Colonic Infection by Histoplasma capsulatum in a Liver Transplant Patient: A Case Report

Clinical Characteristics and Outcomes of Endemic Mycoses After Solid Organ Transplantation: A Comprehensive Review

Background

Geographically endemic fungi can cause significant disease among solid organ transplant (SOT) recipients. We provide an update on the epidemiology, clinical presentation, and outcomes of 5 endemic mycoses in SOT recipients.

Methods

Multiple databases were reviewed from inception through May 2023 using key words for endemic fungi (eg, coccidioidomycosis or Coccidioides, histoplasmosis or Histoplasma, etc). We included adult SOT recipients and publications in English or with English translation.

Results

Among 16 cohort studies that reported on blastomycosis (n = 3), coccidioidomycosis (n = 5), histoplasmosis (n = 4), and various endemic mycoses (n = 4), the incidence rates varied, as follows: coccidioidomycosis, 1.2%-5.8%; blastomycosis, 0.14%-0.99%; and histoplasmosis, 0.4%-1.1%. There were 204 reports describing 268 unique cases of endemic mycoses, including 172 histoplasmosis, 31 blastomycosis, 34 coccidioidomycosis, 6 paracoccidioidomycosis, and 25 talaromycosis cases. The majority of patients were male (176 of 261 [67.4%]). Transplanted allografts were mostly kidney (192 of 268 [71.6%]), followed by liver (n = 39 [14.6%]), heart (n = 18 [6.7%]), lung (n = 13 [4.9%]), and combined kidney-liver and kidney-pancreas (n = 6 [2.7%]). In all 5 endemic mycoses, most patients presented with fever (162 of 232 [69.8%]) and disseminated disease (179 of 268 [66.8%]). Cytopenias were frequently reported for histoplasmosis (71 of 91 [78.0%]), coccidioidomycosis (8 of 11 [72.7%]) and talaromycosis (7 of 8 [87.5%]). Graft loss was reported in 12 of 136 patients (8.8%). Death from all-causes was reported in 71 of 267 (26.6%); half of the deaths (n = 34 [50%]) were related to the underlying mycoses.

Conclusions

Endemic mycoses commonly present with fever, cytopenias and disseminated disease in SOT recipients. There is a relatively high all-cause mortality rate, including many deaths that were attributed to endemic mycoses.

Gastrointestinal Histoplasmosis: A Descriptive Review, 2001-2021

Gastrointestinal histoplasmosis (GIH) is infrequently described in people without underlying HIV infection. We aimed to compare the clinical presentation of GIH in people with and without HIV infection. We conducted a literature search of published cases of GIH from 2001-2021 and found 212 cases. Of these, 142 (67.0%) were male, and 124 (58.5%) had HIV infection. Most cases were from North America (n = 88, 41.5%) and South America (n = 79, 37.3%). Of the 212 cases, 123 (58.0%) were included in both clinical and pathological analyses. The remainder were excluded as details about clinical and pathological findings were not available. Of the 123 cases, 41 had HIV infection while 82 were without HIV infection. The diagnosis was predominantly by histopathology (n = 109, 88.6%). A significant proportion of people with HIV infection had abdominal pain as the most predominant symptom of GIH compared to those without HIV infection (65.9% versus 41.9%, p < 0.05). The colon was the most affected site with a slightly higher proportion in those with HIV infection compared with cases without HIV infection (46.3% versus 42.7%). The commonest pathologic findings were caecal and ileal ulcers. Caecal ulcers were significantly more frequent in cases with HIV infection compared to those without HIV (32.1% versus 7.1%, p < 0.05). Despite being more common in people with HIV infection, GIH also affects people without HIV infection with similar clinical presentations.

Isolated Colonic Histoplasmosis in Patients Undergoing Immunomodulator Therapy: A Systematic Review

Gastrointestinal histoplasmosis remains an inconspicuous clinicopathologic entity. It is predominantly considered a protean manifestation of disseminated disease. We hereby delineate a unique case of biopsy-proven isolated colonic histoplasmosis in a patient undergoing methotrexate therapy. Furthermore, we present the first systematic review of the MEDLINE, Google Scholar, Embase, and Scopus databases regarding isolated colonic histoplasmosis in adult patients receiving immunomodulator therapy (IMT). A total of 13 case reports (level of clinical evidence: IV) were identified. The mean age was 55.6 ± 11.1 years, with 9 (69.2%) cases reported in women. Patients with subclinical disease (5, 38.5%) were often incidentally diagnosed by screening colonoscopy. Symptomatic individuals predominantly presented with diarrhea (4, 30.8%), weight loss (3, 23.1%), and/or abdominal pain (3, 23.1%). IMT was mainly administered for liver transplant (4, 30.8%), renal transplant (4, 30.8%), and ulcerative colitis (2, 15.4%). Common colonoscopy features included colonic ulcerations (7, 53.8%), polyps or pseudopolyps (3, 23.1%), and/or mass-like lesions (3, 23.1%). Diagnosis was made by histology of colonic biopsy in 11 (84.6%) and resected specimens in 2 (15.4%) patients. Treatment consisted of a combination of amphotericin B with oral itraconazole in 6 (46.2%), oral itraconazole alone in 5 (38.5%), and amphotericin B alone in 2 (15.4%) patients. Complete clinical recovery was achieved in all patients. This article illustrates that isolated colonic involvement can be the only clinical presentation of histoplasmosis. It may masquerade as other bowel disorders, presenting diagnostic and therapeutic conundrums. Gastroenterologists should rule out colonic histoplasmosis in IMT recipients who develop unexplained colitis symptoms.

Opportunist Coinfections by Nontuberculous Mycobacteria and Fungi in Immunocompromised Patients

Nontuberculous mycobacteria (NTM) and many fungal species (spp.) are commonly associated with opportunistic infections (OPIs) in immunocompromised individuals. Moreover, occurrence of concomitant infection by NTM (mainly spp. of Mycobacterium avium complex and Mycobacterium abscessus complex) and fungal spp. (mainly, Aspergillus fumigatus, Histoplasma capsulatum and Cryptococcus neoformans) is very challenging and is associated with poor patient prognosis. The most frequent clinical symptoms for coinfection and infection by single agents (fungi or NTM) are similar. For this reason, the accurate identification of the aetiological agent(s) is crucial to select the best treatment approach. Despite the significance of this topic it has not been sufficiently addressed in the literature. This review aims at summarizing case reports and studies on NTM and fungi coinfection during the last 20 years. In addition, it briefly characterizes OPIs and coinfection, describes key features of opportunistic pathogens (e.g., NTM and fungi) and human host predisposing conditions to OPIs onset and outcome. The review could interest a wide spectrum of audiences, including medical doctors and scientists, to improve awareness of these infections, leading to early identification in clinical settings and increasing research in the field. Improved diagnosis and availability of therapeutic options might contribute to improve the prognosis of patients' survival.