Mucormycosis is an
infection caused by a group of filamentous molds within the order Mucorales.
Infections may result from ingestion of contaminated food, inhalation of spores into the nares or lungs, or inoculation into disrupted skin or
wounds. In developed countries,
mucormycosis occurs primarily in severely immunocompromised hosts (e.g., those with
hematological malignancies,
organ transplantation,
neutropenia, autoimmune disorders, or other impairments in immunity). Only 6 to 10% of cases occur in subjects with no underlying disease. In contrast, in developing countries, most cases of
mucormycosis occur in persons with poorly controlled
diabetes mellitus or in immunocompetent subjects following
trauma.
Mucormycosis exhibits a marked propensity to invade blood vessels, leading to
thrombosis,
necrosis, and
infarction of tissue. Mortality associated with invasive
mucormycosis is high (> 30-50%), with 90% mortality associated with disseminated disease. Mortality rates are much lower, though still significant (10-30%), among patients with localized cutaneous disease.The diagnosis of
mucormycosis relies upon histopathology and culture. Blood tests are of limited diagnostic value. Even with disseminated
disease, blood cultures are usually negative. Mucorales have a distinct histological appearance, with irregular, nonseptate hyphae that branch at right angles. Cultures and/or polymerase chain reaction (PCR) are important to identify the genera.Based on anatomic localization,
mucormycosis can be classified as one of six forms: (1) rhino-orbital-cerebral
mucormycosis (ROCM), (2) pulmonary, (3) cutaneous, (4) gastrointestinal (GI), (5) disseminated, and (6)
mucormycosis of uncommon sites. Among diabetics, ROCM is the most common clinical presentation, whereas lung involvement is uncommon. In contrast, among organ transplant recipients or patients with
hematological malignancies (HemeM), pulmonary and disseminated diseases are most common.
Mucormycosis can progress rapidly, and delay in initiation of treatment by even a few days markedly worsens outcomes.Due to the rarity of
mucormycosis, randomized controlled therapeutic trials have not been performed.
Lipid formulations of
amphotericin B (LFAB) are the mainstay of
therapy, but the newer
triazoles,
posaconazole (POSA) and
isavuconazole (ISAV) (the active component of the
prodrug isavuconazonium sulfate), may be effective in patients refractory to or intolerant of LFAB. Early surgical
debridement or excision plays an important adjunctive role. Additional studies are required to assess the optimal
duration of therapy as well as the specific roles of LFAB and the
triazoles in the treatment of
mucormycosis.