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

Breakthrough disseminated zygomycosis induced massive gastrointestinal bleeding in a patient with acute myeloid leukemia receiving micafungin

A 69-year-old man, who had been receiving prednisolone for 11 months for treatment of interstitial pneumonia, was diagnosed with acute myeloid leukemia. During induction therapy, he developed severe pneumonia. Although meropenem and micafungin were started, he died of circulatory failure owing to massive gastrointestinal bleeding. Autopsy specimens obtained from the stomach revealed fungal hyphae, which had invaded diffusely into submucosal vessels and caused the massive gastric bleeding. The same hyphae were also observed in both lungs. A diagnosis of disseminated zygomycosis was confirmed by its characteristic histopathological findings. Because zygomycetes are spontaneously resistant to the newer antifungal agents, such as voriconazole or micafungin, it seems likely that the prevalence of zygomycosis as a breakthrough infection may increase in the future. Zygomycosis is a rare, but life-threatening, deep fungal infection that appears in immunologically or metabolically compromised hosts. Its manifestations are clinically similar to those of invasive aspergillosis. In addition to the well-established epidemiology of zygomycosis, this case suggests the following new characteristics. (1) Although the gastrointestinal manifestation of zygomycosis is relatively rare, it is observed more frequently than invasive aspergillosis. (2) Gastrointestinal zygomycosis occasionally leads to the development of necrotic ulcers and may induce hemorrhagic shock.(3) We should be cautious of an occurrence of breakthrough zygomycosis when we use echinocandins for patients with known risk factors, especially steroid use and neutropenia. (4) For patients who are receiving broad-spectrum antibiotics and echinocandins, who are negative for culture studies and aspergillus antigen, and who present with unresolved fever, it is important to make a prompt clinical diagnosis of zygomycosis.

Update on the epidemiology and diagnosis of invasive fungal infection

In recent years, the most important advances in the treatment of transplant recipients, patients with haematological neoplasm and critically ill patients have been accompanied by an increase in the incidence of common fungal diseases and the emergence of some less common ones. Although new techniques (e.g. galactomannan detection) and new antifungals have appeared, these opportunistic infections remain difficult to diagnose and have a high mortality. New diagnostic techniques could improve this outlook, although they are far from becoming available in daily practice.

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.

Activity of posaconazole and other antifungal agents against Mucorales strains identified by sequencing of internal transcribed spacers

The antifungal susceptibility profiles of 77 clinical strains of Mucorales species, identified by internal transcribed spacer sequencing, were analyzed. MICs obtained at 24 and 48 h were compared. Amphotericin B was the most active agent against all isolates, except for Cunninghamella and Apophysomyces isolates. Posaconazole also showed good activity for all species but Cunninghamella bertholletiae. Voriconazole had no activity against any of the fungi tested. Terbinafine showed good activity, except for Rhizopus oryzae, Mucor circinelloides, and Rhizomucor variabilis isolates.

Mucor circinelloides as a cause of invasive maxillofacial zygomycosis: an emerging dimorphic pathogen with reduced susceptibility to posaconazole

A case of maxillofacial zygomycosis caused by Mucor circinelloides, identified by phenotypic and molecular methods and treated successfully with liposomal amphotericin B (AmBisome) and surgical debridement, is described. The isolate was resistant to posaconazole. This report underscores the importance of prior susceptibility testing of zygomycetes to guide therapy with the most effective antifungal agent for an improved prognosis.

Thyroid involvement in disseminated zygomycosis by Cunninghamella bertholletiae: 2 cases and literature review

Thyroid involvement is very rare in disseminated zygomycosis. We describe two cases of thyroiditis due to Cunninghamella bertholletiae diagnosed though a necropsy study and the only five previous cases of thyroid zygomycosis reported in the literature are revised.

Pharmacokinetics of oral posaconazole in neutropenic patients receiving chemotherapy for acute myelogenous leukemia or myelodysplastic syndrome

STUDY OBJECTIVE

To analyze the pharmacokinetics of posaconazole administered as prophylaxis for invasive fungal infection (IFI) in neutropenic patients receiving chemotherapy for acute myelogenous leukemia (AML) or myelodysplastic syndrome (MDS).

DESIGN

Pharmacokinetic subanalysis of a phase III, prospective, randomized, multicenter, evaluator-blinded trial comparing posaconazole with standard azoles (fluconazole and itraconazole).

PATIENTS

One hundred ninety-four patients with AML or MDS who received posaconazole oral suspension 200 mg 3 times/day with meals or a nutritional supplement for a minimum of 7 days to achieve steady state and for a maximum of 12 weeks.

INTERVENTION

For the first 20 patients, blood samples were collected before the first dose on day 8 and at 2, 4, 6, and 24 hours after that first dose; for all other patients, blood samples were collected at 1 and 3 hours after the first dose on day 8 and during the first episode of evaluation for a possible IFI.

MEASUREMENTS AND MAIN RESULTS

The effects of the following covariates on average (Cav) and maximum (Cmax) posaconazole plasma concentrations at steady state were explored: age, sex, and race-ethnicity; proven or probable IFI; baseline body weight and body surface area; and baseline (on or before day 7) increases in liver enzyme levels, mucositis, neutropenia, diarrhea, vomiting, or use of an H2-receptor antagonist or proton pump inhibitor. Diarrhea, proton pump inhibitor use, gamma-glutamyl transferase level of 2 or more times the upper limit of normal, and race-ethnicity reduced Cav. Although statistically significant, these results were not considered clinically significant and did not necessitate posaconazole dosage adjustments. Mean Cav and Cmax values did not appear different in the six patients with IFIs (three with proven IFIs, three with probable IFIs) compared with the entire sample of 194 patients; however, a definitive conclusion cannot be made due to the small sample size of patients with IFI. No factor found to affect posaconazole concentrations predominated in patients with IFIs.

CONCLUSION

Oral posaconazole 200 mg 3 times/day provided plasma concentrations adequate for preventing IFIs. No dosage adjustments are recommended based on any covariate tested.

Pleuropulmonary zygomycosis in a diabetic child

A 12 yr old girl with type 1 diabetes presented in ketoacidosis and consolidation of left lower lobe along with left pleural effusion. A diagnosis of mucormycosis was made on smear examination of an exudative pleural aspirate. Left lower lobe lobectomy was performed along with drainage of pleural collection with tube thoracostomy. Worsening respiratory distress postoperatively due to increase in empyema fluid necessitated a second surgery. Pleuropulmonary involvement as seen in this patient is an extremely rare occurrence possibly related to the propensity of mucor to invade blood vessels rather than extend outwardly into pleural cavity.

Fungal Infections

Older adults are at increased risk of developing opportunistic fungal infections because organ transplantation, intensive cancer chemotherapy regimens, and anti-tumor necrosis factor agents are now used more commonly, and because admission to an intensive care unit, which carries many risk factors for fungal infection, has become commonplace in this group.

Candida species are the most common cause of opportunistic fungal infections, and bloodstream infections are usually treated with fluconazole or an echinocandin antifungal agent.

Invasive mold infections are mostly caused by Aspergillus species; in older adults, they cause primarily pulmonary and sinus infections, and they are associated with a high mortality rate.

The endemic fungi, Histoplasma capsulatum, Coccidioides species, and Blastomyces dermatitidis, cause infection when the mold form is dispersed and inhaled from the environment in those specific areas of the country in which these organisms flourish.

Amphotericin B is used for initial treatment of severe histoplasmosis, coccidioi­domycosis, and blastomycosis; itraconazole is the therapy of choice for most mild to moderate infections due to these endemic mycoses.

Economic burden of mucormycosis in the United States: can a vaccine be cost-effective?

Mucormycosis is a life-threatening infection which causes unacceptably high morbidity and mortality despite treatment. Therefore, a vaccine to prevent mucormycosis is desirable. A major barrier to developing an anti-mucormycosis vaccine is the perception that such a vaccine would not be cost-effective to deploy because the disease is rare. We used data from a recent retrospective study to calculate the annual cost to the US healthcare system caused by mucormycosis infections. We created a model to estimate the cost-efficacy of a niche, anti-mucormycosis vaccine deployed in a targeted manner to high-risk patients. We found that each case of mucormycosis results in an average direct cost to the US healthcare system of $97,743, for an overall cost of mucormycosis of $50 million per year. In the base case scenario, targeted deployment of an anti-mucormycosis vaccine would result in a net cost per quality adjusted life year saved (QUALY) of $17,249. Variations in the price of the vaccine, its market penetration, or the cost of infection could dramatically decrease the net cost, and could even result in net savings per QUALY. In conclusion, mucormycosis causes considerable cost to the US health care system. Targeted deployment of a niche vaccine could decrease infection rates and mortality from mucormycosis in a cost-effective manner.

Detection of a molecular biomarker for zygomycetes by quantitative PCR assays of plasma, bronchoalveolar lavage, and lung tissue in a rabbit model of experimental pulmonary zygomycosis

We developed two real-time quantitative PCR (qPCR) assays, targeting the 28S rRNA gene, for the diagnosis of zygomycosis caused by the most common, clinically significant Zygomycetes. The amplicons of the first qPCR assay (qPCR-1) from Rhizopus, Mucor, and Rhizomucor species were distinguished through melt curve analysis. The second qPCR assay (qPCR-2) detected Cunninghamella species using a different primer/probe set. For both assays, the analytic sensitivity for the detection of hyphal elements from germinating sporangiospores in bronchoalveolar lavage (BAL) fluid and lung tissue homogenates from rabbits was 1 to 10 sporangiospores/ml. Four unique and clinically applicable models of invasive pulmonary zygomycosis served as surrogates of human infections, facilitating the validation of these assays for potential diagnostic utility. For qPCR-1, 5 of 98 infarcted lung specimens were positive by qPCR and negative by quantitative culture (qCx). None were qCx positive only. Among 23 BAL fluid samples, all were positive by qPCR, while 22 were positive by qCx. qPCR-1 detected Rhizopus and Mucor DNA in 20 (39%) of 51 serial plasma samples as early as day 1 postinoculation. Similar properties were observed for qPCR-2, which showed greater sensitivity than qCx for BAL fluid (100% versus 67%; P = 0.04; n = 15). The assay detected Cunninghamella DNA in 18 (58%) of 31 serial plasma samples as early as day 1 postinoculation. These qPCR assays are sensitive and specific for the detection of Rhizopus, Mucor, Rhizomucor, and Cunninghamella species and can be used for the study and detection of infections caused by these life-threatening pathogens.

Eleven cases of mucormycosis with atypical clinical manifestations in diabetic patients

OBJECTIVE

We retrospectively investigated 11 cases of mucormycosis with atypical clinical features accompanied by diabetes mellitus and discussed clinical features, results of laboratory investigations and radiological examinations and treatment outcomes of each case.

METHODS

Eleven cases of mucormycosis presenting to our clinic between January 2002 and October 2006 were retrospectively investigated.

RESULTS

We will present a total of 11 cases of mucormycosis, including 2 cases of mucormycosis with orbital apex syndrome as an initial sign, 2 cases of mucormycosis involving the carotid artery and cavernous sinus with the resultant fatal stroke, 1 case of disseminated mucormycosis with atypical clinical manifestations. Mucormycosis was accompanied by type II diabetes mellitus in five cases, chronic renal failure and type II diabetes mellitus in four cases and type II diabetes mellitus and chronic myelocytic leukemia in two cases. None of them had diabetic ketoacidosis. Only one patient recovered but with sequels: blindness, complete ophthalmoplegia of the right eye. Ten patients died of mucormycosis.

CONCLUSION

In fact, mucormycosis is a fungal infection which may involve all organs and systems. Mucormycosis must be considered in patients presenting with orbital or preorbital sellulitis, even in the absence of ketoacidosis as in our cases.

Recommendations for the treatment of established fungal infections

Evidence-based guidelines for the treatment of established fungal infections in the adult haematology/oncology setting were developed by a national consensus working group representing clinicians, pharmacists and microbiologists. These updated guidelines replace the previous guidelines published in the Internal Medicine Journal by Slavin et al. in 2004. The guidelines are pathogen-specific and cover the treatment of the most common fungal infections including candidiasis, aspergillosis, cryptococcosis, zygomycosis, fusariosis, scedosporiosis, and dermatophytosis. Recommendations are provided for management of refractory disease or salvage therapies, and special sites of infections such as the cerebral nervous system and the eye. Because of the widespread use newer broad-spectrum triazoles in prophylaxis and empiric therapy, these guidelines should be implemented in concert with the updated prophylaxis and empiric therapy guidelines published by this group.

Posaconazole mono- or combination therapy for treatment of murine zygomycosis

We compared the efficacy of combination posaconazole-liposomal amphotericin B (LAmB) therapy to monotherapy with either drug in diabetic ketoacidotic or neutropenic mice with disseminated zygomycosis caused by Rhizopus oryzae. Combination therapy was no better than LAmB alone, and posaconazole monotherapy did not improve survival or reduce fungal burden versus placebo.

Bacterial endosymbiosis is widely present among zygomycetes but does not contribute to the pathogenesis of mucormycosis

Environmental isolates of the fungus Rhizopus have been shown to harbor a bacterial endosymbiont (Burkholderia) that produces rhixozin, a plant mycotoxin. We sought to define the role of rhizoxin production by endosymbionts in the pathogenesis of mucormycosis. Endosymbiotic bacteria were identified by polymerase chain reaction in 15 (54%) of 28 clinical isolates of Zygomycetes, with 33% of the bacterial strains showing 87% identity to Burkholderia 16S rDNA. The presence of rhizoxin in myclial extracts from fungi harboring bacteria was confirmed by high-performance liquid chromatography analysis. However, fungal strains with or without endosymbionts did not differ in their ability to cause endothelial cell injury in vitro, nor did antibiotic-mediated eradication of endosymbionts and rhizoxin production decrease the virulence of fungal strains in mice or flies. In summary, although bacterial endosymbiosis is widely detected in clinical isolates of Zygomycetes, including Rhizopus oryzae strains, we found no evidence that bacterial endosymbionts and rhizoxin contribute to the pathogenesis of mucormycosis in the models studied.

Posaconazole combined with amphotericin B, an effective therapy for a murine disseminated infection caused by Rhizopus oryzae

In a murine model of disseminated zygomycosis, low doses of amphotericin B (0.3 mg/kg body weight/day) combined with posaconazole (40 mg/kg/day) prolonged survival and reduced tissue burden with respect to that of controls and that of both drugs administered alone. Results were similar to those obtained with amphotericin B given alone at 0.8 mg/kg/day.

Combination polyene-caspofungin treatment of rhino-orbital-cerebral mucormycosis

BACKGROUND

It has been axiomatic that echinocandins (e.g., caspofungin) are ineffective against mucormycosis. However, on the basis of preclinical data, we recently began treating rhino-orbital-cerebral mucormycosis (ROCM) with combination polyene-caspofungin therapy.

METHODS

To determine the impact of polyene-caspofungin therapy, ROCM cases identified by an International Classification of Diseases, Ninth Revision search were retrospectively reviewed to gather data on demographic characteristics, clinical history, and outcomes. The predefined primary end point was success (i.e., the patients was alive and not in hospice care) at 30 days after hospital discharge.

RESULTS

Forty-one patients with biopsy-proven ROCM were identified over 12 years; 23 (56%) of these patients were Hispanic, and 34 (83%) were diabetic. Patients treated with polyene-caspofungin therapy (6 evaluable patients) had superior success (100% vs. 45%; Pp.02) and Kaplan-Meier survival time (Pp.02), compared with patients treated with polyene monotherapy. Patients treated with amphotericin B lipid complex had inferior success (37% vs. 72%; Pp.03) and a higher clinical failure rate (45% vs. 21%; Pp.04), compared with patients who received other polyenes. However, patients treated with amphotericin B lipid complex plus caspofungin had superior success (100% vs. 20%; Pp.009) and survival time (Pp.01), compared with patients who received amphotericin B lipid complex alone. The benefit of combination therapy, compared with monotherapy, was most pronounced in patients with cerebral involvement (success rate, 100% vs. 25%; Pp.01). In multivariate analysis, only receipt of combination therapy was significantly associated with improved outcomes (odds ratio, 10.9; 95% confidence interval, 1.3- ;Pp.02).

CONCLUSIONS

Combination polyene-caspofungin therapy represents a promising potential alternative to polyene monotherapy for patients with ROCM. Randomized, prospective investigation of these findings is warranted.

Molecular diagnosis of Saksenaea vasiformis cutaneous infection after scorpion sting in an immunocompetent adolescent

We report the first case of cutaneous mucormycosis after a scorpion sting in Tunisia. Histopathology showed broad aseptate hyphae suggestive of a Zygomycete. Saksenaea vasiformis was identified by PCR amplification and sequencing of the fungal DNA on a cutaneous biopsy. Successful treatment was obtained by surgery and liposomal amphotericin B.

Drosophila melanogaster as a model host to dissect the immunopathogenesis of zygomycosis

Zygomycosis is an emerging frequently fatal opportunistic mycosis whose immunopathogenesis is poorly understood. We developed a zygomycosis model by injecting Drosophila melanogaster flies with a standardized amount of fungal spores from clinical Zygomycetes isolates to study virulence and host defense mechanisms. We found that, as opposed to most other fungi, which are nonpathogenic in D. melanogaster (e.g., Aspergillus fumigatus), Zygomycetes rapidly infect and kill wild-type flies. Toll-deficient flies exhibited increased susceptibility to Zygomycetes, whereas constitutive overexpression of the antifungal peptide Drosomycin in transgenic flies partially restored resistance to zygomycosis. D. melanogaster Schneider 2 phagocytic cells displayed decreased phagocytosis and caused less hyphal damage to Zygomycetes compared with that to A. fumigatus. Furthermore, phagocytosis-defective eater mutant flies displayed increased susceptibility to Zygomycetes infection. Classic enhancers of Zygomycetes virulence in humans, such as corticosteroids, increased iron supply, and iron availability through treatment with deferoxamine dramatically increased Zygomycetes pathogenicity in our model. In contrast, iron starvation induced by treatment with the iron chelator deferasirox significantly protected flies infected with Zygomycetes. Whole-genome expression profiling in wild-type flies after infection with Zygomycetes vs. A. fumigatus identified genes selectively down-regulated by Zygomycetes, which act in pathogen recognition, immune defense, stress response, detoxification, steroid metabolism, or tissue repair or have unknown functions. Our results provide insights into the factors that mediate host-pathogen interactions in zygomycosis and establish D. melanogaster as a promising model to study this important mycosis.