High histoplasmosis incidence in kidney transplant recipients in Santa Fe city, Argentina.

Histoplasmosis is endemic in the central/northeast region of Argentina. It is estimated that the incidence of this mycosis is low in solid organ transplant recipients. This work aims to describe the epidemiology, clinical forms, and evolution of kidney transplant recipients diagnosed with histoplasmosis in Santa Fe city, Argentina. A retrospective study was carried out between 2015 and 2020 on kidney transplant patients with symptoms associated with histoplasmosis in Santa Fe. Histoplasmosis diagnosis was performed through histopathology, recovery of Histoplasma spp., by culture, and/or positive nested Polimerase Chain Reaction (PCR) specific for the Histoplasma Hc100 gene. During the study period, 360 kidney transplantations were performed. Of these patients, 12 were diagnosed with histoplasmosis (3.3%). The patients' median age was 51 years, and 75% were male. Eleven patients (92%) presented the disseminated form of the disease. Thirty-three percent were diagnosed with histoplasmosis in their first year post-transplantation (mostly 6-12 months), while 42% received their diagnosis 3 years after transplantation. Laboratory diagnosis was performed by histopathology, culture, and PCR in four cases (33%), by culture and PCR in three cases (25%), and by PCR alone in three cases (25%). Thus, all 12 patients showed positive nested PCR results. All patients received amphotericin B as initial treatment. A good response was observed in 83% of patients. We found a high incidence of histoplasmosis in kidney transplant recipients (up to 10 times higher than reports from other endemic areas). Diagnosis by histopathology/culture showed 75% sensitivity, while nested PCR showed better sensitivity and diagnostic speed.