Treatment of aspergillosis: clinical practice guidelines of the Infectious Diseases Society of America

Therapeutic drug monitoring of voriconazole in a child with invasive aspergillosis requiring extracorporeal membrane oxygenation

We describe a patient with invasive pulmonary aspergillosis on extracorporeal membrane oxygenation therapy in which therapeutic drug monitoring and individualization of therapy by measuring voriconazole plasma concentrations were performed.

Antifungal therapy of Aspergillus invasive otitis externa: efficacy of voriconazole and review

Invasive otitis externa (IOE) due to Aspergillus is a rare, potentially life-threatening, invasive fungal infection affecting immunocompromised patients. The invasive process may lead to skull base osteomyelitis with progressive cranial nerve palsies and can result in irreversible hearing and neurological impairment. We report two cases of Aspergillus IOE treated with voriconazole alone and a literature review of antifungal therapy of Aspergillus IOE. Twenty-five patients, including the two described in the present report, were analyzed. Eighteen patients were treated with amphotericin B, and nine of them received itraconazole as an additional agent. Three patients received initial therapy with itraconazole, and one patient was treated with both voriconazole and caspofungin therapy. The two patients in the present report received voriconazole therapy alone with good clinical and biological tolerance despite prolonged treatment. The last patient did not receive antifungal therapy, as the diagnosis was made postmortem. Eighteen patients underwent an initial extensive surgical debridement. The majority of the patients had a favorable outcome, 17 patients experienced a complete recovery, and 6 showed a partial improvement. Both of the patients reported on here had favorable outcomes, and no aggressive surgical debridement was required. Although voriconazole has been shown to be effective for the treatment of invasive aspergillosis, its precise role in the management of Aspergillus IOE had not been documented. These observations demonstrate that voriconazole could be an effective and well-tolerated therapeutic option for the management of Aspergillus IOE.

Recognizing therapeutic failure

Cases are presented that raise the issue of how to recognize treatment failure, including radiologic, serologic, and/or clinical definitions with special attention to assessment when available information is conflicting or ambiguous. Just as the diagnosis of invasive aspergillus (IA) remains difficult to secure for many patients, so too is the assessment of a patient for possible treatment failure. Specifically the absence of a sensitive surrogate marker to monitor response leaves clinicians with several insensitive, non-specific and often conflicting pieces of information. For example, CT evidence of response is well-described to lag at least a week behind patient improvement and so this modality cannot be relied upon to assess daily or even weekly patient response. The clinical assessment of the patient is complicated by the presence or absence of neutropenia since patients may appear to worsen as their neutropenia recovers; conversely, patients with advanced infection may exhibit only subtle signs of IA if profoundly immunosuppressed. Finally, IA does not respond to any antifungal quickly; thus the clinician must patiently wait longer than is typical for a bacterial infection to determine whether the response is slow or simply not present. Assessment of a patient with IA for treatment failure is a complicated determination that requires the clinician to synthesize incomplete and often conflicting information. Further adding to the difficulty are the morbidity and mortality of the disease and the relative lack of effectiveness of the available antifungal agents.

Serial plasma voriconazole concentrations after allogeneic hematopoietic stem cell transplantation

Plasma voriconazole concentrations vary considerably between patients receiving standard dosing, and trough voriconazole concentrations are known to affect efficacy and toxicity. Temporal variations in serial plasma voriconazole concentrations through the course of therapy in hematopoietic stem cell transplantation patients has not been carefully described. Paired voriconazole concentrations in 64 patients were studied to determine the predictability of the second concentration based on the first. The difference between the two values was < or = 5% in six patients. In 25 patients, the second concentration was higher by a median of 40%. In 33 patients, the subsequent concentration was lower by a median of 59%. For patients with an initial concentration of < 2 microg/ml, the correlation between the two values was poor (r = 0.24; P < 0.17). For those with an initial concentration of > or = 2 microg/ml, the correlation was good (r = 0.72; P < 0.0001). There was no relationship between the magnitude of the change and the time elapsing between the two measurements. Among the 43 patients who had an initial concentration of > or = 1 microg/ml, the two voriconazole measurements were strongly correlated (r = 0.66, P < 0.0001), but only 67% had a voriconazole serum concentration of > or = 1 microg/ml on the second measurement. No studied variables were reliable predictors in identifying concentrations above or below 1 or 2 microg/ml. Our data suggest that variations in voriconazole concentrations are unpredictable despite standard dosing, and the acceptability of a concentration on one occasion cannot be extrapolated to future concentrations in the same patient. This suggests that ongoing therapeutic drug monitoring and dose adjustment may be beneficial in patients requiring prolonged voriconazole therapy.

Therapeutic strategies for invasive fungal infections in neonatal and pediatric patients

Invasive Candida and Aspergillus infections are the most commonly encountered fungal infections. They appear to be life threatening in the setting of profound immunosuppression, whereas cases that are resistant to antifungal therapy are occasionally encountered. Novel antifungal triazole and echinocandin agents appear to exhibit good activity as first-line or salvage therapy, whereas the use of amphotericin B formulations is particularly valuable in neonates. Significant differences in toxicity have been demonstrated among various antifungal agents with in vitro activity from available comparative data on fungal infections in children: however, no clear difference in treatment efficacy has been demonstrated. However, very little data are available about neonates. Host factors and responsible fungal species most frequently guide the choice of therapy.

Pinpointing prognostic indicators of fungal infections in transplant patients

A number of advances have been made in the prevention and treatment of invasive fungal infections (IFIs) in transplant recipients. However, despite best clinical efforts, patient outcomes are often disappointing. The study of prognostic indicators of IFI for transplant patients may aid in the development of improved prevention measures, or determine more aggressive treatment pathways. Owing to the rarity of IFI, appropriately powered studies are often difficult to achieve; moreover, a lack of standardized outcome definitions make study comparisons difficult. Herein, prognostic indicators for mortality in transplant patients with IFI are reviewed, with a focus on invasive aspergillosis and invasive candidiasis

Clinical indications for newer antifungal agents

Recent years have seen the release of multiple new systemic antifungal agents, significantly increasing options for the treatment of most serious fungal infections. Newly available drugs include those in the echinocandin class, including caspofungin, micafungin, and anidulafungin, as well as the newer generation triazoles, voriconazole and posaconazole. Ordering of these agents is variably restricted, depending on a given institution's policies, and all are costly. In this review we examine the available evidence and outline the role of newer antifungal medications in several common and/or important situations, including invasive and mucocutaneous Candida infection, febrile neutropenia, invasive aspergillosis, zygomycosis, and endemic mycoses.

Bronchopulmonary disposition of micafungin in healthy adult volunteers

By way of bronchoscopy and bronchoalveolar lavage, intrapulmonary steady-state concentrations of micafungin administered at 150 mg daily to 15 healthy volunteers were determined at 4, 12, and 24 h after the third dose. The micafungin disposition was predominantly intracellular, with approximately 106% penetration into alveolar macrophages and 5% penetration into epithelial lining fluid.

Breakthrough Aspergillus fumigatus and Candida albicans double infection during caspofungin treatment: laboratory characteristics and implication for susceptibility testing

Caspofungin is used for the treatment of acute invasive candidiasis and as salvage treatment for invasive aspergillosis. We report characteristics of isolates of Candida albicans and Aspergillus fumigatus detected in a patient with breakthrough infection complicating severe gastrointestinal surgery and evaluate the capability of susceptibility methods to identify candin resistance. The susceptibility of C. albicans to caspofungin and anidulafungin was investigated by Etest, microdilution (European Committee on Antibiotic Susceptibility Testing [EUCAST] and CLSI), disk diffusion, agar dilution, and FKS1 sequencing and in a mouse model. Tissue was examined by immunohistochemistry, PCR, and sequencing for the presence of A. fumigatus and resistance mutations. The MICs for the C. albicans isolate were as follows: >32 microg/ml caspofungin and 0.5 microg/ml anidulafungin by Etest, 2 microg/ml caspofungin and 0.125 microg/ml anidulafungin by EUCAST methods, and 1 microg/ml caspofungin and 0.5 microg/ml anidulafungin by CLSI methods. Sequencing of the FKS1 gene revealed a mutation leading to an S645P substitution. Caspofungin and anidulafungin failed to reduce kidney CFU counts in animals inoculated with this isolate (P > 0.05 compared to untreated control animals), while both candins completely sterilized the kidneys in animals infected with a control isolate. Disk diffusion and agar dilution methods clearly separated the two isolates. Immunohistochemistry and sequencing confirmed the presence of A. fumigatus without FSK1 resistance mutations in liver and lung tissues. Breakthrough disseminated aspergillosis and candidiasis developed despite an absence of characteristic FKS1 resistance mutations in the Aspergillus isolates. EUCAST and CLSI methodology did not separate the candin-resistant clinical isolate from the sensitive control isolate as well as did the Etest and agar methods.

Newer antifungal agents for invasive fungal infections in patients with haematological malignancy

Since 2001 five new systemically administered antifungal agents have been approved for clinical use. This represents a major advance for antifungal therapy in haematological malignancy patients undergoing chemotherapy or haematopoietic stem cell transplant (HSCT). The echinocandins are a new class of antifungals with a novel mode of action. Capsofungin has already established itself as a valuable therapy for candidaemia and salvage therapy of invasive aspergillosis. Although both anidulafungin and micafungin are approved for treatment of candidiasis, their role in invasive aspergillosis requires more clinical trial evaluation. Of the two newer triazoles, voriconazole has been recommended in international guidelines as primary therapy for acute invasive aspergillosis. Posaconazole has a broad spectrum of activity in vitro and a potentially key role in antifungal prophylaxis in high-risk HSCT recipients and during prolonged neutropenia. Although some of these drugs have important interactions with other medications, and potential toxicities, they are safer to use and more efficacious than amphotericin B deoxycholate. Their arrival gives more choices to treat rarer mycoses and will facilitate clinical trial assessment of combination therapy of aspergillosis where single agent therapy gives less than 50% success rates.

Therapeutic drug monitoring of voriconazole

Voriconazole is a triazole antifungal developed for the treatment of life-threatening fungal infections in immunocompromised patients. The drug, which is available for both oral and intravenous administration, has broad-spectrum activity against pathogenic yeasts, dimorphic fungi, and opportunistic molds. Voriconazole has a nonlinear pharmacokinetic profile with a wide inter- and intraindividual variety. This variability is caused by many factors such as gender, age, genotypic variation, liver dysfunction, the presence of food, and so on. Another important factor influencing voriconazole's pharmacokinetic profile is drug-drug interactions with CYP450 inhibitors as well as inducers. Variability in plasma concentrations, as a result of the previously mentioned aspects, may lead to variability in efficacy or toxicity. Determination of plasma concentrations is indicated in situations to guide dosing and to individualize and improve the treatment options resulting in better therapeutic outcome or fewer side effects. In this article, we review factors influencing voriconazole pharmacokinetic profile, the data supporting exposure-effect and exposure-toxicity relationships, review the gaps in current knowledge, which make broad recommendations for therapeutic drug monitoring difficult for voriconazole, provide the indications in which therapeutic drug monitoring is reasonable based on currently available data (eg, children), and outline the ways in which this problem could be solved. We provide a summary of the problem so that further research can be conducted to address this are of clinical need.

Evaluation of the disk diffusion method compared to the microdilution method in susceptibility testing of anidulafungin against filamentous fungi

Susceptibility testing of anidulafungin (AFG) against 32 mold isolates showed an excellent correlation between disk diffusion (DD) and broth microdilution methods. Based on our data, a 2-microg disk of AFG and a 24-h reading time might represent the best parameters for AFG DD testing against filamentous fungi.

Breakthrough invasive fungal infection in an immunocompromised host while on posaconazole prophylaxis: an omission in patient counseling and follow-up

Posaconazole (Noxafil ® Schering-Plough Corporation) is a triazole antifungal approved in the United States for the treatment of oropharyngeal candidiasis and for the prophylaxis of Candida and Aspergillus infections in the immunocompromised host. Posaconazole is available only as an oral suspension. When used for the prevention of Candida and Aspergillus infections, posaconazole should be taken three times daily with a high fat meal to maximize oral absorption. Failure to take posaconazole with food will lead to subtherapeutic serum levels and decreased clinical effectiveness of the drug.

We report the case of a 49-year-old woman with acute myeloid leukemia who received 4 months of posaconazole as an outpatient for the labeled indication of prophylaxis of Candida and Aspergillus infections. During her last admission, the patient presented with an invasive sinus infection diagnosed as a mixed Aspergillus and Mucor etiology. The patient succumbed to this infection five weeks after presentation. Upon investigation it was found that the patient did not self-administer posaconazole as required in the product labeling, which may have led to drug failure in this patient. We submit this case to illustrate the importance of patient education regarding proper administration of posaconazole. The important role of the outpatient physician, nurse, and pharmacist in this setting is underscored. J Oncol Pharm Practice (2008) 14: 189—193.

Clinical application of voriconazole concentrations in the treatment of invasive aspergillosis

OBJECTIVE

To review the current literature to determine the clinical application of therapeutic drug monitoring of voriconazole in the treatment of invasive aspergillosis (IA).

DATA SOURCE

A MEDLINE search (1966-June 2008) was performed using the search terms voriconazole, aspergillosis, levels, monitoring, and serum concentration.

STUDY SELECTION AND DATA EXTRACTION

All pertinent English-language literature on voriconazole use in adults was included for evaluation.

DATA SYNTHESIS

IA is a serious fungal infection with a mortality rate of nearly 100% without adequate treatment; current therapeutic options are limited. A clinical trial comparing amphotericin B deoxycholate with voriconazole in treatment of IA found voriconazole to be superior. The use of voriconazole, however, is complicated due to its saturable metabolism, nonlinear kinetic profile, and drug interactions, which result in considerable interpatient variability in concentrations. Therefore, therapeutic monitoring of voriconazole trough concentrations may lead to improved patient outcomes. A recent prospective study on the use of voriconazole for treatment of invasive mycoses demonstrated that 46% of the patients had a lack of response when trough plasma concentrations were less than or equal to 1 microg/mL, compared with 12% of patients with trough concentrations greater than 1 microg/mL (p = 0.02). All patients with low trough concentrations who did not respond to voriconazole improved upon dose escalation. The upper limit of a therapeutic range is based on the presence of adverse events. The most common adverse effects associated with voriconazole are visual disturbances (21%) and elevations in liver transaminase levels (12.4%). Current literature suggests that a greater incidence of adverse effects may be associated with trough concentrations greater than 6 microg/mL.

CONCLUSIONS

A standardized therapeutic range for voriconazole has not been defined. Most available studies recommend trough concentrations of approximately 1-6 microg/mL. Prospective, randomized trials are needed to confirm the correlation between plasma voriconazole concentrations and clinical outcomes.

International interlaboratory proficiency testing program for measurement of azole antifungal plasma concentrations

An international interlaboratory proficiency testing program for the measurement of antifungal drugs was initiated in 2007. This first round was limited to azole antifungals: fluconazole, itraconazole and hydroxyitraconazole, voriconazole, and posaconazole. The results demonstrate the need for and utility of an ongoing proficiency testing program to further improve the analytical methods for routine patient management and clinical research.

Effect of sampling method and incubation temperature on fungal culture in canine sinonasal aspergillosis

OBJECTIVES

To evaluate the most appropriate sampling procedure and the effect of incubation temperature on fungal culture in the diagnosis of canine sinonasal aspergillosis (SNA).

METHODS

Sixteen dogs with SNA and 20 dogs with non-fungal nasal disease entered a prospective study. Nasal secretions and mucosal biopsies were collected in all dogs. Fungal plaques were also sampled in dogs with SNA. Each specimen was taken in duplicate from each dog and incubated at room temperature and 37 degrees C.

RESULTS

In dogs with SNA, nasal secretions, mucosal biopsies and fungal plaques yielded fungal growth at room temperature in one, one and seven dogs, respectively, whereas fungal growth was obtained at 37 degrees C in three, 12 and 14 dogs, respectively. No specimen collected from any dog with non-fungal nasal disease yielded fungal growth at room temperature or at 37 degrees C.

CLINICAL SIGNIFICANCE

The diagnosis of canine SNA is more likely to be confirmed following culture of mucosal biopsies or fungal plaques than nasal secretions sampled blindly with swabs. Incubating cultures at 37 degrees C is more likely to provide a diagnostic outcome than when samples are cultured at room temperature. Fungal culture of nasal specimens has good specificity for the diagnosis of SNA in dogs.

Results from the ARTEMIS DISK Global Antifungal Surveillance Study, 1997 to 2007: 10.5-year analysis of susceptibilities of noncandidal yeast species to fluconazole and voriconazole determined by CLSI standardized disk diffusion testing

Fluconazole in vitro susceptibility test results determined by the CLSI M44-A disk diffusion method for 11,240 isolates of noncandidal yeasts were collected from 134 study sites in 40 countries from June 1997 through December 2007. Data were collected for 8,717 yeast isolates tested with voriconazole from 2001 through 2007. A total of 22 different species/organism groups were isolated, of which Cryptococcus neoformans was the most common (31.2% of all isolates). Overall, Cryptococcus (32.9%), Saccharomyces (11.7%), Trichosporon (10.6%), and Rhodotorula (4.1%) were the most commonly identified genera. The overall percentages of isolates in each category (susceptible, susceptible dose dependent, and resistant) were 78.0%, 9.5%, and 12.5% and 92.7%, 2.3%, and 5.0% for fluconazole and voriconazole, respectively. Less than 30% of fluconazole-resistant isolates of Cryptococcus spp., Cryptococcus albidus, Cryptococcus laurentii, Trichosporon beigelii/Trichosporon cutaneum, Rhodotorula spp., Rhodotorula rubra/Rhodotorula mucilaginosa, and Rhodotorula glutinis remained susceptible to voriconazole. Emerging resistance to fluconazole was documented among isolates of C. neoformans from the Asia-Pacific, Africa/Middle East, and Latin American regions but not among isolates from Europe or North America. This survey documents the continuing broad spectrum of activity of voriconazole against opportunistic yeast pathogens but identifies several of the less common species with decreased azole susceptibility. These organisms may pose a future threat to optimal antifungal therapy and emphasize the importance of prompt and accurate species identification.

Pharmacokinetic Interaction Between Everolimus and Antifungal Triazoles in a Liver Transplant Patient

Objective:

TO describe the management of a pharmacokinetic interaction between azole antifungals (fluconazole and voriconazole) and everolimus in a patient who underwent an orthotopic liver transplant.

Case Summary:

A 65-year-old male who received an orthotopic liver transplant experienced an iatrogenic retroperitoneal duodenal perforation on postoperative day 55. His condition was subsequently complicated by severe sepsis and acute renal failure. Intravenous fluconazole 400 mg, followed by 100 mg every 24 hours according to impaired renal function, was immediately started; to avoid further nephrotoxicity, immunosuppressant therapy was switched from cyclosporine plus mycophenolate mofetil to oral everolimus 0.75 mg every 12 hours. Satisfactory steady-state minimum concentration (Cmin) of everolimus was achieved (∼5 ng/mL). On day 72 posttransplant, because of invasive aspergillosis, antifungal therapy was switched to intravenous voriconazole 400 mg every 12 hours on the first day, followed by 200 mg every 12 hours; to prevent drug toxicity, the everolimus dosage was promptly lowered to 0.25 mg every 24 hours. At that time, the everolimus Cmin averaged approximately 3 ng/mL. The concentration/dose ratio of everolimus (ie, Cmin reached at steady-state for each milligram per kilogram of drug administered) was markedly lower during fluconazole versus voriconazole cotreatment (mean ± SD, 3.49 ± 0.29 vs 11.05 ± 0.81 ng/mL per mg/kg/daily; p < 0.001). Despite intensive care, the patient's condition continued to deteriorate and he died on day 84 posttransplant

Discussion:

Both azole antifungals were considered probable causative agents of an interaction with everolimus according to the Drug Interaction Probability Scale. The Interaction is due to the inhibition of CYP3A4–mediated everolimus clearance. Of note, prompt reduction of the everolimus dosage since the first azole coadministration, coupled with intensive therapeutic drug monitoring, represented a useful strategy to prevent drug overexposure.

Conclusions:

Our data suggest that during everolimus-azole cotreatment, a dose reduction of everolimus is needed to avoid overexposure. According to the different inhibitory potency of CYP3A4 activity, the reduction should be lower during fluconazole than during voriconazole cotreatment.

In vitro activities at pH 5.0 and pH 7.0 and in vivo efficacy of flucytosine against Aspergillus fumigatus

The antifungal agent flucytosine was found to be active in vitro against Aspergillus fumigatus isolates when the MIC was determined at pH 5.0 instead of pH 7.0. The in vitro MIC at pH 5.0 corresponded to the in vivo efficacy of flucytosine monotherapy in a murine model of invasive aspergillosis.

Voriconazole-induced photosensitivity

Voriconazole is a broad-spectrum triazole antifungal agent indicated for invasive aspergillosis, refractory Candida infections, and other emerging invasive fungal infections. Adverse cutaneous reactions associated with voriconazole therapy occur in fewer than 10% of treated patients and range from mild erythematous eruptions to life-threatening reactions such as the Stevens-Johnson syndrome and toxic epidermal necrolysis. Photosensitivity reactions are an uncommon but characteristic dermatitis in voriconazole recipients, particularly following chronic administration. We report a case of voriconazole-induced phototoxicity in a 50-year-old male with Candida parapsilosis endocarditis that reversed on discontinuation of the drug.