In Search for Equilibrium: Immunosuppression Versus Opportunistic Infection

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.

Antibiotics-mediated intestinal microbiome perturbation aggravates tacrolimus-induced glucose disorders in mice

Both immunosuppressants and antibiotics (ABX) are indispensable for transplant patients. However, the former increases the risk of new-onset diabetes, whereas the latter impacts intestinal microbiota (IM). It is still unclear whether and how the interaction between immunosuppressants and ABX alters the IM and thus leads to glucose metabolism disorders. This study examined the alterations of glucose and lipid metabolism and IM in mice exposed to tacrolimus (TAC) with or without ABX. We found that ABX further aggravated TAC-induced glucose tolerance and increased insulin secretion. Combined treatment resulted in exacerbated lipid accumulation in the liver. TAC-altered microbial community was further amplified by ABX administration, as characterized by reductions in phylum Firmicutes, family Lachnospiraceae, and genus Coprococcus. Analyses based on the metagenomic profiles revealed that ABX augmented the effect of TAC on microbial metabolic function mostly related to lipid metabolism. The altered components of gut microbiome and predicted microbial functional profiles showed significant correlation with hepatic lipid accumulation and glucose disorders. In conclusion, ABX aggravated the effect of TAC on the microbiome and its metabolic capacities, which might contribute to hepatic lipid accumulation and glucose disorders. These findings suggest that the ABX-altered microbiome can amplify the diabetogenic effect of TAC and could be a novel therapeutic target for patients.