Colonic Mucormycosis Causing Massive Lower Gastrointestinal Bleeding: A Case Report


 BackgroundLower gastrointestinal bleeding (LGIB) is very common in the hospital setting. Most bleedings stop spontaneously, but rare infectious causes of LGIB may lead to rapid and serious complications if left untreated.Case PresentationWe described a young man with poorly controlled Type I Diabetes Mellitus and chronic alcohol abuse who presented with acute altered mental status. During his hospitalization for treatment of diabetic ketoacidosis, acute renal failure, and sepsis, he suddenly developed massive hematochezia of 1500ml. Colonoscopy was done and a deep ulcer covered with mucus with peripheral elevation was noted at the transverse colon. Biopsy of the ulcer later revealed nonpigmented, wide (5-20 µm in diameter), thin-walled, ribbon-like hyphae with few septations and right-angle branching suggestive of mucormycosis demonstrated by Periodic acid–Schiff stain. He received two months of antifungal treatment. Follow up colonoscopy post-treatment was normal with no ulcer visualized.ConclusionsEarly diagnosis and treatment of gastrointestinal (GI) mucormycosis infection is critical but can be challenging, especially in the setting of massive hematochezia. Therefore, clinical awareness for immunocompromised patients and prompt antifungal prophylaxis in cases with high suspicion of infection are essential.


Abstract Background
Lower gastrointestinal bleeding (LGIB) is very common in the hospital setting. Most bleedings stop spontaneously, but rare infectious causes of LGIB may lead to rapid and serious complications if left untreated.

Case Presentation
We described a young man with poorly controlled Type I Diabetes Mellitus and chronic alcohol abuse who presented with acute altered mental status. During his hospitalization for treatment of diabetic ketoacidosis, acute renal failure, and sepsis, he suddenly developed massive hematochezia of 1500ml.
Colonoscopy was done and a deep ulcer covered with mucus with peripheral elevation was noted at the transverse colon. Biopsy of the ulcer later revealed nonpigmented, wide (5-20 µm in diameter), thin-walled, ribbon-like hyphae with few septations and right-angle branching suggestive of mucormycosis demonstrated by Periodic acid-Schiff stain. He received two months of antifungal treatment. Follow up colonoscopy post-treatment was normal with no ulcer visualized.

Conclusions
Early diagnosis and treatment of gastrointestinal (GI) mucormycosis infection is critical but can be challenging, especially in the setting of massive hematochezia. Therefore, clinical awareness for immunocompromised patients and prompt antifungal prophylaxis in cases with high suspicion of infection are essential.

Background
Lower gastrointestinal bleeding (LGIB) presenting as hematochezia is very common in the hospital setting. Most cases of LGIB stop spontaneously, but acute severe bleeding can be life-threatening, especially in patients with comorbidities. To improve diagnostic and therapeutic yields, early colonoscopy is recommended for patients with acute LGIB(1), The most common etiologies of LGIB include diverticulosis, angiodysplasia, colorectal neoplasms, hemorrhoids, and rectal ulcer. Other causes such as in ammatory bowel disease, proctitis are also important differential diagnoses. In immunocompromised patients, opportunistic infections of the GI tract resulting in massive LGIB have been reported in previous literature. These include viral infections such as cytomegalovirus colitis (2), bacterial infections such as tuberculosis (3), and fungal infections such as aspergillosis(4) and mucormycosis. Among these infections, mucormycosis causing LGIB has been the least reported.
Presentations of intestinal mucormycosis reported in literature have been non-speci c, ranging from afebrile abdominal pain to severe intestinal perforation. In the few reported cases of mucormycosis presenting as severe LGIB, almost all patients died despite treatment. Delayed diagnosis was often identi ed as the fundamental reason to mortality. We described a case of GI mucormycosis presenting as massive hematochezia in an immunocompromised patient with diabetic ketoacidosis (DKA). Prompt diagnosis with colonoscopy and antifungal treatment resulted in satisfactory outcome.

Case Presentation
A 28-year-old man was brought to the Emergency Department (ED) by his father due to acute altered mental status and shortness of breath since earlier that morning. His medical history was signi cant of poorly controlled Type I Diabetes Mellitus with multiple hospitalizations due to diabetes ketoacidosis (DKA), severe chronic alcohol abuse for 8 years, and chronic pancreatitis. He was also diagnosed with nasopharyngeal carcinoma at age 18, for which he underwent concurrent chemoradiotherapy. According to his father, he had not eaten food since the night prior but consumed large amounts of alcohol. Upon arrival at the ED, the patient was stuporous, tachypneic at 26 breaths per minute, blood pressure 134/109 mmHg, heart rate 85 beats per minute, and afebrile. Initial blood work showed glucose of 420 mg/dl, high levels of alcohol (222.7 mg/dl), metabolic acidosis (pH 6.6), elevated ketones At the ICU, the patient was intubated due to hypoxemic respiratory failure. He underwent continuous renal replacement therapy owing to acute kidney injury and severe metabolic acidosis. Empiric antibiotics were prescribed because of suspected sepsis (Sequential Organ Failure Assessment Score: 9). His blood culture further con rmed growth of Pseudomonas Aeruginosa and Acinetobacter Baumannii. Antibiotics were adjusted according to susceptibility. Additional blood test revealed negative for HBV, HCV, and HIV antibodies. His condition gradually improved and was successfully extubated on day 10.
However, on day 11 of admission, massive hematochezia of 1500 ml was noted, and his Hb dropped from 9.5 g/dl to 8.2 g/dl. Blood transfusion, vitamin K, and tranexamic acid was immediately administered. GI was consulted for colonoscopy the next day. During the colonoscopy, other than blood clots and stool visualized along the proceeding scope, a deep ulcer covered with mucus with peripheral elevation was noted at the transverse colon (Fig. 1). A biopsy was done and the specimen was sent to pathology. Histopathology of the biopsy revealed nonpigmented, wide (5-20 µm in diameter), thin-walled, ribbon-like hyphae with few septations and right-angle branching suggestive of mucormycosis demonstrated by Periodic acid-Schiff (PAS) stain (Fig. 2). Blood cultures taken at that time were negative of growth and upper endoscopy did not reveal similar lesions.
Upon receiving the pathology report, the patient was started on oral Posaconazole therapy. No hematochezia was observed after starting the treatment and his c-reactive protein levels continued to decline (from 3.2 to 0.16). The patient's condition gradually stabilized and was subsequently stepped down from the ICU to the ward and subsequently discharged two weeks later. He received a total of 2 months of Posaconazole therapy. A follow up colonoscopy was done one month post treatment where no lesions were visualized (Fig. 3).

Discussion
One rare cause of lower GI bleeding is GI mucormycosis. Mucormycosis is an opportunistic infection caused by fungi in the order of Mucorales (5). The low virulence of these organisms makes disease rare among immunocompetent individuals (6). However, prognosis among infected individuals are extremely poor, and mortality has been found to be associated with the site of infection (5). Most infected patients have underlying factors of compromised immunity, such as organ transplantation, malignancy, persistent neutropenia, poorly controlled diabetes mellitus and systemic corticosteroid therapy (7,8).
Mucormycosis can manifest as different clinical syndromes: rhino-orbito-cerebral, pulmonary, cutaneous, gastrointestinal, disseminated, and uncommon presentations. Among these manifestations, gastrointestinal mucormoycosis is the rarest, making up only around 7% of all cases (6). Disease of the gastrointestinal tract is usually acquired through ingestion of contaminated food or device. Within the gastrointestinal tract, the stomach is the most common sight of infection, followed by the colon. Mortality of GI mucormyocosis has been reported to be as high as 85% (9). Patients often present with nonspeci c symptoms such as abdominal pain, GI bleeding, change in bowel habits, and fever (5). It has been reported that the majority of patients presented with abdominal pain in the absence of fever (10). Nonspeci c clinical presentation make diagnosis di cult and often delayed, and therefore contributes to the high mortality rate. It is estimated that less than half of the diagnosis of mucormycosis are made antepartum (8).
De nite diagnosis of mucormycosis is made by histopathological evidence of fungal invasion of tissue.
Unlike aspergillosis, there is no reliable serological test for mucormycosis. In the case of GI mucormycosis, undergoing invasive endoscopy or even surgery is usually inevitable for diagnosis. A dark ulcer with sharp demarcated edges along with necrosis and thrombosis in the adjacent vessels is representative of a typical GI lesion (8). Endoscopic nding of a small, mushroom-like green mass with a small base attached to the colon wall has also been described in previous studies (11). Extended lesions can cause perforation, bleeding, and obstruction.
With the widespread availability of endoscopic techniques, early clinical suspicion and diagnosis as well as effective treatment are critical in reducing mortality. However, many patients with severe acute LGIB are unable to tolerate rapid colon preparation for diagnostic colonoscopy, making localization of lesions challenging due to poor visualization. Therefore, in immunocompromised patients such as those with DKA, organ transplantation, and malignancy, it is important to consider the possibility of GI mucormycosis. In cases with clinical suspicion but timely diagnosis cannot be made, prophylaxis antifungal treatment should not be delayed.
It is advised that treatment of mucormycosis include urgent surgical resection of infected area whenever feasible parallel to systemic antifungal therapy to prevent disease dissemination (7,12). Liposomal amphotericin B is the recommended rst line treatment for mucormycosis. Posaconazole has generally been recommended as maintenance and salvage therapy. However, Song et. al reported a higher survival rate in renal transplant patients with mucormycosis treated with Posaconazole compared to Amphotericin B (13). European Confederation of Medical Mycology 2019 guideline proposes the use of Posaconazole as rst line treatment with moderate strength, especially in case of renal failure like our patient (14). Reversal of underlying problems is also fundamental to improve treatment outcome (7,8). A study by Gebremariam et. al highlighted the importance of correcting acidemia in patients with ketoacidosis (15). For our patient, proper control of his diabetes mellitus and succession of alcohol drinking are of great importance.

Conclusion
Mucormycosis is a life-threatening fungal infection caused by Mucorales, primarily affecting the immunocompromised hosts. A rare clinical presentation of mucormycosis of the GI tract is hematochezia. Early diagnosis and treatment of mucormycosis infection is critical but can be challenging, especially in the setting of massive hematochezia where adequate bowel preparation for diagnostic colonoscopy cannot be achieved. Therefore, colonic opportunistic infections such as mucormycosis should be a differential diagnosis for massive GI bleeding in immunocompromised patients. In cases with high clinical suspicion, prompt prophylaxis is critical.

Consent for publication:
A written consent of personal information for publication was obtained from the patient.
Availability of data and materials: All data generated during this study are included in this published article.

Competing interests:
None declared by the authors.   Nonpigmented, wide (5-20 µm in diameter), thin-walled, ribbon-like hyphae with few septations and rightangle branching suggestive of mucormycosis was demonstrated by PAS stain