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Gastrointestinal Mucormycosis: An Elusive, Unusual, and Severe Opportunistic Mycosis.

Year: 2009
Type: article
Abstract: This commentary provides instructive information regarding gastrointestinal mucormycosis, a rare disease that requires a high index of suspicion for an early diagnosis. In the case reported by Azhar and colleagues, the finding of a large hypoechoic mass in the left upper quadrant that was determined to be hemoperitoneum triggered further diagnostic tests, including exploratory laparotomy.1 The final diagnosis was a perforated gastric ulcer and peritonitis with findings suggestive of mucormycosis in the Gomori methenamine silver stain, complicated with a polymicrobial intra-abdominal infection. The presence of hemorrhage in the peritoneum was due to a perforated gastric ulcer that could have been caused by a necrotizing angioinvasion by either the Zygomycete itself2,3 or as a complication of alcohol abuse (ie, erosive gastritis). Tissue infarction and hemorrhage are pathologic hallmarks in patients with mucormycosis.3 The classic groups at risk for mucormycosis are patients who undergo stem-cell transplantation, patients with prolonged and profound neutropenia, patients with poorly controlled diabetes, patients with iron overload, and patients previously exposed to voriconazole.2,4 Factors previously identified specifically for gastrointestinal mucormycosis include infant prematurity, severe malnutrition, pica, severe systemic illnesses, and extremes of age.2 The patient treated by Azhar and coworkers had some degree of immunodeficiency in light of his history of diabetes and alcohol abuse. His history of tuberculosis also suggests the possibility of deficiency in T-cell immunity. For mucormycosis, early diagnosis and adequate staging of the infection are vital to guide prompt and effective therapy, as dissemination is common. The diagnosis of this invasive fungal infection remains challenging. The imaging findings are nonspecific,2 and there are no antigen-based or molecular biology diagnostic examinations for this entity.5 Zygomycetes are fastidious fungi, and cultures are negative in at least 40% of cases.6 Not uncommonly, histopathologic identification is the only way to specifically diagnose this infection.2 However, even histopathologic evidence of invasive fungal infection in tissue could not provide a definite identification of the Zygomycete.2,7 Some hyalohyphomycetes such as Fusarium species or Scedosporium species occasionally have indistinguishable appearance in tissues.2,7 In an effort to improve the low yield of cultures, a recent study improved the culture of the Zygomycete by simulating its micro-anaerobic environment to allow for better in-vitro growth.8 Besides a timely diagnosis, effective treatment of mucormycosis requires the aggressive control of predisposing factors, extensive surgical debridement of infected tissue, and prompt administration of systemic antifungal therapy.2 A combination of different therapeutic approaches such as surgery and systemic antifungal therapy is commonly used, as in the case reported by Azhar and associates. Although there are no prospective randomized controlled studies defining the optimal antifungal approach for mucormycosis, amphotericin B has been the cornerstone of therapy.9 However, it is our opinion that lipid formulations of amphotericin B are safer for long-term treatments and should represent first-line therapy.2,10 Another option is the use of posaconazole, the only triazole that appears to be active against this invasive fungus.2,11,12 Although the results are controversial in animal studies, clinical data from an open-label study and from a retrospective review suggest that posaconazole may be an effective treatment option as salvage therapy.11,12 The main limitation of posaconazole is its availability as only an oral preparation. Multiple factors affect the oral absorption of posaconazole as well as the time required to reach an adequate plasma concentration.2,13 Monitoring plasma posaconazole levels to document its absorption is prudent. Further studies are needed to define the use of posaconazole alone, sequentially (as in this report), or in combination with a lipid formulation of amphotericin B. As mentioned in the case by Azhar and associates, the oral route was the main limitation in their critically ill patient who underwent concomitant surgical treatment. Recent advances in adjunctive therapy of mucormycosis include the use of hyperbaric oxygen therapy and the use of novel iron chelators such as deferiprone and deferasirox.2 Hyperbaric therapy has been beneficial as adjunct therapy of surgery and antifungal therapy in selected patients.14,15 The above-named iron chelators have been reported to be beneficial as an adjunct therapy to systemic antifungal therapy,16,17 particularly in patients with diabetic ketoacidosis, though further clinical trials are still in progress. In conclusion, there are several unanswered questions regarding the epidemiology, pathophysiology, diagnosis, and management of gastrointestinal mucormycosis. This entity requires a low threshold of clinical suspicion for early diagnosis and prompt, effective therapy, usually a combination of surgical therapy and systemic antifungal therapy.
Source: PubMed
Language: English
Field: Medicine
Open Access status: green
OpenAlex ID: W53789728
FWCI:
Cites: 14
Cited by: 1
Related to: 10