Epidemiology and outcome of zygomycosis: a review of 929 reported cases

Pulmonary dysfunction in pediatric hematopoietic stem cell transplant patients: overview, diagnostic considerations, and infectious complications

Pulmonary complications are among the most common and serious sequelae seen in hematopoietic stem cell transplantation (HSCT) recipients. This two-part review addresses the incidence and impact of pulmonary complications in pediatric HSCT patients. In this first part we review the available data for the use of diagnostic modalities in this population, including flexible bronchoscopy with bronchoalveolar lavage (BAL) and open lung biopsy (OLB). We also review the many infectious pulmonary complications that may occur in pediatric HSCT recipients, utilizing the traditional chronologic divisions of neutropenic phase (0-30 days following HSCT), early phase (30-100 days), and late phase (>100 days).

Early use of posaconazole in the successful treatment of rhino-orbital mucormycosis caused by Rhizopus oryzae

Mucormycosis is a potentially fatal, rapidly destructive, opportunistic infection often seen in immunocompromsied individuals and patients with diabetes mellitus. We describe two patients with rhino-orbital mucormycosis caused by Rhizopus oryzae who received posaconazole within 7 days of diagnosis and in whom cure was achieved in conjunction with extensive surgical resection of diseased tissue. Posaconazole was well-tolerated. Our experience indicates that this new extended-spectrum azole antifungal agent can be used early in the course of zygomycete infection with good results.

Antimicrobial resistance prevention initiative--an update: proceedings of an expert panel on resistance

Antimicrobial resistance is a growing problem that complicates the treatment of important nosocomial and community-acquired infections. It is a worldwide problem that spans the range of human pathogens, including bacteria, fungi, and viruses. This update from the Antimicrobial Resistance Prevention Initiative (ARPI) provides a review of some important trends in antibiotic, antifungal, and antiviral resistance. Areas of focus include multidrug-resistant bacteria in the hospital setting; the growing problem of community-acquired methicillin-resistant Staphylococcus aureus; triazole and polyene resistance in nosocomial infections caused by non-Candida albicans or Aspergillus species, and the utility of in vitro susceptibility testing for these fungal infections; antiviral resistance in alpha- or beta-herpesviruses causing genital herpes or cytomegalovirus infection in immunocompromised hosts; and concerns about a possible pandemic involving avian influenza A and the importance of minimizing emergence of resistant strains of this highly pathogenic virus. The challenges in each area are different, but the general keys to addressing the growing problem of antimicrobial resistance continue to be responsible antimicrobial stewardship and the development of newer antimicrobial agents.

Two cases of hepatic zygomycosis in allogeneic stem cell transplant recipients and review of literature

Gastrointestinal zygomycosis is a rare condition with a high mortality rate. We present 2 fatal cases of hepatic zygomycosis following allogeneic hematopoietic stem cell transplantation and review the literature.

Breakthrough fungal infections after allogeneic hematopoietic stem cell transplantation in patients on prophylactic voriconazole

Seventy-one allograft recipients receiving voriconazole, in whom complete clinical, microbiologic and pharmacokinetic data were available, were studied to determine the efficacy of voriconazole in preventing fungal infections. The length of voriconazole therapy was 6-956 days (median 133). The total number of patient-days on voriconazole was 13 805 ( approximately 38 years). A total of 10 fungal infections were seen in patients on voriconazole (18% actuarial probability at 1 year): Candida glabrata (n=5), Candida krusei (n=1), Cunninghamella (n=1), Rhizopus (n=2) and Mucor (n=1). Two of the four zygomycosis cases were preceded by short durations of voriconazole therapy, but prolonged itraconazole prophylaxis. The plasma steady-state trough voriconazole levels around the time the infection occurred were <0.2, <0.2, 0.33, 0.55, 0.63 and 1.78 microg/ml in the six candidiasis cases. Excluding the four zygomycosis cases, all the six candidiasis cases were seen among the 43 patients with voriconazole levels of < or =2 microg/ml and none among the 24 with levels of >2 microg/ml (P=0.061). We conclude that voriconazole is effective at preventing aspergillosis. However, breakthrough zygomycosis is seen in a small proportion of patients. The role of therapeutic voriconazole monitoring with dose adjustment to avoid breakthrough infections with fungi that are otherwise susceptible to the drug needs to be explored prospectively.

Posaconazole: a new broad-spectrum antifungal agent

The rising incidence of invasive fungal infections and the emergence of broader fungal resistance have led to the need for novel antifungal agents. Posaconazole is a new member of the triazole class of antifungals. It is available as an oral suspension and has a favorable toxicity profile, has demonstrated clinical efficacy in the treatment of oropharyngeal candidiasis and has shown promise as salvage therapy for invasive aspergillosis, zygomycosis, cryptococcal meningitis and a variety of other fungal infections. In addition, data from randomized controlled studies support its efficacy for use in prophylaxis of invasive fungal infections in patients who are severely immunocompromised. The wide spectrum activity of posaconazole in in vitro studies, animal models and preliminary clinical studies suggest that posaconazole represents an important addition to the antifungal armamentarium.

Rhizopus microsporus var. rhizopodiformis sinus-orbital zygomycosis in an immunosuppressed patient: successful treatment with posaconazole after a complicated clinical course

A case of sinus-orbital Rhizopus microsporus var. rhizopodiformis infection in a patient with graft versus host disease following allogeneic blood stem cell transplantation is reported. Commercially available pea straw compost used for gardening was suspected to be the source of the infection. After an initial relapse, treatment with surgical debridement, liposomal amphotericin B and posaconazole was successful.

Zygomycosis: an uncommon cause for peripheral facial palsy in diabetes

Mucormycosis is an emerging fungal infection with a high rate of mortality. Diabetic and immuno-compromised patients are the most frequent hosts. We report a case of rhino-orbito-cerebral mucormycosis revealed by facial palsy in a diabetic, immuno-compromised patient with difficult life conditions. He received intravenous antifungal treatment (amphotericin B) and early surgical debridement and completely recovered with no recurrence after 3 months of follow-up. Physicians should be aware of such atypical clinical presentations due to the need for early appropriate combined medical and surgical management to improve disease recovery and prognosis.

Zygomycosis ? current epidemiological aspects

Zygomycoses are very rare invasive fungal infections (IFI). They primarily occur in the immunocompromised patients and are associated with a high mortality. During the last years, a rising incidence of zygomycosis in patients undergoing allogeneic haematopoietic stem cell transplantation (HSCT) has been reported, which is probably a part of the trend in the incidence of mould infections that has been going on for decades. Difficulty in diagnosis, especially concerning the differentiation of zygomycosis from the far more common aspergillosis, additionally hampers a reliable assessment of the incidence of zygomycosis. In patients undergoing allogeneic HSCT, changes in the frequency, severity and management of Graft-versus-Host-Disease (GvHD) also favour mould infections, among them zygomycosis. In centres employing voriconazole for prophylaxis of IFI since its approval for treatment in 2001, incidence of aspergillosis has markedly dropped. The assumption that the frequency of zygomycosis has increased since the introduction of voriconazole is not found in prospective trials and therefore needs verification, especially when considering the long ongoing trends in fungal incidence. Currently recruiting multicentre trials on primary prophylaxis of IFI will have to show the preventive effectiveness of antifungals with mould activity and the incidence of zygomycosis under prospectively controlled conditions.

In vitro susceptibilities of 217 clinical isolates of zygomycetes to conventional and new antifungal agents

We evaluated the in vitro susceptibilities of 217 zygomycetes to amphotericin B, ketoconazole, fluconazole, itraconazole, voriconazole, posaconazole, caspofungin, and flucytosine. The significant in vitro activity of posaconazole against several species appears to support its reported clinical efficacy. Decreased susceptibility to amphotericin B was noted with Cunninghamella bertholletiae.

Characterization of an extracellular subtilisin protease of Rhizopus microsporus and evidence for its expression during invasive rhinoorbital mycosis

An endoprotease Arp (alkaline Rhizopus protease) was identified and purified to virtual homogeneity from the culture supernatant of an isolate of Rhizopus microsporus var. rhizopodiformis recovered from a non-fatal case of rhinoorbital mucormycosis. N-terminal sequencing of the mature native enzyme was obtained for the first 20 amino acids and revealed high homology to serine proteases of the subtilisin subfamily. Arp migrated in SDS-PAGE with an estimated molecular mass of 33 kDa and had a pI determined to be at pH 8.8. Arp is proteolytically active against various substrates, including elastin, over a broad pH range between 6 and 12 with an optimum at pH 10.5. After invasive mucormycosis, specific antibodies against Arp were detected in stored serum samples taken from the patient from whom the R. microsporus strain of this study had been isolated. Furthermore, in search of factors involved in thrombosis as a typical complication of mucormycosis, a procoagulatory effect of the enzyme has recently been shown. Altogether, these data substantiate the expression of Arp during human rhinoorbital mucormycosis and suggest a role of the enzyme in pathogenesis.

Pneumopathie à Cunninghamella bertholletiae compliquant une leucémie aigüe lymphoblastique

Pulmonary mucormycosis occur in immunosuppressed patients with a neutropenic treatment or a malignant neoplasia. Although the histological study alone cannot enable species identification, the pathologist usually makes the diagnosis of mucormycosis and can eliminate other filamentous mycoses such as aspergillosis or scedosporiosis. Pulmonary infection caused by Cunninghamella bertholletiae is a very rare lung mucormycosis, particularly in young patients. The histological features of this filamentous mycosis are unusual making the diagnosis of mucormycosis difficult. Mycological study is then crucial for the diagnosis. We report a case of a pulmonary infection caused by Cunninghamella bertholletiae occurring in a young girl with acute lymphoblastic leukemia.

Combination antifungal therapy: the new frontier

The past decade has seen a significant increase in the incidence of invasive fungal infections. The antifungal armamentarium for the treatment of serious fungal infections remains limited. A possible approach to overcoming antifungal drug resistance and high mortality rates seen in severe fungal infections is to combine two or three classes of antifungals, especially if the drugs have different mechanisms of action. Combinations of new agents along with more traditional antifungals have now been shown to possess some synergistic or at least additive activity against many fungi in in vitro and animal studies. On the other hand, caution is still needed since some antifungal combinations have also demonstrated antagonistic activity. Well-controlled clinical trials are still required to define the most efficacious antifungal regimen. Furthermore, these trials should also evaluate the side-effect potential of combination regimens and the pharmacoeconomic impact these regimens may have.

Successful treatment of disseminated mucormycosis with a combination of liposomal amphotericin B and posaconazole in a patient with acute myeloid leukaemia

The combination of resection of infected tissue and antifungal therapy is the treatment of choice in mucormycosis. In disseminated mucormycosis, where surgery is impossible, the mortality is almost 90%. We report the first case of disseminated mucormycosis that was cured with a combination therapy of liposomal amphotericin B and posaconazole without surgical intervention.

Posaconazole treatment for Apophysomyces elegans rhino-orbital zygomycosis following trauma for a male with well-controlled diabetes

We report a case of rhino-orbital zygomycosis in a 43-year-old male with well-controlled diabetes mellitus. The patient initially received liposomal amphotericin B, but the infection continued to progress, so posaconazole treatment was begun and eventually led to the cure of his infection. The causative agent was identified as Apophysomyces elegans, an emerging cause of zygomycosis in immunocompetent hosts.

Decrease in the number of reported cases of zygomycosis among patients with diabetes mellitus: a hypothesis

The number of reported cases of zygomycosis in patients with diabetes mellitus in developed countries has decreased since the 1990s, despite the rapid increase in the prevalence of diabetic patients in the Western world. Although prospective population-based studies need to better document this phenomenon, which may have a complex explanation, here I propose the hypothesis that widespread use of statins in patients with diabetes underlies such a trend. Statins have been shown to direct inhibitory activity against a range of Zygomycetes molds, both in vitro and in vivo.

Carbon assimilation profiles as a tool for identification of zygomycetes

Identification of Zygomycetes is difficult and time-consuming by standard microbiological procedures. Carbon assimilation profiles are commonly used for yeast-and bacterial-species identification but rarely for filamentous-fungus identification. Carbon assimilation profiles were evaluated using the commercialized kits ID32C and API 50 CH, which contain 31 and 49 tests, respectively, to serve as simple tools for species identification of Zygomycetes in clinical microbiology laboratories. Fifty-seven strains belonging to 15 species and varieties of Zygomycetes, including Rhizopus, Absidia, Mucor, and Rhizomucor species, were tested for intra- and interspecies variability based on their carbon assimilation profiles. Using ID32C strips, 6 tests were always positive, 7 were never positive, and 18 showed consistently different results between species. With API 50 CH strips, 15 tests were positive for all species, 13 were never positive, and 21 showed different results between species. Nevertheless, assimilation patterns were highly variable among Rhizopus oryzae isolates, and it was not possible to define a specific carbon assimilation profile. With both ID32C and API CH 50 strips, intraspecies variation was found to be low, while large differences were found between genera and species. The clustering of isolates based on their carbon assimilation profiles was in accordance with DNA-based phylogeny of Zygomycetes. In conclusion, carbon assimilation profiles allowed precise and accurate identification of most Zygomycetes to the species level.

Breakthrough zygomycosis after voriconazole administration among patients with hematologic malignancies who receive hematopoietic stem-cell transplants or intensive chemotherapy

Zygomycosis is increasingly reported as a cause of life-threatening fungal infections. A higher proportion of cases reported over the last decades have been in cancer patients, with or without hematopoietic stem cell transplantation (HSCT). The new anti-fungal agent voriconazole is a recently identified risk factor for developing zygomycosis. We reviewed the clinical characteristics and outcomes of a large cohort of cancer patients who developed zygomycosis after exposure to voriconazole. Health care professionals at 13 large cancer centers provided clinical information on cancer patients with zygomycosis and prior exposure to voriconazole. Criteria for inclusion were 5 days or more of voriconazole use and diagnostic confirmation with tissue or histology. Fifty-eight cases were identified among patients with hematologic malignancies, 62% including patients who underwent a HSCT procedure. Fifty-six patients received voriconazole for primary or secondary prophylaxis against fungal infection. In addition to prior exposure to voriconazole, patients also had several of the previously established risk factors for zygomycosis. Amphotericin B was the most commonly prescribed anti-fungal therapy. Overall mortality was 73%. We conclude that zygomycosis after exposure to voriconazole is a recently described entity that is frequently fatal, despite treatment with currently available anti-fungal agents and surgery.

Invasive zygomycosis: update on pathogenesis, clinical manifestations, and management

Zygomycosis is an increasingly common infection in immunocompromised patients. Advances in the understanding of Zygomycetes pathobiology and the introduction of new drugs with improved activity and tolerability for treatment of zygomycosis have improved the prospects of effectively controlling this devastating infection. Further reductions in mortality will require improved diagnostic and novel therapeutic approaches for this group of aggressive opportunistic molds.

Posaconazole as Salvage Therapy in a Patient with Disseminated Zygomycosis: Case Report and Review of the Literature

Zygomycosis refers to any fungal infection originating from the class Zygomycetes and the order Mucorales. In immunocompromised patients, these fungi produce a relatively rapid, violently destructive, and highly fatal infection. Treatment approaches include both aggressive antifungal pharmacotherapy and surgical intervention. Unfortunately, even with optimal therapy, morbidity and mortality rates remain relatively high. As failure rates are elevated with commercial antifungals, new treatment options are needed. Posaconazole is an orally available, extended-spectrum triazole antifungal being investigated in phase III clinical trials for the treatment and prevention of invasive fungal infections, including zygomycosis. We report the case of a 26-year-old Vietnamese man with a medical history of acute lymphocytic leukemia who had undergone consolidation chemotherapy and had neutropenic fever when he came to the emergency department. The patient was admitted to the hospital and treated with broad-spectrum antibiotics and caspofungin. Two weeks into his admission, however, abscesses in the pelvis, prostate, and musculature surrounding the hip were detected radiographically; these abscesses eventually cultured for Mucor sp. Disseminated zygomycosis was diagnosed. Caspofungin was immediately discontinued, and high-dose liposomal amphotericin B 10 mg/kg/day was begun. Over the next month, infection spread to the right lung, left kidney, middle thoracic spine, and epidural space. As a result, oral posaconazole 200 mg 4 times/day was added to the liposomal amphotericin B. Significant clinical, hematologic, mycologic, and radiologic improvements were demonstrated as early as 10 days after start of posaconazole therapy and continued through 41 days of inpatient treatment. Liposomal amphotericin B was discontinued after 3 weeks of posaconazole, and the patient was discharged on hospital day 92 receiving oral posaconazole, with no major adverse events reported. Five months after discharge, the patient had no evidence of fungal disease recurrence or progression. Posaconazole appears to be a well-tolerated and effective salvage treatment for zygomycosis, including disseminated disease.

Multidrug-resistant endosymbiotic bacteria account for the emergence of zygomycosis: A hypothesis

Although the extensive use of Aspergillus-active antifungals has been recently associated with an increase in zygomycosis in several cancer centers, the frequency of this opportunistic mycosis began to rise earlier, since the mid 1990s. The reasons for that emergence are unclear. Recent evidence suggests that endosymbiotic bacteria of Rhizopus species produce toxins that enhance fungal pathogenicity. We postulate that, although Zygomycetes appear equally ubiquitous and virulent to Aspergillus, zygomycosis was rare in the past in immunosuppressed patients specifically because of the widespread use of antibacterials in this patient population. Such use may have resulted in inhibition of endosymbiotic, toxin-producing bacteria and led indirectly in attenuation of Zygomycetes virulence. Thus, the growing rates of antimicrobial resistance over the past decade selected for multidrug-resistant endosymbiotic bacteria of Zygomycetes, which could facilitate the emergence of zygomycosis. This hypothesis, if true, will be the first paradigm of modulation of virulence of opportunistic fungi by antibacterials.

Posaconazole vs. fluconazole or itraconazole prophylaxis in patients with neutropenia

BACKGROUND

Patients with neutropenia resulting from chemotherapy for acute myelogenous leukemia or the myelodysplastic syndrome are at high risk for difficult-to-treat and often fatal invasive fungal infections.

METHODS

In this randomized, multicenter study involving evaluators who were unaware of treatment assignments, we compared the efficacy and safety of posaconazole with those of fluconazole or itraconazole as prophylaxis for patients with prolonged neutropenia. Patients received prophylaxis with each cycle of chemotherapy until recovery from neutropenia and complete remission, until occurrence of an invasive fungal infection, or for up to 12 weeks, whichever came first. We compared the incidence of proven or probable invasive fungal infections during treatment (the primary end point) between the posaconazole and fluconazole or itraconazole groups; death from any cause and time to death were secondary end points.

RESULTS

A total of 304 patients were randomly assigned to receive posaconazole, and 298 patients were randomly assigned to receive fluconazole (240) or itraconazole (58). Proven or probable invasive fungal infections were reported in 7 patients (2%) in the posaconazole group and 25 patients (8%) in the fluconazole or itraconazole group (absolute reduction in the posaconazole group, -6%; 95% confidence interval, -9.7 to -2.5%; P<0.001), fulfilling statistical criteria for superiority. Significantly fewer patients in the posaconazole group had invasive aspergillosis (2 [1%] vs. 20 [7%], P<0.001). Survival was significantly longer among recipients of posaconazole than among recipients of fluconazole or itraconazole (P=0.04). Serious adverse events possibly or probably related to treatment were reported by 19 patients (6%) in the posaconazole group and 6 patients (2%) in the fluconazole or itraconazole group (P=0.01). The most common treatment-related adverse events in both groups were gastrointestinal tract disturbances.

CONCLUSIONS

In patients undergoing chemotherapy for acute myelogenous leukemia or the myelodysplastic syndrome, posaconazole prevented invasive fungal infections more effectively than did either fluconazole or itraconazole and improved overall survival. There were more serious adverse events possibly or probably related to treatment in the posaconazole group. (ClinicalTrials.gov number, NCT00044486 [ClinicalTrials.gov].).

Gastrointestinal zygomycosis caused by Mucor indicus in a patient with acute traumatic brain injury

We report a gastrointestinal infection caused by Mucor indicus in a patient with severe head injuries. Monotherapy with high-dose liposomal amphotericin B successfully eradicated the mucormycosis. Nevertheless, subsequently a hemicolectomy was necessary due to recurrent bleeding from a deep ulcer. Mucor indicus is an uncommon fungal pathogen, typically found in starters used for food fermentation. Reviewing other reports on Mucor indicus infections, primary gastrointestinal manifestations seem to be typical and indicate an oral route of infection.

Contemporary Treatment and Outcomes of Zygomycosis in a Non-oncologic Tertiary Care Center

BACKGROUND

Zygomycosis is an emerging mycosis of increasing relevance. Limited data exist for outcomes with contemporary therapies.

METHODS

A 6-year retrospective chart review was performed in a non-oncological tertiary care center for patients with zygomycosis.

RESULTS

Sixteen episodes of proven (EORTC/MSG criteria) zygomycosis were identified. The average age was 49.2 years. Sites of infection were surgical/traumatic wound [5], rhinocerebral [4], disseminated [2], pulmonary [2], peritoneal [2], and localized skin [1]. Associated conditions included diabetes [7], ketoacidosis [2], end-stage renal disease [4], surgery/trauma [4], steroids [3], solid organ transplant [2], neutropenia [1], and intravenous drug use [1]. Twelve patients had surgical debridement. Medical therapy included liposomal amphotericin B, conventional amphotericin B (CAB), and amphotericin B lipid complex. Overall mortality was 4/16 (25%), occurring in a patient each with rhinocerebral, pulmonary, surgical wound infection, and disseminated disease. Mortality with surgical treatment was 2/12 (17%) vs. 2/4 (50%) without surgery. Mortality for patients treated with CAB was 1/3 vs. 3/12 for those treated with any lipid preparation. Serious morbidity occurred in 7/12 survivors.

CONCLUSIONS

In this limited study of contemporary therapies, patients with zygomycosis from a non-oncological tertiary care center have lower mortality than classically described. This disease and its treatments are still associated with severe morbidity, disfigurement, and disability.

Successful treatment of cutaneous and subcutaneous zygomycosis in an immunosuppressed patient with aplastic anaemia

Zygomycosis in patients with persistent neutropenia had been associated with poor outcomes despite aggressive surgical and antifungal therapy. We describe the case of a 10-year-old girl with aplastic anaemia and persistent neutropenia who developed cutaneous and subcutaneous zygomycosis of her right thigh that was successfully treated with extensive surgical debridement, intravenous liposomal amphotericin B, later changed to oral posaconazole for long-term suppressive therapy and granulocyte colony stimulating factor.

Nosocomial fungal infections: epidemiology, diagnosis, and treatment

Invasive fungal infections are increasingly common in the nosocomial setting. Furthermore, because risk factors for these infections continue to increase in frequency, it is likely that nosocomial fungal infections will continue to increase in frequency in the coming decades. The predominant nosocomial fungal pathogens include Candida spp., Aspergillus spp., Mucorales, Fusarium spp., and other molds, including Scedosporium spp. These infections are difficult to diagnose and cause high morbidity and mortality despite antifungal therapy. Early initiation of effective antifungal therapy and reversal of underlying host defects remain the cornerstones of treatment for nosocomial fungal infections. In recent years, new antifungal agents have become available, resulting in a change in standard of care for many of these infections. Nevertheless, the mortality of nosocomial fungal infections remains high, and new therapeutic and preventative strategies are needed.

Trends in the Epidemiology of Invasive Fungal Infections

Invasive fungal infections have increased in importance, largely because of the increasing size of the population at risk. Candida species remain the fourth most important cause of hospital-acquired bloodstream infections. Infections with Candida species other than C. albicans appear to have become more common, but significant geographic variation has been reported. Invasive aspergillosis and other mould infections are a leading cause of infection-related death in hematopoietic stem cell transplant recipients. Although Aspergillus fumigatus remains the most frequent cause of infection, A. terreus has emerged as an important pathogen, at least among certain populations. Despite marked reductions in the rates of AIDS-associated fungal infections, such as cryptococcosis, in the United States and other developed countries, the burden of these diseases in developing countries is large and increasing. Enhanced surveillance and reporting will be critical to improve our understanding of the importance of invasive fungal infections, to enable prioritization of research and prevention efforts, and to evaluate prevention strategies.

Changing Epidemiology of Rare Mould Infections

There has been an increase in rare mould infections in recent decades. These infections have been reported primarily in severely immunocompromised patients. The emergence of these organisms is multifactorial and can be related to more intense immunosuppression, the prolonged survival of patients who have what were previously fatal diseases, and the selective pressure of broad spectrum antifungal agents used for prophylaxis or therapy. Among these rare mould infections, the Zygomycetes are the most commonly encountered, and in some institutions the increase in these organisms appears to be associated with the use of voriconazole. Aspergillus terreus, a species that is resistant to amphotericin B, and less frequently, A. ustus and A. lentulus, have been noted increasingly as causes of invasive aspergillosis in tertiary care centres in the US. Several species of Scedosporium with innate resistance to many antifungal agents have emerged as major causes of disseminated mould infections that are frequently very difficult to treat. Among patients who have haematological malignancies, are neutropenic or have received a haematopoietic stem cell transplant, infections due to Fusarium species respond poorly to many antifungal agents. Dematiaceous, or brown-black, fungi, most often associated with chronic localised infections, are now increasingly reported as a cause of disseminated infection in immunosuppressed hosts. Concomitant with the increased number of infections with these rare moulds, several new mould-active antifungal agents have been developed. The new expanded spectrum azole, voriconazole, has changed our approach to moulds such as S.apiospermum, Fusarium species and A. terreus that are amphotericin B resistant. Posaconazole, the most recently approved expanded spectrum azole, is the first drug in the azole class to show activity against the Zygomycetes and has proven extremely useful for step-down therapy after initial treatment with amphotericin B. It is not known whether posaconazole is effective as primary therapy for zygomycosis; the use of this agent for that purpose awaits clinical trials with the recently developed intravenous formulation of posaconazole.

Is there a role for polyenes in treating invasive mycoses?

PURPOSE OF REVIEW

This is a clinical review on the current role of polyene antifungals in the treatment of invasive fungal infections. It is timely and relevant because the number of new antifungals being developed has never been greater than today. In addition to re-examining the landmark clinical trials of the past, the more recent findings are put into perspective. The past year has been particularly rich in clinical trials.

RECENT FINDINGS

The main topics of this review are invasive candidiasis, invasive aspergillosis, and the so-called rare fungal infections: zygomycosis, fusariosis, cryptococcosis and histoplasmosis.

SUMMARY

Practical implications of the recent developments are the almost complete replacement of amphotericin B deoxycholate by lipid-based formulations; antifungal efficacy without compromising safety; and treatment choices for infections previously considered untreatable.

Issues Related to the Design and Interpretation of Clinical Trials of Salvage Therapy for Invasive Mold Infection

Invasive mold infection is a major cause of morbidity and mortality among severely immunocompromised individuals. We discuss the challenges involved in the design and interpretation of salvage antifungal trials, focusing on mold infection. We suggest that patients with refractory fungal infection be analyzed separately from those with intolerance to standard regimens because of the poorer prognosis of the former group. We propose a composite outcome assessment in which refractory infection is defined as infection associated with the worsening of at least 2 of the following 3 types of criteria: clinical, radiologic, and mycologic. Confounding variables, including heterogeneity in host factors, initial antifungal therapy, and selection bias, are discussed. Although randomized studies would provide the most credible results, the lack of an adequate number of patients to meet prespecified stratification criteria for all confounding variables makes such studies impractical. Given that randomized studies are unrealistic, studies involving carefully selected, matched, contemporaneous control subjects are likely to be the most useful alternative.

Meningoencephalitis in an adult cow due to Mortierella woifli

A 7-year-old dairy cow presented with clinical signs of neurologic disease. Despite treatment with penicillin, the cow died 36 hours after initial presentation. Necropsy examination revealed multiple foci of hemorrhage within the cerebrum and thickened meninges. Additionally, endometritis and consolidation of approximately 30% of both lungs was observed. Histology revealed necrotizing vasculitis, infarction, and hemorrhage within sections of the brain, uterus, and lung. Large numbers of intralesional fungal hyphae were visible. Because only formalin-fixed tissue was available, polymerase chain reaction was used to make an etiologic diagnosis of Mortierella wolfii.

Mucor circinelloides was identified by molecular methods as a cause of primary cutaneous zygomycosis

A case of primary cutaneous zygomycosis caused by Mucor circinelloides is described. Histopathology showed typical hyphae along with chlamydospores. The isolate was identified by molecular and phenotypic methods. The utility of sequence analysis of the internal transcribed spacer region is highlighted; however, further studies are needed to assess species genetic heterogeneity.

Posaconazole prophylaxis in experimental systemic zygomycosis

Three isolates of zygomycetes belonging to two different genera (Rhizopus oryzae and Absidia corymbifera) were used to produce a systemic infection in neutropenic mice. On days -2 and -1 and at 2 h prior to infection, the mice received either posaconazole (POS) at doses ranging from 20 to 80 mg/kg of body weight/day or amphotericin B (AMB) at 1 mg/kg/day. Antifungal drug efficacy was assessed by determination of the prolongation of survival, determination of the percentage of infected organs (brain, lung, spleen, and kidney), and histological examination for the number of infection foci and their sizes in brain and kidney tissues. AMB significantly prolonged the survival of mice infected with all isolates. POS significantly prolonged the survival of mice infected with zygomycetes. Cultured organs from mice infected with R. oryzae were all positive, while treated mice challenged with A. corymbifera generally showed lower percentages of infected organs compared with the percentages for the controls. Zygomycete isolates established an active infection (the presence of hyphae) in the brains and the kidneys of all controls. In mice challenged with R. oryzae, both antifungal drugs were effective at reducing the number and the size of infection foci in the kidneys. Only AMB reduced the numbers, but not the sizes, of infection foci in the brain. Finally, both drugs significantly reduced the numbers and the sizes of infection foci in both tissues of mice infected with A. corymbifera. Our data suggest that prophylaxis with POS has some potential to prevent zygomycosis.

Molecular basis for enhanced activity of posaconazole against Absidia corymbifera and Rhizopus oryzae

Posaconazole and itraconazole were more potent inhibitors of ergosterol synthesis, in both intact cells and cell extracts from Absidia corymbifera and Rhizopus oryzae, than voriconazole and fluconazole. Similarly, expression of CYP51 from R. oryzae in Saccharomyces cerevisiae significantly increased resistance to fluconazole and voriconazole but not to posaconazole and itraconazole.

Clinical efficacy of new antifungal agents

Several new options are now available for treating serious fungal infections. All three echinocandin agents currently available have been shown in randomized, blinded clinical trials to be efficacious in treating candidemia and invasive candidiasis. By contrast, the demonstrated efficacy of the echinocandins for the treatment of invasive aspergillosis has been based on historically controlled salvage treatment trials in patients failing or intolerant of other therapies. The new triazole agents, voriconazole and posaconazole, have a broad spectrum of antifungal activity. Voriconazole has become the agent of choice for invasive aspergillosis. On the basis of compassionate treatment data, posaconazole appears to be effective for treatment of zygomycosis. These agents have also been shown to be effective in the treatment of non-Aspergillus mould infections, several of the endemic mycoses and serious Candida infections.

Review of Epidemiology, Diagnosis, and Treatment of Invasive Mould Infections in Allogeneic Hematopoietic Stem Cell Transplant Recipients

Invasive mould infections are a major cause of morbidity and mortality in hematopoietic stem cell transplant recipients (HSCT). Allogeneic HSCT recipients are at substantially higher risk than autologous HSCT recipients. Although neutropenia following the conditioning regimen remains an important risk factor for opportunistic fungal infections, most cases of invasive mould infection in allogeneic HSCT recipients occur after neutrophil recovery in the setting of potent immunosuppressive therapy for graft-versus-host disease. Invasive aspergillosis is the most common mould infection. However, there has been an increased incidence of less common non-Aspergillus moulds that include zygomycetes, Fusarium sp., and Scedosporium sp. Reflecting a key need, important advances have been made in the antifungal armamentarium. Voriconazole has become a new standard of care as primary therapy for invasive aspergillosis based on superiority over amphotericin B. There is significant interest in combination therapy for invasive aspergillosis pairing voriconazole or an amphotericin B formulation with an echinocandin. There have also been advances in novel diagnostic methods that facilitate early detection of invasive fungal infections that include galactomannan and beta-glucan antigen detection and PCR using fungal specific primers. We review the epidemiology, diagnosis, and management of invasive mould infection in HSCT, with a focus on allogeneic recipients. We also discuss options for prevention and early treatment of invasive mould infections.

Genetic identification of the main opportunistic Mucorales by PCR-restriction fragment length polymorphism

Mucormycosis is a rare and opportunistic infection caused by fungi belonging to the order Mucorales. Recent reports have demonstrated an increasing incidence of mucormycosis, which is frequently lethal, especially in patients suffering from severe underlying conditions such as immunodeficiency. In addition, even though conventional mycology and histopathology assays allow for the identification of Mucorales, they often fail in offering a species-specific diagnosis. Due to the lack of other laboratory tests, a precise identification of these molds is thus notoriously difficult. In this study we aimed to develop a molecular biology tool to identify the main Mucorales involved in human pathology. A PCR strategy selectively amplifies genomic DNA from molds belonging to the genera Absidia, Mucor, Rhizopus, and Rhizomucor, excluding human DNA and DNA from other filamentous fungi and yeasts. A subsequent digestion step identified the Mucorales at genus and species level. This technique was validated using both fungal cultures and retrospective analyses of clinical samples. By enabling a rapid and precise identification of Mucorales strains in infected patients, this PCR-restriction fragment length polymorphism-based method should help clinicians to decide on the appropriate treatment, consequently decreasing the mortality of mucormycosis.

Rapid susceptibility testing of medically important zygomycetes by XTT assay

The XTT colorimetric assay quantifies fungal growth by measuring fungal metabolism and has been used successfully for susceptibility testing of Aspergillus species after 24 and 48 h of incubation. In the present study using 14 clinical isolates of Zygomycetes (Rhizopus oryzae [5 isolates], Cunninghamella spp. [3 isolates], Mucor spp. [3 isolates], and Absidia corymbifera [3 isolates]), significant metabolic activity was demonstrated before visual or spectrophotometric detection of fungal growth by performing the XTT assay as early as 6 h after inoculation. Testing of susceptibility to amphotericin B, posaconazole, and voriconazole was subsequently performed using the XTT method (100 microg/ml XTT, 25 microM menadione) at 6, 8, or 12 h after inoculation and the CLSI (formerly NCCLS) M38-A method with visual and spectrophotometric MIC determinations at 24 h after inoculation. Concentration-effect curves obtained with the use of the E(max) model (a sigmoid curve with variable slope) were comparable between the early XTT and spectrophotometric readings at 24 h. Complete inhibition of early metabolic activity with the azoles was delayed in comparison to that with amphotericin B. Using appropriate cutoff levels, agreement was demonstrated between the early XTT and 24-h spectrophotometric or visual readings. In particular, for MIC-0 (the lowest drug concentration showing absence of visual growth) of amphotericin B, overall agreement levels were 90 to 93% for the 6-h XTT assay and 100% for the 8- and 12-h time points. For MIC-0 of posaconazole, agreement levels were 86% for the 6-h XTT and 93 to 100% for the 8- and 12-h time points. The overall agreement levels for MIC-0 and MIC-2 (the lowest drug concentration showing prominent reduction of growth compared with the control well) of voriconazole (compared with 24-h spectrophotometric readings) were 93 to 98% for the 8- and 12-h XTT assays. These results support the use of the XTT method for rapid MIC determination for Zygomycetes.

Posaconazole Is Effective as Salvage Therapy in Zygomycosis: A Retrospective Summary of 91 Cases

To evaluate the activity of posaconazole for treatment of zygomycosis, a disease for which therapeutic options are limited, we conducted a retrospective study including 91 patients with zygomycosis (proven zygomycosis, 69 patients; probable zygomycosis, 22 patients). Patients had infection that was refractory to prior antifungal treatment (n=81) or were intolerant of such treatment (n=10) and participated in the compassionate-use posaconazole (800 mg/day) program. The rate of success (i.e., either complete or partial response) at 12 weeks after treatment initiation was 60%, and 21% of patients had stable disease. The overall high success and survival rates reported here provide encouraging data regarding posaconazole as an alternative therapy for zygomycosis.

Zygomycosis: the re-emerging fungal infection

Invasive fungal infections are major medical complications in immunocompromised patients. The recent rise in the incidence of cancer and the increased use of newer medical treatment modalities, including organ transplantations, have resulted in growing numbers of highly immunosuppressed individuals. Although aspergillosis and candidiasis are among the most common invasive mycoses in such patients, there is evidence that the incidence of infectious diseases caused by Zygomycetes has risen significantly over the past decade. Patients with diabetes, malignancies, solid organ or bone marrow transplants, or iron overload and those receiving immunosuppressive agents, deferoxamine therapy, or broad-spectrum antimicrobial drugs are at highest risk for zygomycosis. This review details the emergence and importance of zygomycosis in current clinical practice and its manifestations and management. The etiologic species, pathogenesis and risk factors for zygomycosis are reviewed and updated. The clinical spectrum of zygomycosis is now broader, and it can be difficult to distinguish between mucormycosis and enthomophthoramycosis, both of which can manifest as disease ranging from a superficial infection to an angioinvasive infection with high mortality. Finally, the three-part treatment strategy (antifungal drugs, surgery, control of underlying diseases) is reviewed. Lipid formulations of amphotericin B are the antifungal agents of choice for treatment of zygomycosis. A novel antifungal triazole, posaconazole, has been developed and may become approved for treatment of zygomycosis. The clinical experience with adjunctive treatments like colony-stimulating factors, interferon-gamma, and hyperbaric oxygen therapy is still limited.

Zygomycoses in patients with acute leukaemia

Zygomycoses are rare invasive mould infections which mainly occur in immunocompromised patients, especially during prolonged neutropenia. The high mortality rate is due to a high failure rate of both intravital diagnosis and treatment. Exact diagnosis requires microscopic examination and proof by culture. The treatment consists of amphotericin B and surgical debridement. We report four recent cases of zygomycosis among 89 patients with intensively treated acute leukaemia at our institution. Three cases were breakthrough infections since the patients were under voriconazole treatment prior to diagnosis of zygomycosis. Only one patient had premortal diagnosis (paranasal sinus infection) and showed clinical response with amphotericin B and surgical debridement. A review of the literature of these emerging fungal infections is given and is focused on patients with acute leukaemia. In addition, the importance of autopsy as a tool for quality control and epidemiological studies is pointed out.