Incidence of histoplasmosis following allogeneic bone marrow transplant or solid organ transplant in a hyperendemic area

Abstract

Questions have arisen regarding the risk of developing symptomatic Histoplasma capsulatum infection among patients who undergo transplant-related immunosuppression in areas endemic for histoplasmosis. Our medical center is located in a hyperendemic area for histoplasmosis, where three large outbreaks occurred since 1978. We undertook a retrospective chart review of 137 patients who received allogeneic bone marrow transplant and of 449 patients who received solid organ transplant from January 1994 to December 1996 in order to assess the incidence of active histoplasmosis. Charts were reviewed before and after transplantation for clinical outcomes, H. capsulatum serologies and antigen results, and microbiological and radiological results. After a mean follow-up duration exceeding 16 months, no patient was diagnosed with histoplasmosis. In the absence of an outbreak, histoplasmosis is a rare infection following the immunosuppression of allogeneic bone marrow or solid organ transplantation even in a hyperendemic area. Pre-transplant serologies or chest radiographs consistent with prior infection were not associated with post-transplant histoplasmosis.

Transmission of Tropical and Geographically Restricted Infections during Solid-Organ Transplantation

“…A study performed in Indianapolis, IN, at a medical center located in an area of hyperendemicity demonstrated that histoplasmosis is a rare infection following the immunosuppression of allogeneic bone marrow transplantation (BMT) or SOT (377). In this study, 18% of the recipients had CF titers that were positive for H. capsulatum, and chest X rays showed findings consistent with past histoplasmosis in 4% of the recipients.…”

“…Some authors postulated that most of the posttransplant cases of histoplasmosis in areas of endemicity occur de novo during an outbreak and are not due to reactivation, and consequently, routine prophylactic antifungal therapy for the prevention of histoplasmosis following SOT cannot be recommended for these recipients (377). However, other authors believe itraconazole prophylaxis should be offered to recipients of organs from a seropositive donor.…”

Mycobacterium haemophilum and Histoplasma capsulatum Coinfection in a Renal Transplant Patient

“…However, Peddi et al reported 4 cases of renal transplant recipients that received intense immunosuppressive therapy in the 3 months prior to the onset of the infection (19). There are very low incidences of histoplasmosis among allogeneic-bone-marrowand solid-organ-transplant recipients, even in areas of hyperendemicity, and the risk of reactivation is also very low (23). This infection is very rare in our population.…”

“…However, we were able to identify small mycobacterial colonies 3 days after incubation on chocolate agar plates, probably due to a very heavy inoculum. On microscopic examination, M. haemophilum usually appears as a short, beaded bacillus that may exhibit cording similar to that observed with Mycobacterium tuberculosis (13,19,23). Cord formation, or cording, is considered a virulence factor, first identified in M. tuberculosis.…”

“…It grows optimally at 30°C to 32°C, which may explain the predilection of this organism for infection of cooler areas of the body, such as the extremities, similar to what is observed for Mycobacterium ulcerans and Mycobacterium marinum. Also, for optimal growth, culture medium must be supplemented with iron-containing compounds, such as ferric ammonium citrate of hemin, and the addition of 10% CO 2 to the atmosphere (13,23). In our laboratory, an additional Middlebrook 7H11 biplate and a chocolate agar plate are incubated at 30°C, with addition of 10% CO 2 for mycobacterial isolation from tissues taken from external sites (e.g., skin biopsy specimens, abscesses, or ulcers).…”