eMedicine Specialties > Pediatrics: General Medicine > Infectious Disease
Mucormycosis
Updated: Nov 20, 2008
Introduction
Background
Mucormycosis usually refers to fungal infections in immunosuppressed hosts caused by ubiquitous molds found in organic matter and soil. Such molds belong to the order Mucorales. The infections they cause manifest in the rhinocerebral, pulmonary, cutaneous, GI, disseminated, and central nervous systems. Mucormycosis is often life threatening. Therefore, prompt diagnosis and institution of antifungal therapy are vital, as is appropriate management of the underlying disease process. In addition to cases involving immunosuppressed children, mucormycosis has also been observed in neonates (especially premature infants), patients with burns, and children with a history of incidental trauma.
Pathophysiology
The fungus gains entry into the body through the nasopharynx. It can be inhaled into the lungs, or it can extend to the sinuses, orbit, and brain. The occurrence of mucormycosis depends on host immunity, but the mechanisms of increased susceptibility in certain hosts remain perplexing. Regardless of the anatomic site is involved, characteristic histopathologic findings include angioinvasion with subsequent tissue infarction and necrosis leading to tissue destruction.
The fungal pathogens that cause mucormycosis belong to the class Zygomycetes and the order Mucorales. Rhizopus species are the agents most commonly isolated in mucormycosis, followed by Rhizomucor species, Absidia corymbifera, Apophysomyces elegans, Cunninghamella bertholletiae, Mucor species, and Saksenaea vasiformis.
Upon microscopic examination, fungi of the Mucorales order are characterized by aseptate hyphae, which vary in width up to 50 µm. These hyphae are broad and branch from the main hyphal trunk; they are often angled 90°. Identification of most of the Zygomycetes is accomplished by observing the morphology of the sporangia, such as presence or absence of the columellae and apophyses, arrangement and number of sporangiospores, and absence or presence of rhizoids.
Frequency
United States
Mucormycosis is most common in immunocompromised hosts, although cases in immunocompetent patients are also reported. Underlying diseases, such as diabetes mellitus and malignancy, are risk factors. Aside from these, environmental spore exposure (from exposure to construction activity) has also led to clinical cases of mucormycosis. Other cases have been reported in patients with traumatic skin injury (eg, associated with the use of nonsterile adhesive tape or with use of tongue depressors as splints in neonates). Exposure to voriconazole, which is not active against mucormycosis, is noted to be a risk factor in patients with cancer.
Mortality/Morbidity
The overall mortality rate in adults is 50%, though survival rates higher than this have been reported. Survival rates largely depend on early diagnosis and resolution of the patient's underlying condition.
Race
No racial predilection is reported.
Sex
No sexual predilection is reported.
Age
Most cases of mucormycosis occur in immunosuppressed adults. In a pooled review, Kline described 41 cases of rhinocerebral mucormycosis occurring in children and adolescents aged 2 months to 18 years.1 About 49% of cases were found in patients with diabetes mellitus, and 15% of cases were found in those with leukemia. Four of the 41 children (10%) had no predisposing conditions.
Clinical
History
Symptoms of mucormycosis vary depending on the involved anatomic site.
- The most common signs and symptoms of rhinocerebral mucormycosis are altered mental status, fever, and pain and swelling over the involved site. Most of these findings occur in patients with diabetic ketoacidosis.
- Persistence of altered mental status after metabolic abnormalities are corrected, especially in patients with diabetic ketoacidosis, should alert the physician to consider mucormycosis involving the CNS.
- Fever, dyspnea, hemoptysis, and cough are observed in patients with pulmonary mucormycosis.
- Unexplained or persistent fever in a patient who has immunosuppression and who is receiving broad-spectrum antibiotics should alert the clinician to look for possible foci of mucormycosis.
- Severe headache and abdominal pain can be manifestations of rhinocerebral and GI mucormycosis, respectively.
- GI mucormycosis is mostly encountered in premature neonates and in patients with malnutrition. Severe malnutrition is an independent risk factor.
Physical
- A black eschar of the nasal mucosa or palate usually is a hallmark sign of rhinocerebral mucormycosis. It is a sign of deep infection and tissue destruction of the nasal mucosa. This finding on physical examination should prompt biopsy and empiric treatment.
- A black eschar on the skin of a patient who is immunocompromised should also prompt skin biopsy (see Media file 1).
- Loss of extraocular muscular function, along with proptosis and cranial nerve dysfunction of cranial nerves V and VII, are signs of neurologic involvement in mucormycosis. Several other cranial nerves, such as cranial nerves I, III, and IV, can also be involved.
- Progressive cellulitis of skin lesions with gangrene and necrosis is another concern in cutaneous mucormycosis.
Causes
- Risk factors in adults and children include diabetes mellitus (especially with ketoacidosis), which is the underlying condition most commonly associated with mucormycosis. This is probably due to diminished function of phagocytes at low pH.
- Other individuals at risk include patients with malignancy, those with protein calorie malnutrition, those with skin breakdown due to burns, those with trauma or those who are undergoing surgery, those with acute and chronic renal disease, and those with hematologic disease who are receiving deferoxamine.
- Hospital-acquired mucormycosis has been reported. In a review of literature of 26 hospitalized, posttruamatic patients with mucormycosis, approximately 57% were females and two thirds had comorbidities (ie, diabetes mellitus, leukemia, immunosuppression); diabetes was noted in 6 patients.2 In hospitalized patients with cannula, wound or occlusive dressings should be closely watched for erythema or necrosis.
- Patients with immunosuppression due to acquired immunodeficiency syndrome (AIDS), organ transplantation, neutropenia, or steroid therapy are also at risk.
- Neonates, especially those born prematurely, can be at risk. Unusual incidents of neonatal mucormycosis might have occurred when patients were exposed to contaminated surfaces, such as bandages, tongue depressors used as arm splints, or cardiac-monitor leads.
- Also, see Frequency.
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References
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Further Reading
Keywords
mucormycosis, Mucorales infection, fungal infection, Rhizopus species infection, Rhizomucor species infection, Absidia corymbifera infection, A corymbifera infection, Apophysomyces elegans infection, A elegans infection, Cunninghamella bertholletiae infection, C bertholletiae infection, Mucor species infection, Saksenaea vasiformis infection, S vasiformis infection, burns, trauma, diabetes mellitus, leukemia, diabetic ketoacidosis, malnutrition
