 94 patients in the fluconazole arm (difference = -4%; 95% confidence interval: -15% to +8%). Symptoms had resolved in >50% of patients in both groups by the fifth day of treatment. No patient in the caspofungin group developed a serious drug-related adverse event; therapy was only discontinued in 1 patient (receiving fluconazole) due to a drug-related adverse experience. Four weeks after stopping study drug, symptoms had recurred in 18 (28%) of 64 patients given caspofungin and in 12 (17%) of 72 patients given fluconazole (P = 0.19).

CONCLUSIONS

In this study, caspofungin appeared to be as efficacious and generally as well tolerated as fluconazole in patients with advanced HIV infection and documented Candida esophagitis.

Response and relapse rates of candidal esophagitis in HIV-infected patients treated with caspofungin

Caspofungin is a new antifungal drug of the echinocandin class. We analyzed the clinical efficacy of caspofungin (50 mg/day) in the treatment of HIV-infected adults with endoscopically documented Candida esophagitis and enrolled in four clinical trials of caspofungin. Symptoms were evaluated daily; a favorable outcome required complete resolution of all esophageal symptoms assessed at the time of discontinuation of therapy. Relapse was defined as recurrent symptoms during the subsequent 2 weeks. A multivariate logistic regression model was developed to identify potential factors (including severity of symptoms at presentation, CD4(+) cell count on entry, extent of disease [assessed endoscopically at baseline], causative Candida species, duration of therapy [overall and after resolution of symptoms], time on treatment before symptom resolution, and antifungal prophylaxis) that might predict symptomatic relapse in the 2 weeks following completion of therapy. The median CD4(+) lymphocyte count for the entire population was 31/mm(3). Candida albicans was isolated from 109 of 110 patient samples cultured for the pathogen and constituted the sole isolate in 77%. Extensive esophageal involvement was present in 55% of patients at the time of pretreatment endoscopy. The duration of therapy ranged from 7 to 20 days (median, 12 days). Symptoms resolved in 117 of 123 patients (95%; 95% confidence interval, 90-98%) with a median time of ~4 days. Response rates were 43 of 46 (93%) and 70 of 73 (96%) for patients with greater or fewer than 50 CD4(+) cells/mm(3), and 80 of 85 (94%) and 23 of 24 (96%) in infections caused by C. albicans alone or in association with non-albicans isolates, respectively. Symptoms recurred within 2 weeks of stopping caspofungin in 19 of 115 evaluable patients (17%), including 3 of 16 (19%) receiving antifungal prophylaxis. Relapse rates were similar for patients with greater or fewer than 50 CD4(+) cells/mm(3). In this relatively small number of patients, only symptom severity and extent of disease judged endoscopically at baseline were significantly (p < 0.10) associated with early relapse in the multivariate model.

Randomized, double-blind, multicenter study of caspofungin versus amphotericin B for treatment of oropharyngeal and esophageal candidiases

Caspofungin is an antifungal agent of the novel echinocandin class. We investigated its efficacy, safety, and tolerability as therapy for oropharyngeal and/or esophageal candidiasis in a phase II dose-ranging study. Patients were randomized in a double-blind manner to receive either caspofungin acetate (35, 50, or 70 mg) or amphotericin B (0.5 mg/kg of body weight) intravenously once daily for 7 to 14 days. A favorable response required both complete resolution of symptoms and quantifiable improvement of mucosal lesions 3 to 4 days after discontinuation of study drug. Efficacy was assessed using a modified intent-to-treat analysis. No hypothesis testing of efficacy was planned or performed. Of 140 enrolled patients, 63% had esophageal involvement and 98% were infected with the human immunodeficiency virus (HIV) (median CD4 count, 30/mm(3)). A modestly higher proportion of patients in each of the caspofungin groups (74 to 91%) achieved favorable responses compared to amphotericin B recipients (63%), but there was considerable overlap in the 95% confidence intervals surrounding these point estimates. Similar trends were found in the subgroups with esophageal involvement, a history of fluconazole failure, and CD4 counts of < or =50/mm(3). A smaller proportion of patients receiving any dose of caspofungin experienced drug-related adverse events compared to patients given standard doses of conventional amphotericin B (P < 0.01). Caspofungin provided a generally well-tolerated parenteral therapeutic option for HIV-infected patients with oropharyngeal and/or esophageal candidiasis in this study.

A randomized double-blind study of caspofungin versus amphotericin for the treatment of candidal esophagitis

Caspofungin is a new broad-spectrum antifungal drug. A multicenter, double-blind, randomized trial was conducted to assess the efficacy, safety, and tolerability of caspofungin relative to amphotericin B in adults with endoscopically documented symptomatic Candida esophagitis. By use of a modified intent-to-treat analysis, endoscopically verified clinical success was achieved in 74% (95% confidence interval [CI], 59%-86%) and 89% (95% CI, 72%-98%) of patients receiving caspofungin at 50 and 70 mg/day, respectively, and in 63% (95% CI, 49%-76%) of patients given amphotericin B at 0.5 mg/kg/day. Therapy was stopped because of drug-related adverse events in 24% of patients in the amphotericin B group and 4% and 7%, respectively, for the caspofungin groups. This report provides the first demonstration of clinical utility for an echinocandin compound. Caspofungin appeared in this study to be as effective as and better tolerated than amphotericin B for the treatment of esophageal candidiasis.

Susceptibilities of oral bacteria and yeast to mammalian cathelicidins

The effects of cathelicidins against oral bacteria and clinically important oral yeasts are not known. We tested the susceptibilities of Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, Streptococcus sanguis, Candida krusei, Candida tropicalis and Candida albicans to the following cathelicidins: FALL39, SMAP29, and CAP18. SMAP29 and CAP18 were antimicrobial, whereas FALL39 did not exhibit antimicrobial activity. Future studies are needed to determine the potential use of these antimicrobial peptides in prevention and treatment of oral infections.

Rapid identification of yeasts in positive blood cultures by a multiplex PCR method

Yeasts are emerging as important etiological agents of nosocomial bloodstream infections. A multiplex PCR method was developed to rapidly identify clinically important yeasts that cause fungemia. The method amplified the internal transcribed spacer 1 (ITS1) region between the 18S and 5.8S rRNA genes and a specific DNA fragment within the ITS2 region of Candida albicans. With this method, C. albicans produced two amplicons, whereas other species produced only one. Through sequence analysis, the precise lengths of the PCR products were found to be as follows: C. glabrata (482 or 483 bp), C. guilliermondii (248 bp), C. parapsilosis (229 bp), C. albicans (218 or 219 and 110 bp), C. tropicalis (218 bp), Cryptococcus neoformans (201 bp), and C. krusei (182 bp). The PCR products could be effectively separated by disk polyacrylamide gel electrophoresis. The method was used to test 249 positive blood cultures (255 isolates), from which the following species (strain number) were isolated: C. albicans (128), C. tropicalis (51), C. glabrata (28), C. parapsilosis (23), C. neoformans (9), C. krusei (5), C. guilliermondii (3), and other, minor species (8). The test sensitivity of the method was 96.9% (247 of 255 isolates). The eight minor species were either misidentified (one strain) or not identified (seven strains). From the time at which a positive bottle was found, the multiplex PCR could be completed within 8 h; the present method is simpler than any previously reported molecular method for the identification of blood yeasts.

Antifungal resistance among Candida species

Isolation of Candida sp less susceptible to traditional therapies and recovery of increasingly resistant isolates during antifungal therapy are growing problems. It is important for clinicians to be aware of trends and mechanisms responsible for the expression of resistance.

Evaluation of Etest for direct antifungal susceptibility testing of yeasts in positive blood cultures

The performance of the Etest (AB BIODISK, Solna, Sweden) for direct antifungal susceptibility testing of yeasts in positive blood cultures was compared with that of the macrodilution method for determining the MICs of five antifungal agents. Culture broths with blood from bottles positive for yeasts were inoculated directly onto plates for susceptibility testing with the Etest, and the MICs were read after 24 and 48 h of incubation. A total of 141 positive blood cultures (72 cultures of Candida albicans, 31 of Candida tropicalis, 14 of Candida glabrata, 11 of Candida parapsilosis, 3 of Candida krusei, and 3 of Cryptococcus neoformans, 4 miscellaneous yeast species, and 3 mixed cultures) were tested, and the rates of MIC agreement (+/-1 log(2) dilution) between the direct Etest (at 24 and 48 h, respectively) and macrodilution methods were as follows: amphotericin B, 81.8 and 93.5%; flucytosine, 84.8 and 87.7%; fluconazole, 89.4 and 85.5%; itraconazole, 69.7 and 63.8%; ketoconazole, 87.9 and 79.0%. By a large-sample t test, the difference in log(2) dilution between the direct Etest and the macrodilution method was found to be small (P < 0.05). The lone exceptions were ketoconazole at 48 h of incubation and itraconazole at both 24 and 48 h of incubation (P > 0.05). By Tukey's multiple comparisons, the difference between the direct Etest (48 h) and reference methods among different species was found to be less than 1 log(2) dilution. When the MICs were translated into interpretive susceptibility, the minor errors caused by the direct Etest (at 24 and 48 h, respectively) were as follows: flucytosine, 2.3 and 1.4%; fluconazole, 3.0 and 3.6%; itraconazole, 21.2 and 21.3%. Itraconazole also produced an additional 3.0 and 3.6% major errors as determined by the direct Etest at 24 and 48 h, respectively. It was concluded that, except for itraconazole, the Etest method was feasible for direct susceptibility testing of blood cultures positive for yeasts. The method is simple, and the results could be read between 24 and 48 h after direct inoculation, whenever the inhibition zones were discernible.

Clinical trial: clotrimazole troche vs. itraconazole oral solution in the treatment of oral candidosis in AIDS patients

This prospective study was designed to compare the efficacy and safety of itraconazole oral solution with those of clotrimazole troche in the treatment of oropharyngeal candidosis in acquired immunodeficiency syndrome (AIDS) patients. Patients were excluded if they had been treated with any antifungal agents 2 weeks prior to the study entry, were pregnant or nursing, or had significant liver disease. Twenty-nine patients (20 men and nine women), with a mean age of 32 years (15-62 years), were randomly, observer-blind treated with clotrimazole troche (10 mg, five times daily) or itraconazole oral solution (100 mg/10 mL, twice daily) for 1 week. Clinical and mycologic assessment were carried out on four consecutive days, in week 1, week 2, and week 4 after the start of treatment. Clinical evaluation was assessed by a scoring method (0-3, absent to severe) as follows: soreness, change in taste, erythema, removable white plaque, and extent of lesions. Mycologic assessment was performed by KOH preparation and fungal culture. Global evaluation, which is a summary of clinical and mycologic assessment at the end of treatment, was classified as cure (all signs and symptoms resolved with no evidence of infection), improvement (decrease in clinical score without complete resolution), or failure (lack of improvement or further deterioration). (Pons V, Greenspan D, Debruin M. Therapy for oropharyngeal candidiasis in HIV-infected patients: a randomized, prospective multicenter study of oral fluconazole versus clotrimazole troches. J Acquir Immune Defic Syndr 1993; 6: 1311-1316. ) Global evaluation at week 2 and week 4 was made in terms of no relapse or relapse. Any intercurrent medical events, whether human immunodeficiency virus (HIV)-related or not, were recorded. An intention-to-treat analysis was employed. Data were analyzed using the chi-squared test, Mann-Whitney U-test, and Student's t-test.

Amphotericin B oral suspension for fluconazole-refractory oral candidiasis in persons with HIV infection. Adult AIDS Clinical Trials Group Study Team 295

OBJECTIVE

To determine the efficacy and safety of amphotericin B oral suspension (ABOS) for the treatment of fluconazole refractory oral candidiasis in persons with HIV infection.

DESIGN AND SETTING

A prospective, multicenter, open label trial at 25 study centers within the AIDS Clinical Trials Group.

PATIENTS AND METHODS

Individuals with diffuse oral candidiasis after 14 days of treatment with 200 mg of fluconazole daily (more than five plaques or a single plaque > 3 cm largest length) were treated with ABOS, 100 mg/ml, 5 ml swish and swallow, four times daily for 14 days. Thereafter incomplete or non-responders received an additional 14 days of therapy and responders received maintenance ABOS twice daily for up to 6 months. Relapses during maintenance ABOS were treated by increasing the dose to four times daily.

MAIN OUTCOME MEASURES

To demonstrate an ABOS clinical response rate > 33% and a treatment-limiting toxicity rate < 50%. Clinical response was defined as the absence of mouth pain and the presence of less than five oral plaques, the largest being < 3 cm largest dimension.

RESULTS

Fifty-eight subjects with a median age of 39 years and a median CD4 count of 10 x 10(6) cells/l were enrolled. Four subjects were excluded from the analysis because of inadequate follow-up after randomization (n = 3) or the presence of active esophageal disease (n = 1). Of the remaining 54 subjects, 23 (42.6%; 95% lower confidence interval, 31.1%) were classified as responders after 28 days. Five subjects (9%) stopped treatment due to toxicity. Relapse occurred in 16 responders (70%).

CONCLUSIONS

Amphotericin B oral suspension is well tolerated but has limited efficacy for the treatment of fluconazole refractory oral candidiasis.

Refractory mucosal candidiasis in advanced human immunodeficiency virus infection

We conducted a multicenter, prospective study of the risk factors, natural history, and outcome of fluconazole-refractory mucosal candidiasis (FRMC) in 832 persons with advanced human immunodeficiency virus (HIV) infection (median CD4 cell count, 14/mm3) during 1994-1996. FRMC was defined as mucosal candidiasis that failed to resolve despite 14 days of therapy with daily doses (> or =200 mg) of fluconazole. Thirty-six persons (4.3%) had FRMC (35, oral; 1, esophageal), for an incidence of 4.2 per 100 person-years (859.7 total years of follow-up). In a multivariate model, the use of trimethoprim-sulfamethoxazole within 6 months of enrollment (relative risk [RR], 2.39; P=.04) and the use of fluconazole daily or every other day (RR, 5.64; P=.004) were significantly associated with the development of FRMC. The median survival after the development of FRMC was 32.6 weeks. In conclusion, the annual incidence of FRMC was <5%. Refractory candidiasis was a poor prognostic indicator. Daily or every-other-day use of fluconazole was associated with the development of refractory infection.

Antifungal susceptibility testing of yeasts: uses and limitations

With recent developments in the field of mycology, such as increased incidence of fungal infections, the introduction of newer, safer antifungals, and the emergence of resistance, the need for clinically relevant antifungal susceptibility testing methods is obvious. Studies performed over the past decade have allowed the National Committee for Clinical Laboratory Standards Subcommittee on Antifungal Testing to achieve consensus on a new standardized broth dilution method for in vitro susceptibility testing of yeasts (NCCLS M27-A). Once the reproducibility of the M27-A document was established, tentative breakpoints for fluconazole and itraconazole were derived. The availability of a standardized procedure for determining the minimum inhibitory concentrations (MICs) of antifungal agents is an important tool in drug discovery and development. In addition, it provides means for detection of resistant strains and, in the case of oropharyngeal candidiasis, means for patient management. Copyright 2000 Harcourt Publishers Ltd.

Options for the management of mucosal candidiasis in patients with AIDS and HIV infection

Oropharyngeal candidiasis may be the first manifestation of human immunodeficiency viral (HIV) infection, and more than 90% of patients with the acquired immunodeficiency syndrome (AIDS) develop the disease. Although numerous antifungal agents are available, azoles, both topical (clotrimazole) and systemic (fluconazole, itraconazole), have largely replaced older topical antifungals (gentian violet, nystatin) in the management of the disease in these patients. A concern in these patients is clinical relapse, which appears to be dependent on degree of immunosuppression and is more common with clotrimazole and ketoconazole than with fluconazole or itraconazole. Candida esophagitis is also of concern, since it occurs in more than 10% of patients with AIDS. Fluconazole is an integral part of management. A cyclodextrin oral solution formulation of itraconazole has similar clinical response rates as fluconazole and is an effective alternative. In patients with fluconazole-resistant mucocutaneous candidiasis, treatment options include itraconazole and amphotericin B oral suspension and parenteral preparation.

Candida glabrata: review of epidemiology, pathogenesis, and clinical disease with comparison to C. albicans

Until recently, Candida glabrata was considered a relatively nonpathogenic commensal fungal organism of human mucosal tissues. However, with the increased use of immunosuppressive agents, mucosal and systemic infections caused by C. glabrata have increased significantly, especially in the human immunodeficiency virus-infected population. A major obstacle in C. glabrata infections is their innate resistance to azole antimycotic therapy, which is very effective in treating infections caused by other Candida species. Candida glabrata, formerly known as Torulopsis glabrata, contrasts with other Candida species in its nondimorphic blastoconidial morphology and haploid genome. C. glabrata currently ranks second or third as the causative agent of superficial (oral, esophageal, vaginal, or urinary) or systemic candidal infections, which are often nosocomial. Currently, however, there are few recognized virulence factors of C. glabrata and little is known about the host defense mechanisms that protect against infection. Two established animal models (systemic and vaginal) have been established to study treatment, pathogenesis, and immunity. Treatment of C. glabrata infections can include azoles but often requires amphotericin B or flucytosine. This review summarizes all known clinical and experimental information about C. glabrata infections with comparisons to C. albicans as a means of contrasting the two species commonly observed and emphasizing the many recognized differences.

Isolation of Candida glabrata homologs of the Saccharomyces cerevisiae KRE9 and KNH1 genes and their involvement in cell wall beta-1,6-glucan synthesis

The Candida glabrata KRE9 (CgKRE9) and KNH1 (CgKNH1) genes have been isolated as multicopy suppressors of the tetracycline-sensitive growth of a Saccharomyces cerevisiae mutant with the disrupted KNH1 locus and the KRE9 gene placed under the control of a tetracycline-responsive promoter. Although a cgknh1Delta mutant showed no phenotype beyond slightly increased sensitivity to the K1 killer toxin, disruption of CgKRE9 resulted in several phenotypes similar to those of the S. cerevisiae kre9Delta null mutant: a severe growth defect on glucose medium, resistance to the K1 killer toxin, a 50% reduction of beta-1,6-glucan, and the presence of aggregates of cells with abnormal morphology on glucose medium. Replacement in C. glabrata of the cognate CgKRE9 promoter with the tetracycline-responsive promoter in a cgknh1Delta background rendered cell growth tetracycline sensitive on media containing glucose or galactose. cgkre9Delta cells were shown to be sensitive to calcofluor white specifically on glucose medium. In cgkre9 mutants grown on glucose medium, cellular chitin levels were massively increased.

Triazole therapy for mucocutaneous candidiasis in HIV-infected patients

Mucocutaneous candidiasis, such as oropharyngeal candidiasis, esophageal candidiasis, and vulvovaginal candidiasis, are common problems in patients with HIV infection. These conditions adversely affect patient quality of life and morbidity status. New oral triazole agents provide improved treatment options for patients with these and other opportunistic fungal infections; however, the development of resistance in some Candida species poses new challenges. This article provides an overview of the diagnosis of mucocutaneous candidiasis, current treatment modalities, concomitant drug interactions, common adverse drug reactions, and the emergence of fungal resistance, and it suggests nursing interventions to maximize patient benefits from antifungal therapy.

A controllable gene-expression system for the pathogenic fungus Candida glabrata

A system for controlling gene expression was established in the pathogenic fungus Candida glabrata to elucidate the physiological functions of genes. To control the expression of the gene of interest, the C. glabrata cells were first transformed with the plasmid carrying the tetracycline repressor-transactivator fusion tetR::GAL4, then with the DNA fragment containing the controllable cassette, the tetracycline operator chimeric promoter (tetO::ScHOP1). The peptide elongation factor 3 (CgTEF3) and DNA topoisomerase II (CgTOP2) genes from C. glabrata were cloned and their expression assessed using this system. When the promoter of CgTEF3 or CgTOP2 was replaced with tetO::ScHOP1, doxycycline almost completely repressed the expression of both mRNAs, and impaired growth. Repression of the TOP2 or TEF3 gene by doxycycline also hampered the survival of C. glabrata cells in mice; in mouse kidneys the number of C. glabrata cells, in which the TOP2 or TEF3 promoter was replaced with the tetO::ScHOP1 controllable cassette, did not increase when the mice were given doxycycline. Thus, it appears that the gene repression mediated by doxycycline occurred not only in culture media but also in animals; therefore, this system can be used to elucidate the function of the gene in fungal infections and pathogenesis.

Extensive skin candidosis in an adult: effective treatment with itraconazole

A 34-year-old man with 6 years' untreated erythematous scaling of the skin was diagnosed as having extensive skin candidosis. Oral itraconazole was administered for 4 weeks (400 mg day-1 for the first 3 weeks and 200 mg day-1 for the last week). At the end of the 4-week treatment period, the rash was completely cleared from all skin sites, and Candida albicans was absent in culture tests on tissue samples. No adverse events were reported by the patient, and laboratory analysis revealed no abnormalities in the liver, kidney and haematological systems. Oral itraconazole is therefore an effective treatment for extensive skin candidosis.

Thirteen-year evolution of azole resistance in yeast isolates and prevalence of resistant strains carried by cancer patients at a large medical center

Drug resistance is emerging in many important microbial pathogens, including Candida albicans. We performed fungal susceptibility tests with archived isolates obtained from 1984 through 1993 and fresh clinical isolates obtained from 1994 through 1997 by testing their susceptibilities to fluconazole, ketoconazole, and miconazole and compared the results to the rate of fluconazole use. All isolates recovered prior to 1993 were susceptible to fluconazole. Within 3 years of widespread azole use, we detected resistance to all agents in this class. In order to assess the current prevalence of resistant isolates in our hematologic malignancy and transplant patients, we obtained rectal swabs from hospitalized, non-AIDS, immunocompromised patients between June 1995 and January 1996. The swabs were inoculated onto sheep's blood agar plates containing 10 microg of vancomycin and 20 microg of gentamicin/ml of agar. One hundred one yeasts were recovered from 97 patients and were tested for their susceptibilities to amphotericin B, fluconazole, flucytosine, ketoconazole, and miconazole. The susceptibility pattern was then compared to those for all clinical isolates obtained throughout the medical center. The antifungal drug histories for each patient were also assessed. The yeasts from this surveillance study were at least as susceptible as the overall hospital strains. There did not appear to be a direct linkage between prior receipt of antifungal agent therapy and carriage of a new, drug-resistant isolate. Increased resistance to newer antifungal agents has occurred at our medical center, but it is not focal to any high-risk patient population that we studied. Monitoring of susceptibility to antifungal agents appears to be necessary for optimizing clinical therapeutic decision making.

Clinical, cellular, and molecular factors that contribute to antifungal drug resistance

In the past decade, the frequency of diagnosed fungal infections has risen sharply due to several factors, including the increase in the number of immunosuppressed patients resulting from the AIDS epidemic and treatments during and after organ and bone marrow transplants. Linked with the increase in fungal infections is a recent increase in the frequency with which these infections are recalcitrant to standard antifungal therapy. This review summarizes the factors that contribute to antifungal drug resistance on three levels: (i) clinical factors that result in the inability to successfully treat refractory disease; (ii) cellular factors associated with a resistant fungal strain; and (iii) molecular factors that are ultimately responsible for the resistance phenotype in the cell. Many of the clinical factors that contribute to resistance are associated with the immune status of the patient, with the pharmacology of the drugs, or with the degree or type of fungal infection present. At a cellular level, antifungal drug resistance can be the result of replacement of a susceptible strain with a more resistant strain or species or the alteration of an endogenous strain (by mutation or gene expression) to a resistant phenotype. The molecular mechanisms of resistance that have been identified to date in Candida albicans include overexpression of two types of efflux pumps, overexpression or mutation of the target enzyme, and alteration of other enzymes in the same biosynthetic pathway as the target enzyme. Since the study of antifungal drug resistance is relatively new, other factors that may also contribute to resistance are discussed.

[Fluconazole-resistant Candida species from HIV infected patients with recurrent Candida stomatitis: cross resistance to itraconazole and ketoconazole]

In vitro susceptibility to fluconazole of Candida species isolated from 83 HIV-infected patients treated with fluconazole because of recurrent Candida stomatitis was monitored over a period of two years. A microdilution assay with high-resolution antifungal assay (HR) medium and RPMI 1640-medium were compared. In vitro less susceptible and fluconazole resistant C. species were observed in 23 patient at the end of the study. The Candida isolates recovered from oral rinsing fluids at the beginning and the end of study were tested for crossresistance to itraconazole and ketoconazole. Susceptibility to ketoconazole and to itraconazole was reduced using RPMI 1640-medium. Susceptibility of the isolates to fluconazole was not influenced by the assay medium. In 21 patients in vitro fluconazole resistant or less susceptible C. albicans were observed. 9 of 21 isolates showed crossresistance to itroconazole and ketoconazole, in 10 isolates only crossresistance to itraconazole was observed. During fluconazole treatment double infections due to combination of C. albicans and C. glabrata or C. krusei increased from 20% to 78% C. krusei was resistant to the three azoles. C. glabrata was less susceptible (4-8 mg/l) or resistant (> 8 mg/l) to fluconazole and resistant to itraconazole and ketoconazole High dosed intravenous fluconazole treatment with 400 to 600 mg daily failed in 11 patients with fluconazole resistant C. albicans and in 3 (3/10) patients with les susceptible C. albicans isolates.

Randomized trial of itraconazole oral solution for oropharyngeal candidiasis in HIV/AIDS patients

PURPOSE

Oropharyngeal candidasis (thrush) is the most common opportunistic infection in individuals who are positive for the human immunodeficiency virus (HIV) and those who have progressed to AIDS. Itraconazole has a broad in vitro spectrum of activity, including a wide variety of Candida species. Our study determined the relative efficacy of a new oral solution formulation of itraconazole and fluconazole tablets in the treatment of oropharyngeal candidiasis.

PATIENTS AND METHODS

This was a prospective randomized, third-party-blind, multicenter trial conducted at 12 centers in the United States. One hundred seventy-nine HIV-positive patients with mycologically documented oropharyngeal candidiasis were treated with itraconazole oral solution 200 mg/ day for 7 or 14 days, or fluconazole tablets 100 mg/day for 14 days. Severity of disease was scored clinically before treatment and at clinical evaluations on days 3, 7, 14, 21, 35, and 42. Semi-quantitative cultures of mouth washings were also obtained on these days.

RESULTS

Both 14-day and 7-day regimens of itraconazole oral solution were equivalent to fluconazole for most efficacy parameters. The clinical response rate was 97% after 14 days of itraconazole and 87% after 14 days of fluconazole. Itraconazole oral solution given for 7 days was also equivalent to fluconazole treatment for 14 days. Approximately one half of patients in all three groups relapsed by 1 month after completion of treatment. There were few adverse reactions to either drug.

CONCLUSION

Itraconazole oral solution is well tolerated and offers an alternative at least as effective as fluconazole in the treatment of oropharyngeal candidiasis.

Oropharyngeal candidiasis: a review of its clinical spectrum and current therapies

With the increased use of antibiotics and immunosuppressive agents, oropharyngeal candidiasis is becoming more common. This infection is also associated with such advances in medical management as chemotherapy and organ transplantation and with human immunodeficiency virus infection. Various topical and systemic agents are available to treat patients with candidiasis, but optimal management can be elusive. Treatment of uncomplicated oropharyngeal candidiasis in the immunocompetent patient involves selecting a particular formulation of a topical medication based on oral conditions, length of contact time, and taste, texture, and cost of the medication. Treatment of severe oropharyngeal candidiasis, particularly in patients with a compromised immune system, is often more difficult, and relapses are common. Reports of resistance to systemic agents, particularly in patients needing recurrent therapy, are increasing. Amphotericin B, long used as an intravenous agent, is now available as an oral suspension that may offer therapeutic benefits comparable to those of systemic therapy without the toxicity associated with systemic absorption.

Clinical relevance of antifungal resistance

The availability of standard guidelines (NCCLS M27 document) for antifungal susceptibility testing has facilitated the establishment of tentative interpretive breakpoints for fluconazole and itraconazole by the NCCLS. Based on correlations of MIC values with the outcomes of patients with mostly Candida infections, fluconazole MICs of > or = 64 and itraconazole MICs of > or = 1.0 microgram/mL are considered resistant. Fluconazole MICs of 16 to 32 micrograms/mL and itraconazole MICs of 0.2 to 0.5 microgram/mL were categorized as "susceptible dependent upon dose" (S-DD), that is, clinical response may be obtained with increased doses. Susceptible breakpoints for fluconazole and itraconazole correspond to < or = 8 and < or = 0.12 microgram/mL, respectively. For flucytosine, resistant and susceptible breakpoints for Candida were set at > or = 32 micrograms/mL and 4 micrograms/mL, respectively, based on historical data and the drug's pharmacokinetics for Candida. Although no breakpoints have been established for amphotericin B, clinical failure has been associated with MICs > 1.0 microgram/mL.

Antifungal resistance trends towards the year 2000. Implications for therapy and new approaches

Medical advances have led to increased numbers of immunocompromised patients living longer. Coinciding with this increase in the immunocompromised patient population is an increase in the number of clinically significant fungal infections. Unfortunately, widespread use of the limited numbers of antifungal agents to treat these infections has led to the development of drug resistance. Thus, in an attempt to sort out the mechanisms of resistance for each of the systemically useful antifungal agents, a comprehensive review of the literature has been carried out. The most common mechanisms for the development of resistance involve changes in the enzymatic pathways which serve as the drug targets. For instance, changes in enzymes responsible for the biosynthesis of ergosterol, the target of azole activity, lead to azole resistance. Another common mechanism used by fungi to avoid drug toxicity includes reduced intracellular accumulation of the drug through both decreased permeability and energy-dependent efflux pumps. Using our current understanding of the mechanisms of drug resistance as a template, several strategies to overcome resistance have been identified. These include improvement of host immune function, the use of adjuvant surgery, the development of new drug delivery systems for currently available drugs and the development of new classes of antifungal agents. Also, clinical trials to establish appropriate drug doses and duration of therapy are needed, as well as the benefits of antifungal prophylaxis explored and the use of combination therapies entertained. The war against drug resistant fungi has been identified as we approach the year 2000. With careful and cogent investigations, we do have the tools to fight back against these opportunists. Of all the strategies reviewed, however, in our opinion, the development of new antifungal drugs is likely to have the most significant future impact on our management of drug resistance in fungal infections.

Preventing and treating major opportunistic infections in AIDS. What's new and what's still true

New highly active antiretroviral therapies are boosting the blood absolute CD4+ counts of many patients with AIDS and are decreasing the prevalence of AIDS-related opportunistic infections. Nevertheless, the prevention, diagnosis, and treatment of opportunistic infections remain important features of management of HIV infection. In recent years, significant advances have been made in the prevention and treatment of opportunistic diseases such as Pneumocystis carinii pneumonia, Cytomegalovirus retinitis, disseminated Mycobacterium avium-intracellulare infection, and mucosal candidiasis. Tuberculosis, cryptococcal meningitis, herpes simplex virus infection, shingles, and infectious enteritis also continue to be troublesome. Kaposi's sarcoma may be the newest AIDS-related opportunistic infection to be identified. The immune system effects of highly active antiretroviral therapy are as yet poorly understood. Therefore, an aggressive approach to diagnosis and treatment of opportunistic infections remains mandatory, and patients receiving antiretroviral therapy should continue to adhere to recommendations for prophylaxis against such infections.

Update on antifungal resistance

Overuse of antifungal agents has resulted in the selection of naturally resistant Candida species, as well as expression of resistance from previously susceptible species resulting from genetic mutations and/or selection of resistant subpopulations. Strategies for the appropriate use of antifungal agents need to be developed to prevent further development of resistance.