Laboratory evaluation of new antifungal agents against rare and refractory mycoses

Severe prosthetic joint infection in an immunocompetent male patient due to a therapy refractory Pseudallescheria apiosperma

Prosthetic joint infections (PJI) are rarely due to fungal agents and if so they are mainly caused by Candida strains. This case represents a PJI caused by a multi-drug resistant Pseudallescheria apiosperma, with poor in vivo response to itraconazole and voriconazole. This case differs also by the way of infection, since the joint infection did not follow a penetrating trauma. In the majority of cases, Scedosporium extremity infections remain local in immunocompetent individuals. We report a persistent joint infection with multiple therapeutic failures, and subsequent amputation of the left leg. Detailed clinical data, patient history, treatment regime and outcome of a very long-lasting (>4 years) P. apiosperma prosthetic knee infection in an immunocompetent, 61-year-old male patient are presented with this case. The patient was finally cured by the combination of multiple and extensive surgical interventions and prolonged antifungal combination therapy with voriconazole and terbinafine.

Paradoxical growth effects of the echinocandins caspofungin and micafungin, but not of anidulafungin, on clinical isolates of Candida albicans and C. dubliniensis

OBJECTIVES

To analyze the effects of a high concentration of three antifungal substances, the echinocandins anidulafungin, caspofungin, and micafungin, on the growth of Candida spp.

METHODS

The growth of 127 C. dubliniensis isolates and 103 C. albicans isolates cultured in medium containing anidulafungin, caspofungin, or micafungin was analyzed using a broth microdilution test according to the guidelines of the CLSI M27-A2 [NCCLS (1997), Wayne, PA]. The final concentrations of all three echinocandins ranged from 0.125 to 64 microg/L.

RESULTS

The different effects of these three antifungal substances on C. albicans cells in comparison to C. dubliniensis cells were quite distinct. When both Candida species were grown in the presence of anidulafungin only a trailing effect was observed. Micafungin induced an Eagle effect in C. dubliniensis only (63%), while caspofungin induced this effect in the majority of C. dubliniensis isolates (90%) and in only a few C. albicans isolates (14%).

CONCLUSIONS

Based on our observations, anidulafungin has effects that are different from the ones produced by micafungin and caspofungin. Whether this different response to high concentrations of echinocandins is based on genetic or phenotypic differences between C. albicans and C. dubliniensis has to be determined in future experiments.

Caspofungin for the treatment of fungal infections: a systematic review of randomized controlled trials

During the last decade, owing to the low effectiveness and high toxicity of older antifungals, new antifungal agents have been released to the market for the treatment of patients with fungal infections. Several randomized controlled trials (RCTs) have been designed to evaluate the effectiveness of caspofungin in comparison with other antifungal agents. This review was conducted to examine further the role of caspofungin in the treatment of patients with fungal, mainly Candida, infections. Two reviewers independently performed the literature search, study selection and data extraction from relevant RCTs. A total of six RCTs comparing caspofungin with amphotericin B (deoxycholate in four and liposomal in one RCT) or fluconazole (in one RCT), which studied a total of 1974 patients, were included in our review. Success of the applied treatment in the clinically evaluable patients was achieved in 496/943 (52.6%) of the caspofungin-treated patients and in 381/852 (44.7%) of the amphotericin B- and lipid amphotericin B-treated patients. Discontinuation due to drug toxicity was significantly less common in patients receiving caspofungin than amphotericin B (odds ratio (OR) 0.25, 95% confidence interval (CI) 0.07-0.85, random effects model). Development of nephrotoxicity, hypokalaemia and fever also occurred significantly less often with caspofungin than amphotericin B (OR 0.23, 95% CI 0.14-0.36, fixed effects model; OR 0.3, 95% CI 0.12-0.76, random effects model; and OR 0.26, 95% CI 0.08-0.79, random effects model, respectively). No difference in mortality was noted. Caspofungin was associated with better clinical outcomes (higher cure and fewer adverse effects) than amphotericin B in the treatment of patients with fungal infections.

Emerging azole antifungals

Systemic and superficial fungal infections have progressively emerged over the past few decades as an increasing cause of human disease, especially in the immunocompromised host. Control of fungal disease has proved difficult because few risk factors are potentially preventable; the population at highest risk for fungal disease, the immunocompromised patient, has been steadily increasing. There is a clear need for additional safe and effective therapeutic agents for the treatment of systemic fungal disease. A new generation of triazoles that includes voriconazole, posaconazole, ravuconazole and albaconazole has emerged and are presently in different phases of clinical investigation. These new triazoles have demonstrated a broad spectrum of activity, in particular against fungal pathogens previously resistant to previously available antifungals. This review highlights the emerging azole antifungals, both those available and in clinical development, and discusses their prospects for the future.

Posaconazole treatment of refractory eumycetoma and chromoblastomycosis

Eumycetoma and chromoblastomycosis are chronic, disfiguring fungal infections of the subcutaneous tissue that rarely resolve spontaneously. Most patients do not achieve sustained long-term benefits from available treatments; therefore, new therapeutic options are needed. We evaluated the efficacy of posaconazole, a new extended-spectrum triazole antifungal agent, in 12 patients with eumycetoma or chromoblastomycosis refractory to existing antifungal therapies. Posaconazole 800 mg/d was given in divided doses for a maximum of 34 months. Complete or partial clinical response was considered a success; stable disease or failure was considered a nonsuccess. All 12 patients had proven infections refractory to standard therapy. Clinical success was reported for five of six patients with eumycetoma and five of six patients with chromoblastomycosis. Two patients were reported to have stable disease. As part of a treatment-use extension protocol, two patients with eumycetoma who initially had successful outcome were successfully retreated with posaconazole after a treatment hiatus of > 10 months. Posaconazole was well tolerated during long-term administration (up to 1015 d). Posaconazole therapy resulted in successful outcome in most patients with eumycetoma or chromoblastomycosis refractory to standard therapies, suggesting that posaconazole may be an important treatment option for these diseases.

Advances and challenges in management of invasive mycoses

Invasive mycoses pose a major diagnostic and therapeutic challenge. Advances in antifungal agents and diagnostic methods offer the potential for improved outcomes in patients with these infections, which are often lethal. Many fungal pathogens occur almost exclusively in opportunistic settings--in the immunocompromised host--and these infections are the focus of this review. Several areas of ongoing challenge remain, including the emergence of resistant organisms and the absence of reliable markers for early identification of patients at risk of developing invasive fungal disease. This Seminar reviews the changing epidemiology of invasive mycoses, new diagnostic methods, and recent therapeutic options and current management strategies for these opportunistic pathogens.

Activity of posaconazole in the treatment of central nervous system fungal infections

OBJECTIVES

A multinational, multicentre, open-label clinical trial was conducted to evaluate the safety and efficacy of posaconazole, an extended-spectrum triazole antifungal agent, in subjects with invasive fungal infections who had refractory disease or who were intolerant of standard antifungal therapy. In this subanalysis, we report on those subjects in this trial who had a fungal infection that involved the CNS.

METHODS

Subjects received posaconazole oral suspension 800 mg/day in divided doses for up to 1 year; however, subjects could receive additional therapy as part of a treatment-use extension protocol. A blinded, third-party data review committee determined subject eligibility and outcome.

RESULTS

Of the 330 subjects who enrolled in the study, 53 had infections of the CNS, of which 39 were considered evaluable for efficacy. Most had refractory disease (37 of 39) and underlying HIV infection (29 of 39). Twenty-nine subjects had cryptococcal infections, and 10 had infections caused by other fungal pathogens [Aspergillus spp. (four), Pseudallescheria boydii (two), Coccidioides immitis (one), Histoplasma capsulatum (one), Ramichloridium mackenziei (one), and Apophysomyces elegans plus a Basidiomycetes sp. (one)]. Successful outcomes were observed in 14 of 29 (48%) subjects with cryptococcal meningitis and five of 10 (50%) subjects with CNS infections due to other fungal pathogens. Posaconazole was well tolerated.

CONCLUSIONS

These data suggest that posaconazole, as an oral medication, has clinical activity against fungal infections of the CNS and may provide a valuable alternative to parenteral therapy in patients failing existing antifungal agents.

Fusarium peritonitis concomitant to kidney transplantation successfully managed with voriconazole: case report and review of the literature

Fusarium infections in solid organ transplant recipients are often localized, occur later in the post-transplantation period, and have a better outcome than fusarial infections in patients with hematologic malignancies or bone marrow transplants. We report the first case of proven peritonitis caused by Fusarium species in a renal transplant recipient which is also the first successfully managed with voriconazole. We also review previously reported cases of fusarial infection in solid organ transplant recipients.

Photoaging and phototoxicity from long-term voriconazole treatment in a 15-year-old girl

Voriconazole is a second-generation triazole that was approved by the Food and Drug Administration in May 2002 for treatment of severe fungal infections. In clinical trials it demonstrated superior efficacy in addition to a survival benefit when compared with the then current treatment standard, amphotericin B, for primary treatment of invasive aspergillosis. Voriconazole is a highly selective inhibitor of fungal cytochrome P450 enzymes. Adverse cutaneous reactions have been reported, namely cheilitis, erythema, discoid lupus erythematosus, Stevens-Johnson syndrome, toxic epidermal necrolysis, erythema multiforme, and photosensitivity reactions. We report a case of photoaging caused by voriconazole therapy. A 15-year-old patient developed cheilitis and erythema over the sun-exposed areas of her body 5 weeks after beginning voriconazole for a severe fungal infection. The lesions showed a mild transient improvement before subsequent photodamage occurred to the back of her forearms, back of her hands, and face. Voriconazole was discontinued once the fungal infection had completely resolved. The patient's blisters, erythema, and cheilitis resolved after discontinuation of voriconazole. However, she was left with solar elastotic changes, multiple lentigines, and ephelides of sun-exposed areas. These cutaneous manifestations may represent a unique adverse event caused by a new second-generation triazole.

Sepsis associated with immunosuppressive medications: an evidence-based review

OBJECTIVE

In 2003, critical care and infectious disease experts representing 11 international organizations developed management guidelines for sepsis associated with immunosuppressive medications that would be of practical use for the bedside clinician, under the auspices of the Surviving Sepsis Campaign, an international effort to increase awareness and improve outcome in severe sepsis.

DESIGN

The process included a modified Delphi method, a consensus conference, several subsequent smaller meetings of subgroups and key individuals, teleconferences, and electronic-based discussion among subgroups and among the entire committee.

METHODS

The modified Delphi methodology used for grading recommendations built on a 2001 publication sponsored by the International Sepsis Forum. We undertook a systematic review of the literature graded along five levels to create recommendation grades from A to E, with A being the highest grade. Pediatric considerations to contrast adult and pediatric management are in the article by Parker et al. on p. S591.

CONCLUSION

Immunosuppressed patients, by definition, are susceptible to a wider spectrum of infectious agents than immunologically normal patients and, thus, require a broader spectrum antimicrobial regimen when they present with sepsis or septic shock. Special expertise managing immunosuppressed patient populations is needed to predict and establish the correct diagnosis and to choose appropriate empiric and specific agents and maximize the likelihood that patients will survive these microbial challenges.

High-throughput detection of pathogenic yeasts of the genus trichosporon

The need for a rapid and accurate method for the detection of fungal pathogens has become imperative as the incidence of fungal infections has increased dramatically. Herein, we tested the Luminex 100, a novel flow cytometer, for the detection of the medically important genus Trichosporon. This genus was selected as our proof-of-concept model due to the close phylogenetic relationship between the species. The method, which is based on a nucleotide hybridization assay, consists of a combination of different sets of fluorescent beads covalently bound to species-specific capture probes. Upon hybridization, the beads bearing the target amplicons are classified by their spectral addresses with a 635-nm laser. Quantitation of the hybridized biotinylated amplicon is based on fluorescence detection with a 532-nm laser. We tested in various multiplex formats 48 species-specific and group-specific capture probes designed in the D1/D2 region of ribosomal DNA, internal transcribed spacer regions, and intergenic spacer region. Species-specific biotinylated amplicons were generated with three sets of primers to yield fragments from the three regions. The assay was specific and fast, as it discriminated species differing by 1 nucleotide and required less than 50 min following amplification to process a 96-well plate. The sensitivity of the assay allowed the detection of 10(2) genome molecules in PCRs and 10(7) to 10(8) molecules of biotinylated amplification product. This technology provided a rapid means of detection of Trichosporon species with the flexibility to identify species in a multiplex format by combining different sets of beads.

Utility of mould susceptibility testing

PURPOSE OF REVIEW

As new antifungal agents were introduced for the treatment of fungal infections, reliable methods were developed or adapted for the in-vitro susceptibility testing of yeasts and moulds (filamentous fungi). This paper reviews the available methods for antifungal susceptibility testing of moulds as well as the scant data that have been published since 2002 regarding the clinical implications of in-vitro testing.

RECENT FINDINGS

Caspofungin and voriconazole have been recently licensed for treatment of certain mould infections that are usually refractory to treatment with established agents. The introduction of new agents and the frequent reports of mould resistance have underscored the role of the laboratory in patient management and initiated the study of mechanisms of resistance in moulds. In 2002, the US National Committee for Clinical Laboratory Standards M38-P document moved to the approved level of development (M38-A document). Although combination therapy and synergistic studies with the new agents have been documented, very little information is available on in-vitro/in-vivo correlations for moulds.

SUMMARY

The ultimate goal of in-vitro testing is the prediction of the clinical outcome of therapy. The use of National Committee for Clinical Laboratory Standards procedures has led to increased interlaboratory agreement of minimum inhibitory concentrations. Reproducibility of minimum inhibitory concentrations for yeasts has facilitated the establishment of interpretive breakpoints for fluconazole and itraconazole versus Candida spp., but breakpoints are not available for any antifungal against mould species. Although some insights have been documented regarding the potential utility of in-vitro testing for moulds, further documentation of in-vitro versus in-vivo data is needed.

Emerging moulds: Fusarium, Scedosporium and Zygomycetes in transplant recipients

PURPOSE OF REVIEW

The incidence of non-Aspergillus mould infections in transplant recipients has increased over the past decade. This paper will review recent data regarding the epidemiology, clinical manifestations, treatment and the outcome of infections caused by Fusarium spp., Scedosporium spp. and the Zygomycetes in transplant recipients.

RECENT FINDINGS

Although the reasons for the increased incidence of non-Aspergillus mould infections in transplant recipients are not very clear, changes in transplant procedures, resulting in more severe immunosuppression, seem to play a major role, as suggested by recent epidemiologic data. Infections caused by these fungi have a tendency to be disseminated, and the prognosis is usually poor because the fungi are resistant to most of the available antifungal agents. New drugs, particularly the new azoles, may have a role in the treatment and prophylaxis of these infections, but the available data are still scant.

SUMMARY

The understanding of the changing epidemiology of fungal infections and their implications for the prognosis of transplant recipients are important to better evaluate the impact of new transplant procedures.

Status of combination therapy for refractory mycoses

PURPOSE OF REVIEW

Invasive fungal infections remain a leading cause of infectious morbidity and mortality in heavily immunosuppressed patients. As the efficacy of current antifungal agents is suboptimal, combinations of antifungal agents, administered concomitantly or sequentially, are increasingly used (mostly empirically) as a strategy to improve the treatment outcomes for refractory mycoses. Here we review recent developments in the area of antifungal combinations based on both laboratory (in vitro and in animal models) and clinical studies.

RECENT FINDINGS

With the exception of cryptococcal meningitis, the benefits of combination antifungal therapy have been more difficult to prove for other life-threatening mycoses such as invasive candidiasis or invasive aspergillosis. The recent introduction of a new class of antifungal agents (the echinocandins) and of extended spectrum triazoles has renewed interest in studying antifungal combinations that may result in additive or synergistic effects in difficult-to-treat mycoses. The combination of an echinocandin plus amphotericin B or a newer triazole seems to be the most promising in vitro and in animal model studies, whereas reliable clinical information especially for invasive mould infections is still lacking.

SUMMARY

Antifungal combinations are conceptually appealing as a strategy to overcome the frequent failures of antifungal monotherapy in immunosuppressed patients with invasive mycoses. Results of in-vitro studies cannot yet be translated into measurable clinical results because of methodological problems and the complexity of designing relevant prospective clinical trials, but important findings are expected in the near future in this rapidly expanding investigational area.