Disseminated cryptococcosis in Crohn's disease: a case report

The Intricate Connection between Bacterial α-Diversity and Fungal Engraftment in the Human Gut of Healthy and Impaired Individuals as Studied Using the In Vitro SHIME® Model

From the estimated 2.2 to 3.8 million fungal species existing on Earth, only a minor fraction actively colonizes the human gastrointestinal tract. In fact, these fungi only represent 0.1% of the gastrointestinal biosphere. Despite their low abundance, fungi play dual roles in human health-both beneficial and detrimental. Fungal infections are often associated with bacterial dysbiosis following antibiotic use, yet our understanding of gut fungi-bacteria interactions remains limited. Here, we used the SHIME® gut model to explore the colonization of human fecal-derived fungi across gastrointestinal compartments. We accounted for the high inter-individual microbial diversity by using fecal samples from healthy adults, healthy babies, and Crohn's disease patients. Using quantitative Polymerase Chain Reaction and targeted next-generation sequencing, we demonstrated that SHIME®-colonized mycobiomes change upon loss of transient colonizers. In addition, SHIME® reactors from Crohn's disease patients contained comparable bacterial levels as healthy adults but higher fungal concentrations, indicating unpredictable correlations between fungal levels and total bacterial counts. Our findings rather link higher bacterial α-diversity to limited fungal growth, tied to colonization resistance. Hence, while healthy individuals had fewer fungi engrafting the colonic reactors, low α-diversity in impaired (Crohn's disease patients) or immature (babies) microbiota was associated with greater fungal abundance. To validate, antibiotic-treated healthy colonic microbiomes demonstrated increased fungal colonization susceptibility, and bacterial taxa that were negatively correlated with fungal expansion were identified. In summary, fungal colonization varied individually and transiently, and bacterial resistance to fungal overgrowth was more related with specific bacterial genera than total bacterial load. This study sheds light on fungal-bacterial dynamics in the human gut.

Disseminated cryptococcosis with gastrointestinal involvement and false-negative cryptococcal antigen testing due to postzone phenomenon: a case report and review of the literature

BACKGROUND

Cryptococcosis is an increasingly common infection given the growing immunocompromised population worldwide. Cryptococcal antigen (CrAg) testing demonstrates excellent sensitivity and specificity and is the mainstay of diagnosis. However, there may be rare instances in which false-negative CrAg results can delay diagnosis and early treatment, which are critical to ensure positive outcomes.

CASE PRESENTATION

A 31-year-old man living with HIV/AIDS who was not taking antiretroviral therapy was hospitalized with fever, diarrhea, and headaches. CD4 count on presentation was 71 cells/uL, and HIV viral load was 3,194,949 copies/mL. Serum CrAg testing was initially negative, however CSF CrAg performed several days later was positive at 1:40 and blood and CSF cultures grew Cryptococcus neoformans. Colonoscopy revealed mucosal papules throughout the sigmoid colon, and tissue biopsy showed yeast within the lamina propria consistent with GI cryptococcosis. Given the high burden of disease, the original serum CrAg specimen was serially diluted and subsequently found to be positive at 1:2,560, confirming the postzone phenomenon.

CONCLUSION

Cryptococcosis has a wide array of presentations including intraluminal GI disease, as seen in this patient. While serum CrAg testing displays excellent test characteristics, it is important for clinicians to be aware of the rare instances in which false-negative results may occur in the presence of excess antigen, as in this case.

Pulmonary cryptococcosis after immunomodulator treatment in patients with Crohn’s disease: Three case reports

BACKGROUND

Corticosteroids and anti-tumor necrosis factor α mAbs are widely used to treat Crohn's disease (CD). However, one disadvantage of this treatment is impairment of normal immune function, leading to an increased risk of infection. Cryptococcus infection is an opportunistic infection that occurs mainly in immunocompromised patients and poses a significant diagnostic challenge in patients with CD.

CASE SUMMARY

Here, we report three cases of pulmonary cryptococcosis in patients with CD after receiving immunomodulatory treatment. The patients presented with no or mild respiratory symptoms. Chest computed tomography scans revealed pulmonary nodules in the unilateral or bilateral lobes. Diagnoses were made using pathological examination and metagenomic sequencing. The patients were treated with fluconazole 400 mg once daily for 1 to 6 mo, and symptoms were resolved. Literature searches were conducted in PubMed, Web of Science, and Embase to retrieve previously reported cases and summarize patient characteristics.

CONCLUSION

The incidence of cryptococcus infection has increased along with immunomodulator use. Clinical vigilance is required for early identification and standardized treatment.

Gastrointestinal histoplasmosis complicating pediatric Crohn disease: A case report and review of literature

BACKGROUND

Infection with Histoplasma capsulatum (H. capsulatum) can lead to disseminated disease involving the gastrointestinal tract presenting as diffuse abdominal pain and diarrhea which may mimic inflammatory bowel disease (IBD).

CASE SUMMARY

We report a case of 12-year-old boy with presumptive diagnosis of Crohn disease (CD) that presented with several months of abdominal pain, weight loss and bloody diarrhea. Colonoscopy showed patchy moderate inflammation characterized by erythema and numerous pseudopolyps involving the terminal ileum, cecum, and ascending colon. Histologic sections from the colon biopsy revealed diffuse cellular infiltrate within the lamina propria with scattered histiocytic aggregates, and occasional non-necrotizing granulomas. Grocott-Gomori’s Methenamine Silver staining confirmed the presence of numerous yeast forms suggestive of Histoplasma spp., further confirmed with positive urine Histoplasma antigen (6.58 ng/mL, range 0.2-20 ng/mL) and serum immunoglobulin G antibodies to Histoplasma (35.9 EU, range 10.0-80.0 EU). Intravenous amphotericin was administered then transitioned to oral itraconazole. Follow-up computed tomography imaging showed a left lower lung nodule and mesenteric lymphadenopathy consistent with disseminated histoplasmosis infection.

CONCLUSION

Gastrointestinal involvement with H. capsulatum with no accompanying respiratory symptoms is exceedingly rare and recognition is often delayed due to the overlapping clinical manifestations of IBD. This case illustrates the importance of excluding infectious etiologies in patients with “biopsy-proven” CD prior to initiating immunosuppressive therapies. Communication between clinicians and pathologists is crucial as blood cultures and antigen testing are key studies that should be performed in all suspected cases of histoplasmosis to avoid misdiagnosis and inappropriate treatment.

Disseminated Cryptococcal Infection in HIV-Infected Patients: A Retrospective Clinicopathological Review of 4 Autopsy Cases

Cryptococcosis is an opportunistic infection with high mortality if not diagnosed and treated in time. The objective of this study was to review the clinicopathological information of decendents with final autopsy diagnosis of disseminated cryptococcal infection. This study collected data from 4 decendents who presented to an academic hospital/laboratory between 1 January 2015 to 31 December 2018. Their clinical, radiological and pathological findings including treatment were reviewed. Two decendents presented with respiratory symptoms whilst the other 2 presented with meningeal symptoms. Three were confirmed HIV positive. One decendent was on ART, one had defaulted treatment and one was ART naïve. Two decendents were diagnosed with cryptococcal meningitis, one with bacterial pneumonia and one with pulmonary tuberculosis. Three decendents died in emergency unit and one in the ward whilst on antifungal therapy. The autopsy findings confirmed disseminated cryptococcal infection in all cases. A high index of suspicion should be maintained in the right clinical context. Multi-organ involvement should be suspected in all patients and be actively sought out.

Gastrointestinal Histoplasmosis Mimicking Crohn's Disease

Disseminated histoplasmosis is a life-threatening disease usually seen in immunocompromised patients living in endemic areas. We present an apparently immunocompetent patient with gastrointestinal histoplasmosis who was initially diagnosed with biopsy-proven Crohn's disease. Following discontinuation of anti-inflammatory drugs and institution of antifungal therapy, his gastrointestinal illness completely improved. Specific fungal staining should be routinely included in histopathologic assessment of tissue specimens diagnosed as Crohn's disease.

Gastrointestinal Cryptococcosis Associated with Intestinal Lymphangiectasia

Intestinal lymphangiectasia is a pathological dilation of enteric lymphatic vessels resulting in lymph leakage to the intestinal lumen. This chronic lymph leakage leads to a state of immunosuppression secondary to the loss of humoral and cellular components of the immune system and represents a potential risk factor for opportunistic infections. We report a case of protein-losing enteropathy in a seemingly immunocompetent patient. An intestinal histopathological study revealed the unusual association of lymphangiectasia and intestinal cryptococcosis. Although cryptococcal infection is common in immunocompromised patients, intestinal involvement is rarely reported. We found no reports on the association of intestinal cryptococcosis in patients with lymphangiectasia. This case report is the first to describe intestinal cryptococcosis associated with intestinal lymphangiectasia.

Serious and Opportunistic Infections in Elderly Patients With Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is often treated with biologics and immunomodulators, which can place elderly IBD patients at risk for serious and opportunistic infections. This article provides an updated account of research on therapies in IBD that are associated with an increased infection risk. Relevant serious and opportunistic infections in the elderly population are discussed along with methods for prevention and treatment. The incidence of infection increases with age and the degree of immunosuppression. Emphasis should be placed on performing vaccinations at the time of IBD diagnosis. Additionally, patients receiving immunosuppressive therapy should avoid live vaccines. Physicians should have a greater awareness of the increased risk of infection in elderly adults and the need for screening for infection prior to initiation of immunosuppressive IBD therapies.