Mucormycosis, previously called zygomycosis, refers to several different diseases caused by infection with fungi in the order Mucorales. Rhizopus species are the most common causative organisms. In descending order, the other genera with mucormycosis-causing species include Mucor, Cunninghamella, Apophysomyces, Lichtheimia (formerly Absidia), Saksenaea, Rhizomucor, and other species.[1, 2]
Most mucormycosis 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 gastrointestinal (GI) infections are also recognized.
Successful mucormycosis treatment requires correction of the underlying risk factor(s), antifungal therapy (traditionally with a polyene), and aggressive surgery.
The following is a postmortem image of a patient who had diabetic ketoacidosis and left rhinocerebral mucormycosis.
View Image | Postmortem photograph of a woman with diabetes and left rhinocerebral mucormycosis complicating ketoacidosis. Rhizopus oryzae was the causative organi.... |
See also Pediatric Mucormycosis and Rhinocerebral Mucormycosis.
Immunocompromising conditions are the main risk factor for mucormycosis. Patients with uncontrolled diabetes mellitus, especially those with ketoacidosis, are at high risk. Other high risk groups include patients with cancer, especially those who are neutropenic and receiving broad-spectrum antibiotics, and individuals receiving immunosuppressive agents, including oral or intravenous steroids and tumor necrosis factor (TNF)-alpha blockers. In addition, patients with hematologic cancer who have opportunistic herpetic infections (eg, cytomegalovirus) and graft versus host disease (GVHD) are at an increased risk.
Extreme malnutrition is also linked to mucormycosis, especially the gastrointestinal (GI) form. Iron is a growth stimulant for Mucorales, and deferoxamine acts as a siderophore that delivers iron to the fungi. Older iron chelators such as deferoxamine 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.[3, 4]
Mucorales 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; instead, they 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 hematologic 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 conidia; other routes include ingestion and traumatic inoculation (see the images below). Ingestion leads to GI disease and occurs primarily among malnourished patients but can also occur after ingesting nonnutritional substances (pica). Regarding cutaneous disease, nonsterile tape and contaminated wooden splints have caused wound infections.[5, 6] Such cases are associated with trauma/surgery, the presence of a preexisting wound or line, or both. In addition, mucormycosis should be considered in the differential diagnoses of a necrotic-appearing wound or one with a poor response to antibiotic treatment following natural disasters (eg, hurricanes, tsunamis, tornadoes).[7, 8, 9]
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 ingested, GI disease ensues; and when the agents are introduced through interrupted skin, cutaneous disease develops.
View Image | The right eye of an immunocompetent man who sustained a high-pressure water jet injury, resulting in rhinocerebral mucormycosis. Traumatic inoculation.... |
View Image | The right eye of an immunocompetent man who sustained a high-pressure water jet injury, resulting in rhinocerebral mucormycosis. Traumatic inoculation.... |
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 (eg, diabetes, steroid use) are at highest risk.[10] Few cases of mucormycosis have been reported in patients with acquired immunodeficiency syndrome (AIDS), suggesting that the host defense against this infection is not primarily mediated by cellular immunity.
Based on anatomic localization, mucormycosis can be classified as 1 of 6 forms: (1) rhinocerebral, (2) pulmonary, (3) cutaneous, (4) gastrointestinal, (5) disseminated, and (6) uncommon presentations.[11] Rhinocerebral disease is the most common form in the United States, accounting for more than half of the cases. Most cases occur among severely immunocompromised persons. Mucormycosis has been reported in immunocompetent individuals, mostly after traumatic inoculation of fungal spores, but this is rare.
Mucormycosis is extremely rare, and its incidence is difficult to calculate accurately. Further, since mucormycosis is not a reportable disease, the true incidence is unknown. An estimated 500 cases occur in the United States annually.[1]
A review of mucormycosis cases at one US cancer center found that 0.7% of patients had mucormycosis at autopsy and that 20 patients per 100,000 admissions had the disease.[12] The 1-year cumulative incidence of mucormycosis has been estimated at approximately 4 cases per 1000 stem cell transplantations and 0.6 case per 1000 solid organ transplantations, accounting for 7% and 2% of all fungal infections in these populations, respectively.[13]
The incidence of mucormycosis appears to be increasing secondary to rising numbers of immunocompromised persons. There are also increasing reports of breakthrough mucormycosis in the setting of antifungal prophylaxis or treatment (eg, voriconazole, echinocandins) that is effective against most fungi, namely Aspergillus, but not mucormycosis. With improvements in early diagnosis via modalities such as matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF), polymerase chain reaction (PCR), and 18s rRNA sequencing, it has been suggested that mucormycosis is the cause of more than 10% of invasive fungal infections.[14, 15]
Additionally, several cases of cutaneous mucormycosis due to the Mucormycete Apophysomyces trapeziformis were described among wound-injured victims from a tornado.[8, 16, 17]
Descriptions of mucormycosis appear to be increasing, likely owing to rising numbers of at-risk persons.[18] Mucormycosis was found in 1% of patients with acute leukemia in an Italian multicenter review.[19]
A related disease, entomophthoramycosis, is rare in the United States but is most commonly found in Africa, Southeast Asia, Australia, and Central America. Entomophthoramycosis consists of two diseases: conidiobolomycosis (caused by Conidiobolus infection) and basidiobolomycosis (caused by Basidiobolus infection). Conidiobolomycosis presents as a painless, firm, subcutaneous mass that primarily involves the head and face, whereas basidiobolomycosis involves the trunk and/or extremities. In contrast with mucormycosis, entomophthoramycosis is associated with a lower mortality rate and usually affects immunocompetent hosts.
No clear racial or age factors that predispose people to mucormycosis exist. Reviews of cases from single institutions show an equal sex distribution, however a review of all published cases of pulmonary mucormycosis performed by Lee et al showed a male-to-female ratio of 3:1.[20]
Rhinocerebral disease causes significant morbidity in patients who survive, because treatment usually requires extensive, and often disfiguring, facial surgery.
Surviving mucormycosis requires rapid diagnosis and aggressive coordinated medical and surgical therapy.
Mucormycosis carries a mortality rate of 50-85%. The mortality rate associated with rhinocerebral disease is 50-70%. Pulmonary and gastrointestinal (GI) diseases carry an even higher mortality rate, because these forms are typically diagnosed late in the disease course. Disseminated disease carries a mortality rate that approaches 100%. Cutaneous disease carries the lowest mortality rate (15%). The advent of novel antifungals such as isavuconazole may offer improvement in these mortality rates; however, further studies are needed.
Based on anatomic localization, mucormycosis can be classified as 1 of 6 forms: (1) rhinocerebral, (2) pulmonary, (3) cutaneous, (4) gastrointestinal, (5) disseminated, and (6) uncommon presentations.[11] Manifestations of mucormycosis depend on the location of involvement.
Rhinocerebral disease may manifest as unilateral, retro-orbital headache, facial pain, numbness, fever, hyposmia, and nasal congestion, which progresses to black discharge. Initially, mucormycosis may mimic bacterial sinusitis.[21, 22]
Late symptoms that indicate invasion of the orbital nerves and vessels include diplopia and visual loss (see the following image). These late symptoms indicate a poor prognosis and are usually followed by a reduced level of consciousness. Most patients with rhinocerebral disease have diabetes (especially with ketoacidosis) or have malignancies with associated neutropenia and may be receiving broad-spectrum antibiotics.
View Image | An immunocompetent man who sustained a high-pressure water jet injury, resulting in rhinocerebral mucormycosis. Traumatic inoculation of Apophysomyces.... |
Orbital swelling and facial cellulitis are progressive. Necrotic eschars with black purulent discharge can be noted in the nasal cavity, on the hard palate, or on the face. Although these lesions suggest mucormycosis, their absence does not exclude the possibility of this disease.
Proptosis, ptosis, chemosis, and ophthalmoplegias indicate retro-orbital extension. Cranial nerves V and VII are the most commonly affected. Loss of vision can occur with retinal artery thrombosis.
A reduced level of consciousness state denotes brain involvement.
Pulmonary mucormycosis manifests nonspecifically as fever, dyspnea, and cough. Hemoptysis may occur in the presence of necrosis. Most patients with pulmonary disease have hematologic malignancies and a history of neutropenia.[23] Pulmonary disease frequently occurs with concurrent sinus involvement.
The signs of pulmonary disease are nonspecific. Fevers are often noted. The lung examination may reveal decreased breath sounds and rales. Occasionally, chest wall cellulitis can occur adjacent to the underlying parenchymal disease, given the ability of this infection to cross tissue planes.
Cutaneous disease manifests as cellulitis, which progresses to dermal necrosis and black eschar formation. The progressive black necrotic lesion of cutaneous mucormycosis reflects the vascular invasion characteristic of all forms of the disease.
Patients with skin disease may have had previous trauma or have been exposed to contaminated medical equipment, such as bandages.[5, 6] Rare cases have occurred at catheter sites or insulin or illicit drug injection sites.
Gastrointestinal (GI) mucormycosis usually affects severely malnourished individuals. Some case reports have described GI mucormycosis in transplant patients (eg, renal transplant). This infection may occur throughout the GI tract but most commonly affects the stomach, ileum, and colon. Again, the presentation is nonspecific, with abdominal pain, distention, nausea, and vomiting. Hematochezia[24] or obstruction[25] may occur. Some patients have tenderness to palpation or a mass. Rupture may lead to signs of peritonitis.
Other disseminated forms of mucormycosis may involve the kidneys, bones, heart, and other locations, with symptoms attributed to these organ systems. Peritonitis in the setting of continuous ambulatory peritoneal dialysis has also been described.[26]
Central nervous system (CNS) disease manifests as headache, decreasing level of consciousness, and focal neurologic symptoms/signs including cranial nerve deficits. Patients with CNS involvement may have a history of open head trauma, intravenous drug use, or malignancy.
Timely diagnosis is paramount in cases of mucormycosis.[27] Persons with suspected rhinocerebral disease should undergo emergent computed tomography (CT) imaging of the paranasal sinuses and an endoscopic examination of their nasal passages with biopsies of any suggestive lesions. The diagnosis of mucormycosis is established by obtaining a biopsy specimen of the involved tissue, and frozen tissue samples should be immediately evaluated for signs of infection. Tissue should also be sent for routine pathology examination and cultures. Swabs of tissue or discharge are unreliable.
For pulmonary disease, a bronchoalveolar lavage (BAL), biopsy, or both may assist in the diagnosis.
For cutaneous disease, a skin biopsy for pathology and culture should be obtained.
A complete blood cell (CBC) count should be obtained to assess for neutropenia. A chemistry panel that includes blood glucose, bicarbonate, and electrolytes is useful to monitor homeostasis and direct correction of acidosis. An arterial blood gas (ABG) study can help determine the degree of acidosis and guide corrective therapy.
Iron studies may be indicated to assess the presence of iron overload as shown by high ferritin levels and a low total iron-binding capacity.
In cases of central nervous system (CNS) involvement, cerebrospinal fluid (CSF) findings may include elevated protein levels and a modest mononuclear pleocytosis. CSF cultures are typically sterile. A CT scan should precede a lumbar puncture to assess for evidence of elevated intracranial pressure, which could lead to herniation.
Blood cultures can be obtained; however, they are usually negative despite the angioinvasive nature of the organism. Blood cultures may be useful to detect bacteremia in addition to Mucorales infection. One study of pulmonary mucormycosis identified concurrent bacteremia as an independent predictor of 28-day mortality.[23] There are no specific biomarkers to identify mucormycosis. Bronchoalveolar lavage (BAL) of fluid culture has a low yield, with a sensitivity of 20%-50%. Antigen tests (beta-D-glucan or galactomannan) are not useful for detecting this infection.[14]
The use of quantitative polymerase chain reaction (qPCR) for detection of circulating DNA from common Mucorales species (Lichtheimia species, Rhizomucor species, and Mucor/Rhizopus species), while not yet commercially available, has been described and appears promising for the early diagnosis of mucormycosis in high-risk patients.[28, 29] In a retrospective analysis of 44 cases, qPCR identification was fully concordant with that of culture. Assay positivity was observed at an average of 9 days, at least 2 days prior to positive imaging findings. Development of PCR negativity after treatment was associated with higher survival rates (48% vs 4%), suggesting that this modality could eventually be used for treatment monitoring.[30]
Imaging should be used to investigate areas of suspected mucormycosis. Because subclinical disease may be present, a thorough history and physical examination are recommended in addition to imaging (CT) of the brain, sinuses, chest, and abdomen.[31]
Plain films may show sinus involvement with mucosal thickening, air-fluid levels, and/or bony erosions.[22]
Head and facial CT imaging should be used as the initial investigation in rhinocerebral infections. CT scans may show sinusitis of the ethmoid and sphenoid sinuses, as well as orbital and intracranial extension. As the disease progresses, bony erosion may occur and the infection may spread into the brain or orbits. In addition, because mucormycosis organisms have a predilection for vascular involvement, thromboses of the cavernous sinus or internal carotid artery may occur.[32] All of the areas of involvement must be understood in order to plan the extent of surgical debridement.
Magnetic resonance imaging (MRI) of the facial sinuses and brain is superior to a CT scan in assessing the degree of tissue invasion and need for ongoing surgery.
While chest radiography is often the initial test performed, its sensitivity and specificity for mucormycosis are low. Nonenhanced high-resolution CT scanning is the imaging modality of choice.[14] The most common findings include pleural effusion, nodules, consolidation, and ground-glass opacities.[23] With disease progression, consolidation can become multilobar. The reverse halo sign (ie, a nodule with central ground-glass opacity and a ring of peripheral consolidation) strongly suggests pulmonary mucormycosis and is rarely seen in invasive aspergillosis.[33] The halo sign (ie, a nodule surrounded by ground-glass opacity) represents a lung infarct surrounded by alveolar hemorrhage; it is associated with invasive mold infections but can be present in bacterial or viral infections and noninfectious lung disease (eg, Wegener granulomatosis, sarcoidosis, malignancy).[14] Other findings such as the air crescent sign and hypodense sign are less specific and may occur in later stages. See the images below.
View Image | Chest computed tomography (CT) scan showing pulmonary mucormycosis with left basal consolidation and widespread nodules due to Rhizopus oryzae infecti.... |
View Image | Chest computed tomography (CT) scan showing pulmonary mucormycosis with left basal consolidation and widespread nodules due to Rhizopus oryzae infecti.... |
In gastrointestinal (GI) disease, abdominal CT scans may show a mass associated with the GI tract. Esophagogastroduodenoscopy (EGD) may show areas of tissue necrosis amenable to biopsy.
CT scanning or MRI of the central nervous system may reveal abscesses (especially in the setting of intravenous drug use) or extension of rhinocerebral disease into the brain. Cavernous and, less commonly, sagittal sinus thrombosis may also be seen. See image below.
View Image | Brain MRI (sagittal view) in a patient with uncontrolled diabetes who presented with progressive right eye pain and facial swelling. He underwent mult.... |
Biopsy of the involved tissue is the most critical means of establishing a diagnosis of mucormycosis. A rapid histologic assessment of a frozen tissue section should be performed in order to promptly institute surgical and medical management for the infection.
Biopsy of necrotic tissue may be obtained from nasal, palatine, lung, cutaneous, gastrointestinal (GI), or abscess wall site.
Stains of fixed tissues with hematoxylin and eosin (H&E) or specialized fungal stains, such as Grocott methenamine-silver (see the following image) or periodic acid-Schiff (PAS) stains, show pathognomonic broad (typically 6- to 25-µm diameter), irregular, ribbonlike, nonseptate (or sparsely septate) hyphae with irregular branching occurring at 45-90º.[34] Vascular invasion and necrosis are the characteristic consequences of the infective process. Thus, neutrophil infiltration, vessel invasion, and tissue infarction are often observed. A granulomatous reaction may also be seen.
View Image | Histologic findings from an immunocompetent man who sustained a high-pressure water jet injury, resulting in rhinocerebral mucormycosis. Traumatic ino.... |
Culture of biopsy samples is generally required to determine the species of Mucorales. Do not crush or grind the specimen, because the nonseptate hyphae are prone to damage. Growth usually occurs in 2-3 days. The genus and species are determined via examination of the fungal morphology (ie, the presence and location of the rhizoids). Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) can also provide rapid and accurate identification at the species level but requires a reference database. 18s ribosomal RNA (rRNA) sequencing may provide genus-level identification, even if tissue damage precludes fungal growth.[14]
Patients with mucormycosis should be treated in a tertiary care center with subspecialty units experienced in the management of this condition and its underlying risk factors. Correction of the underlying abnormality, prompt initiation of liposomal amphotericin B therapy, and surgical resection are critical.[1, 31, 35]
Other important considerations in medical management include the following:
The use of contaminated bandages and other dressings has caused cutaneous mucormycosis. Failure to examine areas under dressings or to recognize the significance of deterioration in preexisting wounds may produce severe cutaneous and, ultimately, disseminated disease. Place patients with severe prolonged neutropenia in rooms equipped with high-efficiency particulate air (HEPA) filters, when feasible. Secondary prophylaxis is often used after therapy among patients who remain immunocompromised.[1]
No prospective comparative studies of the primary treatment of mucormycosis have been performed, largely because of the rarity of this disease. In current practice, amphotericin B and isavuconazole are the two antifungal agents licensed by the US Food and Drug Administration (FDA) for the primary therapy of mucormycosis. First-line treatment is with an amphotericin derivative, preferably the liposomal form of amphotericin B to minimize nephrotoxicity. Other options include amphotericin B deoxycholate, isavuconazole, and posaconazole.
Although some reports have described a combination of different classes of antifungal agents, trials are needed to determine the efficacy of this approach.[36] Potential advantages would include more rapid fungicidal activity and lower risk of resistance. Potential disadvantages would include the risk for antagonism, additive or synergistic toxicity, more drug-drug interactions, and higher cost.[37]
Amphotericin B has proven efficacy in the treatment of mucormycosis. At the present time, the liposomal formulation (AmBisome) is the drug of choice based on efficacy and safety data.[38, 39, 40] Lipid preparations of amphotericin B are used at 5 mg/kg/d.[1] Some have used doses of up to 7.5-10 mg/kg/d to treat mucormycosis, especially CNS disease[38] . The use of higher doses, however, has been associated with rates of nephrotoxicity up to 40% without a concomitant mortality benefit.[31, 36, 41, 42]
Amphotericin B deoxycholate can also be used to treat mucormycosis, particularly when other formulations prove too costly. The typical dose is 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. This is of particular concern since many patients who develop mucormycosis have preexisting renal disease (eg, diabetics, transplant recipients). Monitor the renal function of patients taking amphotericin B; doubling of serum creatinine over the baseline levels is an indication for changing to liposomal amphotericin B.
In addition, careful monitoring and repletion of serum electrolytes (eg, potassium, phosphorus, magnesium) should be performed when administering any formulation of amphotericin B.
Isavuconazole (Cresemba) is a novel triazole antifungal agent that was approved for the treatment of mucormycosis in March 2015. The prodrug isavuconazonium sulfate is rapidly metabolized by serum butylcholinesterase to the active form, isavuconazole (ISZ).[34]
The efficacy of isavuconazole in the treatment of invasive mucormycosis has not been evaluated in randomized controlled trials because of the rarity of this disease. The approval of this medication was based on a noncomparative, single-arm, open-label, matched, case-control trial (VITAL). Of 149 patients enrolled, 37 had proven (86%) or probable (14%) mucormycosis. Twenty-one patients received primary treatment with ISZ, while 11 patients received ISZ salvage therapy; 5 were intolerant to other antifungals. Controls treated with amphotericin (67% liposomal, 12% lipid complex, 21% deoxycholate) were matched from the Fungiscope Registry. Isavuconazole- and amphotericin-treated patients had similar day-42 weighted all-cause mortality at 33% and 41%, respectively. Patients received ISZ for a median of 84 days versus 18 for amphotericin, suggesting more favorable tolerability.[43]
Isavuconazole offers several advantages over other triazoles (ie, posaconazole, voriconazole), apart from its wider spectrum of antifungal activity. The drug has excellent oral bioavailability not reliant on food intake or gastric pH and is also available in an intravenous formulation, which does not contain the nephrotoxic solubilizing agent cyclodextrin. Switching between oral and IV forms does not require dose adjustment. ISZ displays linear and predictable pharmacokinetics with minimal CYP3A4 interactions, reducing or eliminating the need for therapeutic drug monitoring. Unlike voriconazole, ISZ does not cause phototoxicity, increased risk of squamous cell carcinoma, or visual disturbance. The clinical significance of ISZ-related QTc shortening is unknown, but it is reasonable to avoid this medication in patients with familial short QT syndrome and to avoid co-administrating with sodium channel–blocking antiepileptics.[44]
Given the highly variable, species-dependent susceptibility pattern of the Mucorales to isavuconazole, clinical susceptibility testing may be indicated in some situations.[45]
Posaconazole, another triazole antifungal, has been shown to be superior to fluconazole or itraconazole as prophylaxis against invasive mold infection (both aspergillosis and mucormycosis) in patients with hematologic malignancy who have neutropenia or GVHD. The number needed to treat (NNT) to prevent one fungal infection was 27 and to prevent one death was 35.[46]
Posaconazole can be used for off-label salvage treatment of mucormycosis in patients intolerant to amphotericin B. Issues with the absorption of the oral suspension of posaconazole, particularly decreased absorption in the setting of proton pump inhibitor (PPI) or antimotility agent (eg, metoclopramide) use have been overcome with the introduction of a delayed-release tablet formulation.[38, 34] An intravenous formulation is also available. Therapeutic drug monitoring may still be considered in patients on potent CYP450 inhibitors.
Several case reports have discussed the use of posaconazole,[32, 47] including as salvage therapy.[48] A review of 96 patients treated with posaconazole found that complete response was achieved in 62 (64.6%), partial response in 7 (7.3%) patients, and stable disease in 1 (1%), with an overall mortality of 24% (no data for 3 patients).[49] Rickerts et al reported that liposomal amphotericin B plus posaconazole was successful in the treatment of disseminated mucormycosis in a patient who could not undergo surgery; however, the benefit of dual antifungal therapy is unclear (see below).[50, 36]
Posaconazole has also been used as step-down therapy after the initial administration and control of the disease with liposomal amphotericin B.[51, 52]
Other azoles (ie, fluconazole, voriconazole) are ineffective against Mucorales species. With the use of voriconazole prophylaxis in high-risk patients, such as transplant recipients, mucormycosis has been reported.[53, 54, 55]
Most Mucorales species show moderate in vitro resistance to the echinocandins; these agents cannot be used alone in the treatment of mucormycosis.[15] Animal and limited clinical data have suggested that combination therapy with amphotericin and an echinocandin may improve survival.[38, 39, 56, 57, 58] However, a recent retrospective cohort study of combination liposomal amphotericin B (L-AmB) with posaconazole, L-AmB with echinocandins, and posaconazole with echinocandins showed no differences in mortality between monotherapy and combination treatment groups.[59] The in vitro combinations of isavuconazole with micafungin or amphotericin resulted in a range of interactions, some concentration-dependent, ranging from antagonism to synergy against various Mucorales.[60]
Further clinical trials are needed before antifungal combination therapy can be definitively recommended.
Debridement of necrotic tissue in combination with medical therapy is mandatory for patient survival. In rhinocerebral disease, surgical care includes drainage of the sinuses and may require excision of the orbital contents and involved brain (see the following image). Repeated surgery may be required, especially for rhinocerebral mucormycosis.
Excise pulmonary lesions if they are localized to a single lobe, excise cutaneous lesions entirely, and resect any GI masses.
View Image | An immunocompetent man who sustained a high-pressure water jet injury, resulting in rhinocerebral mucormycosis. Traumatic inoculation of Apophysomyces.... |
Hyperbaric oxygen therapy after surgical debridement has been used, especially in cases of cutaneous disease and rhinocerebral disease in diabetics, but its effectiveness has not been extensively studied. Treatment of mucormycosis is not currently one of the approved uses of hyperbaric oxygen.[47, 61] High oxygen concentrations may improve neutrophil function, inhibit the growth of Mucorales, and improve wound healing.
Colony-stimulating factors have been used to enhance immune responses, specifically in neutropenic patients, as have interferon-gamma and white blood cell transfusions. The usefulness of these interventions is unclear.
Finally, the use of iron chelators without xenosiderophore activity (eg, deferasirox) has been described in case reports.[61] Older iron chelators, namely deferoxamine, can be exploited as an iron source by Rhizopus, thereby increasing the risk of mucormycosis.[34] Newer agents such as deferasirox were hypothesized to decrease the risk of mucormycosis via iron starvation; however, they have not proven clinically efficacious.[62] In an immunosuppressed murine model of pulmonary mucormycosis, a combination of deferasirox with posaconazole increased the AUC/MIC of posaconazole but failed to demonstrate improved efficacy over monotherapy.[63] In the DEFEAT study, 20 patients with mucormycosis were randomly assigned to L-AmB plus deferasirox or L-AmB plus placebo; the deferasirox arm had a higher 90-day mortality rate.[64, 65]
Patient survival from mucormycosis requires rapid diagnosis and aggressive coordinated medical and surgical therapy. To that effect, consultations with various specialists are critical.
Infectious disease consultation is warranted for management of antifungal therapy and coordination of medical care.
Surgical specialty consultations depend on the location of disease, as follows:
In addition, endocrinology consultation may be necessary for the management of unstable diabetes, hematology/oncology consultation may be needed for the management of issues related to underlying malignancy, and surgical intensive care unit (SICU) consultation is important for perioperative care.
Ongoing clinical surveillance and diagnostic imaging are required to ensure complete resolution of mucormycosis and to detect relapse.
The duration of therapy is highly individualized and should encompass the resolution of associated symptoms and findings, normalization of radiographic findings (with the exception of radiographic findings thought to be the result of postinflammatory or postoperative scar formation), negative cultures from the affected site, and resolution of immunosuppression.[1, 31, 35]
Successful courses of amphotericin B typically last 4-6 weeks. Primary or salvage isavuconazole therapy may be continued for several months given its higher tolerability compared with amphotericin. Repeated surgical debridement of necrotic tissue identified by follow-up head computed tomography (CT) scan or magnetic resonance imaging (MRI) is often indicated.
For patients who successfully complete therapy for mucormycosis and who subsequently require immunosuppressive treatments (eg, chemotherapy in a patient with cancer), whether daily oral posaconazole or isavuconazole should be given as secondary prophylaxis against disease relapse is unknown. Evidence-based data on the best strategy for secondary prophylaxis are not currently available.[1] Owing to their broad spectrum of anti-mold activity, safety, tolerability and oral bioavailability, there is considerable potential for inappropriate empiric and prophylactic use of the newer triazole antifungals.[44]
Educate patients about the signs of disease, such as facial swelling and black nasal discharge, and instruct patients to present promptly for evaluation if these signs occur.
The two main classes of antifungal medications used to treat mucormycosis are the polyenes (amphotericin formulations) and triazoles (isavuconazole and posaconazole). Amphotericin B and isavuconazole are the two agents currently FDA approved for the primary therapy of mucormycosis. Posaconazole can be used off-label for salvage treatment in patients intolerant to amphotericin B. It has also been used as step-down therapy after initial control of the disease with amphotericin.[51, 52]
In patients with hematologic malignancy, posaconazole is superior to other triazoles as prophylaxis for invasive mold infection. Isavuconazole is a novel triazole antifungal agent with many advantages, including excellent oral bioavailability, linear and predictable pharmacokinetics, and minimal CYP450 interactions.[44] Owing to its safety, tolerability, and comparable efficacy to amphotericin B,[43] isavuconazole is promising as a primary and salvage therapy. Further study is needed prior to its use as primary mold prophylaxis in the setting of prolonged neutropenia.
Echinocandin agents, including anidulafungin, caspofungin, and micafungin, competitively inhibit the beta-1,3-D-glucan synthase enzyme complex. In Candida species, beta-glucan depletion causes cell lysis via loss of resistance to osmotic force; in Aspergillus, it is fungistatic owing to impaired growth at hyphal branching points. Echinocandins have minimal activity against the Mucorales, which contain little or no beta-1,3-D-glucan. Some studies have suggested combination therapy with amphotericin and an echinocandin may improve survival; however, a more recent retrospective study showed no such mortality benefit. There is no current evidence-based recommendation for the addition of an echinocandin to amphotericin B or isavuconazole for the treatment of mucormycosis.
The benefit of combination therapy with different classes of antifungals (including echinocandins) is uncertain. Despite advances in medical management, surgical evaluation is essential in the management of mucormycosis, and overall mortality rates remain high.
See the Treatment section for further discussion of individual antifungal agents.
Clinical Context: Consists of a mixture of phosphatidylcholine, cholesterol, and distearoyl phosphatidylglycerol that arrange into amphotericin B–containing unilamellar vesicles in aqueous media. First-line therapy for mucormycosis at 5 mg/kg/d. Owing to decreased risk of nephrotoxicity at this dose, it can be used in the setting of preexisting renal dysfunction and when nephrotoxicity develops during amphotericin B deoxycholate therapy. Careful electrolyte monitoring and replacement is required.
Clinical Context: Amphotericin B lipid complex is amphotericin B in phospholipid complexed form. This is an alternate therapy to liposomal amphotericin B.
Clinical Context: Less commonly used than the lipid formulations because of higher rates of nephrotoxicity but less costly and more widely available. The typical dose is 1-1.5 mg/kg/d. The total dose given over the course of therapy is usually 2.5-3 g.
These agents bind irreversibly to ergosterol within the fungal cell membrane. This binding results in disruption of membrane integrity, leakage of intracellular components, and, ultimately, cell death.
Clinical Context: Novel triazole approved in 2015 for the treatment of mucormycosis. It has equivalent oral and IV bioavailability and a favorable safety/tolerability profile. The oral prodrug isavuconazonium sulfate is rapidly converted to the active isavuconazole moiety. Initial dosing is isavuconazonium sulfate 372 mg (isavuconazole 200 mg) every 8 hours for 6 doses, followed by maintenance with 372 mg once daily.
Clinical Context: Used off-label for salvage therapy in patients intolerant to amphotericin B or as step-down therapy after initial polyene treatment. Administered as one 300-mg tablet twice on day 1 followed by 300 mg orally once daily with or without food. The delayed-release tablet formulation is preferred over the oral suspension because of its more reliable absorption. An intravenous formulation is also available.
These agents inhibit the cytochrome P450-dependent 14-alpha-lanosterol demethylase of the fungal cell membrane. Toxic cell membrane sterols accumulate and ergosterol production is inhibited, leading to impaired growth and replication and, ultimately, cell death.
The right eye of an immunocompetent man who sustained a high-pressure water jet injury, resulting in rhinocerebral mucormycosis. Traumatic inoculation of Apophysomyces elegans was the pathogenetic mechanism. Chemosis is shown in this photograph. Internal and external ophthalmoplegia, no light perception, and afferent pupil defect were present, which is consistent with orbital apex syndrome. Courtesy of A Allworth, MD, Brisbane, Australia.
An immunocompetent man who sustained a high-pressure water jet injury, resulting in rhinocerebral mucormycosis. Traumatic inoculation of Apophysomyces elegans was the pathogenetic mechanism. A surgical field of this patient is shown. Excision of the right orbit, maxillary antrum, nasal cavity, sphenoid sinus, and infratemporal fossa has taken place. The tissue was infarcted. Courtesy of A Allworth, MD, Brisbane, Australia.
Chest computed tomography (CT) scan showing pulmonary mucormycosis with left basal consolidation and widespread nodules due to Rhizopus oryzae infection. The patient was receiving cytotoxic chemotherapy for myelodysplastic syndrome and had iron overload from numerous blood transfusions. This CT scan of the patient shows resolution of pulmonary mucormycosis after 5 months of antifungal treatment.
Brain MRI (sagittal view) in a patient with uncontrolled diabetes who presented with progressive right eye pain and facial swelling. He underwent multiple surgeries to control rhinocerebral Mucor infection, including partial right frontal lobectomy and right orbital exenteration. He was treated with amphotericin B and his diabetes mellitus was controlled. The disease did not progress, and long-term isavuconazole therapy was initiated for salvage/maintenance therapy.
Histologic findings from an immunocompetent man who sustained a high-pressure water jet injury, resulting in rhinocerebral mucormycosis. Traumatic inoculation of Apophysomyces elegans was the pathogenetic mechanism. Findings show the typical Mucorales hyphae on Grocott methenamine-silver staining. The hyphae are the dark structures with budlike, right-angle hyphae. Courtesy of A Allworth, MD, Brisbane, Australia.
An immunocompetent man who sustained a high-pressure water jet injury, resulting in rhinocerebral mucormycosis. Traumatic inoculation of Apophysomyces elegans was the pathogenetic mechanism. A surgical field of this patient is shown. Excision of the right orbit, maxillary antrum, nasal cavity, sphenoid sinus, and infratemporal fossa has taken place. The tissue was infarcted. Courtesy of A Allworth, MD, Brisbane, Australia.
The right eye of an immunocompetent man who sustained a high-pressure water jet injury, resulting in rhinocerebral mucormycosis. Traumatic inoculation of Apophysomyces elegans was the pathogenetic mechanism. Chemosis is shown in this photograph. Internal and external ophthalmoplegia, no light perception, and afferent pupil defect were present, which is consistent with orbital apex syndrome. Courtesy of A Allworth, MD, Brisbane, Australia.
An immunocompetent man who sustained a high-pressure water jet injury, resulting in rhinocerebral mucormycosis. Traumatic inoculation of Apophysomyces elegans was the pathogenetic mechanism. A surgical field of this patient is shown. Excision of the right orbit, maxillary antrum, nasal cavity, sphenoid sinus, and infratemporal fossa has taken place. The tissue was infarcted. Courtesy of A Allworth, MD, Brisbane, Australia.
An immunocompetent man who sustained a high-pressure water jet injury, resulting in rhinocerebral mucormycosis. Traumatic inoculation of Apophysomyces elegans was the pathogenetic mechanism. Picture of the patient after successful treatment with repeated surgical debridement and high-dose liposomal amphotericin B. Courtesy of A Allworth, MD, Brisbane, Australia.
Histologic findings from an immunocompetent man who sustained a high-pressure water jet injury, resulting in rhinocerebral mucormycosis. Traumatic inoculation of Apophysomyces elegans was the pathogenetic mechanism. Findings show the typical Mucorales hyphae on Grocott methenamine-silver staining. The hyphae are the dark structures with budlike, right-angle hyphae. Courtesy of A Allworth, MD, Brisbane, Australia.
Chest computed tomography (CT) scan showing pulmonary mucormycosis with left basal consolidation and widespread nodules due to Rhizopus oryzae infection. The patient was receiving cytotoxic chemotherapy for myelodysplastic syndrome and had iron overload from numerous blood transfusions. This CT scan of the patient shows resolution of pulmonary mucormycosis after 5 months of antifungal treatment.
Brain MRI (sagittal view) in a patient with uncontrolled diabetes who presented with progressive right eye pain and facial swelling. He underwent multiple surgeries to control rhinocerebral Mucor infection, including partial right frontal lobectomy and right orbital exenteration. He was treated with amphotericin B and his diabetes mellitus was controlled. The disease did not progress, and long-term isavuconazole therapy was initiated for salvage/maintenance therapy.