Updated: Jul 1, 2008
Mucormycosis refers to several different diseases caused by infection with fungi in the order of Mucorales. Rhizopus species are the most common causative organisms. In descending order, the other genera with mucormycosis-causing species include Rhizomucor, Cunninghamella, Apophysomyces, Saksenaea, Absidia, Mucor, Syncephalastrum, Cokeromyces, and Mortierella. Most infections are life-threatening, and risk factors, such as diabetic ketoacidosis and neutropenia, are present in most cases. Severe infection of the facial sinuses, which may extend into the brain, is the most common presentation. Pulmonary, cutaneous, and Gi infections are also recognized. Successful treatment requires correction of the underlying risk factor or factors, antifungal therapy with amphotericin B, and aggressive surgery.
Mucoraceae are ubiquitous fungi that are commonly found in soil and in decaying matter. Rhizopus can be found in moldy bread. Given the ubiquitous nature of these fungi, most humans are exposed to these organisms on a daily or weekly basis. Nonetheless, they rarely cause disease because of the low virulence of the organisms and mainly affect individuals with immunocompromising conditions. Immunocompromised hosts with poorly controlled diabetes mellitus (especially with ketoacidosis), who are receiving glucocorticosteroids, who have neutropenia in the setting of hematological or solid malignancy, who have undergone transplantation, who have iron overload, and who have burns are at risk for disease.
The major route of infection is via inhalation of conida; other routes include ingestion and traumatic inoculation. For instance, nonsterile tape and contaminated wooden splints have caused wound infections. Such cases are associated with trauma, the presence of a pre-existing wound, or both. When spores are deposited in the nasal turbinates, rhinocerebral disease develops (see Rhinocerebral Mucormycosis); when spores are inhaled into the lungs, pulmonary disease develops. When the agents are introduced through abraded skin, cutaneous disease develops. Ingestion leads to GI disease, primarily among malnourished patients.
Mucoraceae are molds in the environment that become hyphal forms in tissues. Once the spores begin to grow, fungal hyphae invade blood vessels, producing tissue infarction, necrosis, and thrombosis. Neutrophils are the key host defense against these fungi; thus, individuals with neutropenia or neutrophil dysfunction (diabetes, steroid use) are at highest risk. Few cases of mucormycosis have been reported in patients with AIDS, suggesting that the host defense against this infection is not primarily mediated by cellular immunity.
Mucormycosis is extremely rare, and its incidence is difficult to calculate accurately. Rhinocerebral disease is the most common form, accounting for more than half of the cases. Other major syndromes include pulmonary, cutaneous, and disseminated diseases; rarer forms involve the GI tract and kidneys. Mucormycosis has been reported in immunocompetent individuals, mostly after traumatic inoculation of fungal spores, but this is extremely rare. A recent review of mucormycosis cases at one US cancer center found that 0.7% of patients were found to have mucormycosis at autopsy and that 20 patients per 100,000 admissions had the disease.1 The incidence of the mucormycosis appears to be increasing secondary to rising numbers of immunocompromised persons.
Mucormycosis was found in 1% of patients with acute leukemia in an Italian multicenter review.2
A related disease, entomophthoramycosis, is rare in the United States; it is most commonly found in Africa, Southeast Asia, Australia, and Central America. Entomophthoramycosis consists of 2 diseases: conidiobolomycosis (caused by Conidiobolus infection) and basidiobolomycosis (caused by Basidiobolus infection). The former presents as a painless, firm, subcutaneous mass that primarily involves the head and face, whereas the latter involves the trunk and/or extremities. In contrast with mucormycosis, entomophthoramycosis is associated with a lower mortality rate and usually affects immunocompetent hosts.
Mucormycosis carries a very high mortality rate (50-85%). Pulmonary and GI diseases carry an even higher mortality rate because these forms are typically diagnosed late in the disease course. Rhinocerebral disease causes significant morbidity in patients who survive because treatment usually requires extensive, and often disfiguring, facial surgery.
No racial factors that predispose people to mucormycosis exist.
Sex is not likely to affect the occurrence of mucormycosis because the underlying conditions are the major predisposing factors. Reviews of cases from single institutions show an equal sex distribution. However, a recent review of all published cases of pulmonary mucormycosis performed by Lee et al (1999) showed a male-to-female ratio of 3:1.3
Mucormycosis is found in patients of a wide age range.
Manifestations of mucormycosis depend on the location of involvement.
The physical signs of mucormycosis depend on the location of involvement.
Immunocompromising conditions are the main risk factor for mucormycosis. Patients with uncontrolled diabetes mellitus, especially with ketoacidosis, are at high risk. Patients with cancer, especially those who are neutropenic and have received broad-spectrum antibiotics, are also at risk. Patients receiving immunosuppressive agents, including oral or intravenous steroids, as well as tumor necrosis factor (TNF)alpha blockers, are at risk. Extreme malnutrition is also linked to mucormycosis, especially the GI form. Iron is a growth stimulant for Mucorales, and deferoxamine acts as a siderophore that delivers iron to the fungi. Deferoxamine therapy and all causes of iron overload are additional risk factors for mucormycosis. Trauma and the use of contaminated medical supplies over wounds are associated with cutaneous mucormycosis. In addition, patients with burns and those who use intravenous drugs are at a higher risk.
Some patients with mucormycosis have no identifiable risk factors.5
Anthrax
Aspergillosis
Cellulitis
Colonic Obstruction
Nocardiosis
Pulmonary Embolism
Rhinocerebral
Bacterial orbital cellulitis
Cavernous sinus thrombosis
Aspergillosis
Pseudallescheria boydii infection (Pseudallescheriasis)
Rapidly growing orbital tumor
Pulmonary
Aspergillosis
P boydii infection (pseudallescheriasis)
Pulmonary embolism
Skin
Ecthyma gangrenosa associated with pseudomonal infection
Anthrax
Gastrointestinal
Bowel obstruction
Ileocecal tuberculosis
The critical test procedure is obtaining a biopsy of involved tissue. Act promptly on the histological appearances of mucormycosis.
Pathognomonic changes of broad, irregular, nonseptate, right-angled, branching hyphae are demonstrated by H&E and by specialized fungal stains. Vascular invasion and necrosis are the characteristic consequences of the infective process. A neutrophil infiltrate is typical, and a granulomatous reaction may be observed.
Correction of the underlying abnormality and prompt institution of amphotericin B therapy and surgical resection are critical.
Debridement of necrotic tissue in combination with medical therapy is mandatory for survival.
Antifungal treatment consists of amphotericin B, lipid formulations of amphotericin, or posaconazole. Although most clinical experience has focused on amphotericin agents, data on the efficacy of posaconazole are promising. This may eventually become the drug of choice, but more evaluation is needed.
Amphotericin agents
Amphotericin B has proven efficacy in the treatment of mucormycosis. Amphotericin B is typically administered at 1-1.5 mg/kg/d. The total dose given over the course of therapy is usually 2.5-3 g. High doses of this drug are required, and nephrotoxicity may result. Lipid formulations of amphotericin B allow for very high doses to be administered while better protecting renal function. Whether lipid formulations of amphotericin B provide better therapeutic outcomes is not clear, and the high cost necessitates careful consideration of use.
Renal impairment and failed treatment with conventional amphotericin B are appropriate indications for the use of the lipid formulations. Lipid preparations of amphotericin B are used at 5 mg/kg/d. Some have doses of up to 15 mg/kg/d to treat mucormycosis.
Posaconazole, a new triazole, has recently been approved by the US Food and Drug Administration (FDA). Posaconazole is indicated for prophylaxis of invasive Aspergillus and Candida infections in patients at high risk because of severe immunosuppression. Posaconazole 400 mg twice daily is the typical dose used in the treatment of mucormycosis.
Studies have reported that posaconazole yielded a 50-70% success rate, while the comparator (typically amphotericin B or lipid-based amphotericin, in many cases used as salvage therapy) yielded a success rate of only 25%, suggesting that posaconazole may become the preferred drug for mucormycosis. However, further studies are needed.7,8
Posaconazole has also been studied in several case reports,6 including as salvage therapy after failure of amphotericin.9 Rickerts et al (2006) reported that liposomal amphotericin B plus posaconazole was successful in the treatment of disseminated mucormycosis in a patient who could not undergo surgery.10
Other medications
Other azoles (eg, fluconazole, voriconazole) and the echinocandins have not shown significant activity against these fungi. Of note, despite the use of voriconazole prophylaxis in high-risk patients (eg, transplant recipients), breakthrough zygomycosis has been reported.11,12
These agents are used to treat Mucorales infection. The mechanism of action may involve an alteration of RNA and DNA metabolism or an intracellular accumulation of peroxide that is toxic to the fungal cell.
DOC produced by a strain of Streptomyces nodosus. Can be fungistatic or fungicidal. Binds to sterols (eg, ergosterol) in fungal cell membrane, causing intracellular components to leak, with subsequent fungal cell death. Active against Cryptococcus neoformans, Histoplasma capsulatum, Coccidioides immitis, Candida species, and Aspergillus species.
1-1.5 mg/kg IV qd infused in 5% dextrose over 4-6 h
Administer as in adults
Antineoplastic agents may enhance the potential for renal toxicity, bronchospasm, and hypotension; corticosteroids, digitalis, and thiazides may potentiate hypokalemia; risk of renal toxicity is increased with cisplatin, pentamidine, and cyclosporine
Documented hypersensitivity; renal impairment
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Monitor renal function, serum electrolytes (eg, magnesium, potassium), liver function, CBC, and hemoglobin concentrations; hypoxemia, acute dyspnea, and interstitial infiltrates may occur in patients who are neutropenic and receiving leukocyte transfusions (separate time of amphotericin infusion from time of leukocyte transfusion); signs of infusion-related toxicity include fever, headache, hypotension, and phlebitis; normocytic and/or normochromic anemia may develop
Amphotericin B encapsulated in bilayer of liposomes. Antifungal agent of second choice when renal toxicity develops or conventional amphotericin B therapy is failing. Nephrotoxicity and infusion-related toxicity are reduced compared with conventional amphotericin B.
5 mg/kg/d IV
Administer as in adults
Antineoplastic agents may enhance the potential for renal toxicity, bronchospasm, and hypotension; corticosteroids, digitalis, and thiazides may potentiate hypokalemia; the risk of renal toxicity is increased with cyclosporine
Documented hypersensitivity
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Monitor renal function, serum electrolytes (eg, magnesium, potassium), liver function, CBC, and hemoglobin concentrations; hypoxemia, acute dyspnea, and interstitial infiltrates may occur in patients who are neutropenic and receiving leukocyte transfusions (separate time of amphotericin infusion from time of leukocyte transfusion)
Amphotericin B in phospholipid complexed form. Drug of third choice when conventional amphotericin B therapy is failing, but renal function is not impaired.
5 mg/kg/d IV
Administer as in adults
Antineoplastic agents may enhance the potential of amphotericin B for renal toxicity, bronchospasm, and hypotension; corticosteroids, digitalis, and thiazides may potentiate hypokalemia; the risk of renal toxicity is increased with cyclosporine
Documented hypersensitivity
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Infusion-related adverse effects are common and may require pretreatment with acetaminophen, diphenhydramine, and hydrocortisone; dose-limiting renal toxicity limits use; monitor renal function, serum electrolytes (eg, magnesium, potassium), liver function, CBC, and hemoglobin concentrations; hypoxemia, acute dyspnea, and interstitial infiltrates may occur in patients who are neutropenic and receiving leukocyte transfusions (separate time of amphotericin infusion from time of leukocyte transfusion)
Triazole antifungal agent. Blocks ergosterol synthesis by inhibiting the enzyme lanosterol 14-alpha-demethylase and sterol precursor accumulation. This action results in cell membrane disruption. Available as oral susp (200 mg/5 mL). Indicated for prophylaxis of invasive Aspergillus and Candida infections in patients at high risk because of severe immunosuppression. Has also been used for serious fungal infections (eg, invasive aspergillosis, Fusarium infection, Scedosporium apiospermum infection, candidemia, candidiasis).
Treatment of serious fungal infection: 800 mg/d (in 2 or 4 divided doses) with food or nutritional supplement
<13 years: Not established
>13 years: Administer as in adults
Metabolized via UDP glucuronidation; P-gp efflux substrate; CYP3A4 inhibitor
UDP-G inducers (eg, rifabutin, phenytoin) and drugs that increase gastric pH (eg, cimetidine) decrease serum levels (avoid concomitant use unless benefit outweighs risk)
Inhibits CYP3A4 and may elevate serum levels of cyclosporine, tacrolimus, sirolimus, rifabutin, midazolam, phenytoin, calcium channel blockers (eg, nifedipine, bepridil), HMG-CoA reductase inhibitors (eg, lovastatin, pravastatin), ergot alkaloids, terfenadine, astemizole, cisapride, pimozide, halofantrine, quinidine, or vinca alkaloids (eg, vincristine, vinblastine)
Documented hypersensitivity; coadministration with ergot alkaloids; coadministration with CYP3A4 substrates likely to result in serious toxicities (eg, terfenadine, astemizole, cisapride, pimozide, halofantrine, quinidine)
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Common adverse effects include nausea, vomiting, diarrhea, rash, hypokalemia, thrombocytopenia, and elevated liver enzyme levels; closely monitor patients with severe diarrhea or vomiting for breakthrough fungal infections; rare adverse events include arrhythmias caused by QTc prolongation, bilirubinemia, or liver function impairment; caution with preexisting cardiac risk factors (eg, history of arrhythmia, hypokalemia, hypomagnesemia); food improves absorption and provides optimal serum concentration; shake well before use; administer with measuring spoon provided in package; avoid if breastfeeding
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Sedlacek M, Cotter JG, Suriawinata AA, et al. Mucormycosis peritonitis: more than 2 years of disease-free follow-up after posaconazole salvage therapy after failure of liposomal amphotericin B. Am J Kidney Dis. Feb 2008;51(2):302-6. [Medline].
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Rhizopus species, mucormycosis, zygomycosis, phycomycosis, Mucorales, Rhizopus mucormycosis , Rhizomucor mucormycosis , Cunninghamella mucormycosis , Apophysomyces mucormycosis , Saksenaea mucormycosis , Absidia mucormycosis , Mucor mucormycosis , Syncephalastrum mucormycosis , Cokeromyces mucormycosis , Mortierella mucormycosis, conidiobolomycosis, entomophthoramycosis, basidiobolomycosis, pulmonary mucormycosis, rhinocerebral mucormycosis, cutaneous mucormycosis, gastrointestinal mucormycosis, disseminated mucormycosis
Nancy F Crum-Cianflone, MD, MPH, Consulting Staff, Department of Internal Medicine, Division of Infectious Diseases, Naval Medical Center at San Diego; HIV Research Physician, Infectious Disease Clinical Research Program, Uniformed Services University of the Health Sciences
Nancy F Crum-Cianflone, MD, MPH is a member of the following medical societies: American College of Physicians and Infectious Diseases Society of America
Disclosure: Nothing to disclose.
Maria D Mileno, MD, Assistant Professor, Department of Internal Medicine, Division of Infectious Diseases, Brown University
Maria D Mileno, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians, American Society of Tropical Medicine and Hygiene, Infectious Diseases Society of America, International Society of Travel Medicine, and Sigma Xi
Disclosure: Nothing to disclose.
Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.
Ronald A Greenfield, MD, Professor, Department of Internal Medicine, Section of Infectious Diseases, University of Oklahoma College of Medicine
Ronald A Greenfield, MD is a member of the following medical societies: American College of Physicians, American Federation for Medical Research, American Society for Microbiology, Central Society for Clinical Research, Infectious Diseases Society of America, Medical Mycology Society of the Americas, Phi Beta Kappa, Southern Society for Clinical Investigation, and Southwestern Association of Clinical Microbiology
Disclosure: Pfizer Honoraria Speaking and teaching; Gilead Honoraria Speaking and teaching; Ortho McNeil Honoraria Speaking and teaching; Wyeth Honoraria Speaking and teaching; Abbott Honoraria Speaking and teaching; Astellas Honoraria Speaking and teaching; Cubicin Speaking and teaching
Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital
Eleftherios Mylonakis, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Society for Microbiology, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.
Burke A Cunha, MD, Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital
Burke A Cunha, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.
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