A Case of Disseminated Histoplasmosis in Transplant Patient

Introduction: Histoplasma(HP) capsulatum is a dimorphic fungus with a worldwide distribution. In a study from a hyperendemic area, 24% of the solid organ transplant(SOT) candidates had evidence of prior exposure to HP. In immunocompetent patients, HC is usually mild, but in immunocompromised patients like SOT recipients it develops into severe infection with dissemination to extrapulmonary organs. We present a case of disseminated histoplasmosis in a kidney transplant recipient Case Description: 35 y.o. M with HTN, recurrent UTI, failed LDKT from 2006 and DDKT in 2022, presented for fever, melena, and diarrhea for a day with exposure to farm animals in a recent trip to Trinidad. Vital signs, system review and PE were otherwise unremarkable. Labs showed BUN/Creat of 78/3.2, from baseline of 2.6, HGB 6.2, K 6.6. He was transfused with 4u of PRBCs, and hyperkalemia was treated medically. Endo-Colonoscopy was delayed due to history of fever. He was on Tac 3mg BID and MMF 1gm BID. The patient was empirically started on treatment for C-Diff and UTI, blood and urine cultures were negative. Respiratory panel detected Rhinovirus/Enterovirus. CT abdomen and pelvis showed bilateral pulmonary nodules and multiple enlarged retroperitoneal and mesenteric lymph nodes. BAL was positive for fungal infection (FI). HP Urine Ag was positive (6.4 ng/mL). He improved significantly on Voriconazole and was switched to Itraconazole to cover broadly for 1 year. He became afebrile after 48 hours of antifungal treatment. Tacrolimus was reduced to 1mg bid, level on the day of discharge 9.3 Discussion: HP accounts for <5% of all invasive FI in SOT recipients, the infections can be devastating. Transplant-associated HP can occur as a de-novo infection from an environmental exposure which was most likely in our patient, or as the reactivation of a latent infection or donor-derived (DD) transmission. DD HP is seen in 1:10,000 transplants and occurs in the early post-transplant period. The agent of choice and duration of therapy depends on the severity of disease but all SOT with HP require therapy. Our patient initially came with a GI complaint and the disseminated infection was discovered incidentally. With rising incidence of FI due to climate change, clinicians must have a high index of suspicion in all difficult to diagnose infections among SOT recipients especially in those who visited endemic area's