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

Efficacy of single-dose liposomal amphotericin B or micafungin prophylaxis in a neutropenic murine model of invasive pulmonary aspergillosis

In a neutropenic murine model of invasive pulmonary aspergillosis, prophylaxis with single doses of liposomal amphotericin B or micafungin at >or=5 mg/kg of body weight improved animal survival and suppressed the lung fungal burden for up to 7 days after infection, demonstrating the potential utility of infrequent dosing with these antifungals.

Incidence of systemic fungal infection and related mortality following severe burns

Advancements in burn care therapy have extended survival of seriously burned patients, exposing burn patients to increased risk of infectious complications, notably fungal infections. We performed a 12-year review of autopsied patients with severe burns for the presence of fungal infection at the US Army Institute of Surgical Research Burn Center between February 1991 and November 2003. The primary goal was to identify the relationship between fungal element noted in autopsy and mortality, and to determine contributing factors that increase a patient's susceptibility to fungal infection. A total of 228 deaths (6.1%) resulted from the 3751 admissions of which 97 underwent autopsy. Fungal elements were identified on histopathology in 44% (43 of 97) of autopsied patients with an attributable mortality of 33% (14 of 43). Aspergillus and Candida were the most frequently recovered fungi, but Aspergillus was recovered in 13 of the 14 cases with fungus identified as an attributable cause of death. The most common sites of infections with attributable mortality were wounds (86%) and the pulmonary system (14%). Total body surface area (TBSA) burn and length of stay (survival after burn) were identified as contributing factors for the incidence of fungal element in autopsy on ROC curve analysis. More severely injured patients with greater %TBSA burn injury and full-thickness burns require a longer recovery period resulting in a longer hospital stay. The propensity for fungal infection increases the longer the wound is present. Therefore, the development of products to close the wound more rapidly, improvement in topical antifungal therapy with mold activity for treating wounds, and implementation of appropriate systemic antifungal therapy may improve outcome for severely injured burn victims susceptible to fungal infections.

Establishing in vitro-in vivo correlations for Aspergillus fumigatus: the challenge of azoles versus echinocandins

Two clinical isolates of Aspergillus fumigatus, designated AT and DK, were recently obtained from patients failing caspofungin and itraconazole therapy, respectively. The isolates were tested by microdilution for susceptibility to itraconazole, voriconazole, posaconazole, ravuconazole, and caspofungin and by Etest for susceptibility to amphotericin B and caspofungin. Susceptibility testing documented that the DK isolate was azole resistant (itraconazole and posaconazole MICs, >4 microg/ml; voriconazole MIC, 2 microg/ml; ravuconazole MIC, 4 microg/ml), and the resistance was confirmed in a hematogenous mouse model, with mortality and the galactomannan index as the primary and secondary end points. Sequencing of the cyp51A gene revealed the M220K mutation, conferring multiazole resistance. The Etest, but not microdilution, suggested that the AT isolate was resistant to caspofungin (MIC, >32 microg/ml). In the animal model, this isolate showed reduced susceptibility to caspofungin. Sequencing of the FKS1 gene revealed no mutations; the enzyme retained full sensitivity in vitro; and investigation of the polysaccharide composition showed that the beta-(1,3)-glucan proportion was unchanged. However, gene expression profiling by Northern blotting and real-time PCR demonstrated that the FKS gene was expressed at a higher level in the AT isolate than in the susceptible control isolate. To our knowledge, this is the first report to document the presence of multiazole-resistant clinical isolates in Denmark and to demonstrate reduced susceptibility to caspofungin in a clinical A. fumigatus isolate with increased expression of the FKS gene. Further research to determine the prevalence of resistance in A. fumigatus worldwide, and to develop easier and reliable tools for the identification of such isolates in routine laboratories, is warranted.

Revised definitions of invasive fungal disease from the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) Consensus Group

BACKGROUND

Invasive fungal diseases are important causes of morbidity and mortality. Clarity and uniformity in defining these infections are important factors in improving the quality of clinical studies. A standard set of definitions strengthens the consistency and reproducibility of such studies.

METHODS

After the introduction of the original European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) Consensus Group definitions, advances in diagnostic technology and the recognition of areas in need of improvement led to a revision of this document. The revision process started with a meeting of participants in 2003, to decide on the process and to draft the proposal. This was followed by several rounds of consultation until a final draft was approved in 2005. This was made available for 6 months to allow public comment, and then the manuscript was prepared and approved.

RESULTS

The revised definitions retain the original classifications of "proven," "probable," and "possible" invasive fungal disease, but the definition of "probable" has been expanded, whereas the scope of the category "possible" has been diminished. The category of proven invasive fungal disease can apply to any patient, regardless of whether the patient is immunocompromised, whereas the probable and possible categories are proposed for immunocompromised patients only.

CONCLUSIONS

These revised definitions of invasive fungal disease are intended to advance clinical and epidemiological research and may serve as a useful model for defining other infections in high-risk patients.

Does pre-exposure of Aspergillus fumigatus to voriconazole or posaconazole in vitro affect its virulence and the in vivo activity of subsequent posaconazole or voriconazole, respectively? A study in a fly model of aspergillosis

OBJECTIVES

Voriconazole and posaconazole are effective as both prophylaxis and treatment for invasive aspergillosis (IA) in immunocompromised patients. Hence, it is important to determine whether Aspergillus pre-exposure to voriconazole or posaconazole diminishes subsequent posaconazole or voriconazole activity, respectively.

METHODS

We used Aspergillus fumigatus (AF) 293 conidia with or without prior exposure to voriconazole or posaconazole [three serial passages on plates containing regular yeast extract-glucose (YAG) media, YAG+0.0625 mg/L voriconazole or YAG+0.025 mg/L posaconazole]. Toll-deficient Drosophila melanogaster flies were infected by injection, and 8 day survival was monitored. Following infection, flies were fed either regular food, food containing 1000 mg/L voriconazole (posaconazole-exposed conidia) or 1000 mg/L posaconazole (voriconazole-exposed conidia). Voriconazole and posaconazole concentrations in flies were confirmed by HPLC.

RESULTS

AF inoculation resulted in 71% mortality 8 days post-infection (median survival 4 days). Prior conidial exposure to voriconazole or posaconazole did not affect mortality (73%, P = 0.8 for voriconazole pre-exposed and 76%, P = 0.49 for posaconazole pre-exposed). Voriconazole treatment post-infection had a protective effect, reducing mortality to 42% (P = 0.0002), while prior conidial exposure to posaconazole did not alter the protective effect of voriconazole (34% 8 day mortality, P = 0.35). Likewise, posaconazole treatment post-infection reduced mortality to 36%, while prior conidial exposure to voriconazole did not alter the protective effect of posaconazole (39% mortality, P = 0.92). Median fly homogenate concentrations of voriconazole and posaconazole were 0.44 and 2.05 mg/L, respectively.

CONCLUSIONS

Prior exposure of AF to voriconazole or posaconazole did not affect the virulence of AF nor the subsequent activity of the alternate triazole in a Drosophila model of IA.

[The role of anidulafungin therapy in solid organ transplant recipients]

Anidulafungin is a new echinocandin recently approved for the treatment of esophageal candidiasis, candidemia and other forms of invasive candidiasis, such as peritonitis and intra-abdominal abscesses in non-neutropenic patients. It is fungicidal against Candida spp. and fungistatic against Aspergillus spp. It is active against Pneumocystis jirovecii. In contrast, anidulafungin does not have activity against Cryptococcus neoformans, Zygomycetes or molds, other than Aspergillus spp. The drug is well tolerated, even in patients with renal or hepatic impairment. In contrast to other echinocandins, it does not significantly interfere with the cytochrome P450 pathway and has a low drug-drug interaction profile, including calcineurinic agents and other drugs used in transplant recipients. So far, anidulafungin appears to have an excellent safety profile with few adverse events and it promises a special consideration in the management of fungal infections happening in transplant recipients.

[Candidates for virulence factors of Aspergillus fumigatus]

The number of patients with invasive fungal infection (IFI) has dramatically increased since the beginning of the 1980s. Aspergillus fumigatus, the most common species recovered from aspergillosis, is an important pathogen of IFI. Recently, new antifungal agents have become available in Japan, but mortality from aspergillosis is still high. Early initiation of therapy seems to improve the survival rate. Study of virulence factors of the fungus may lead to the development of novel diagnostic tools or advancements in therapy. Many candidates of the fungal virulence factors have been studied including proteases and mycotoxins. We previously discussed the influence of fungal secondary metabolites such as gliotoxin and other low molecular components on the virulence, and showed that A. fumigatus produces potent cytotoxic substances other than gliotoxin. Studies are in progress to clarify the significance of the unknown substances.