Histoplasma capsulatum Endocarditis

Abstract

Infective endocarditis is an uncommon manifestation of infection with Histoplasma capsulatum. The diagnosis is frequently missed, and outcomes historically have been poor. We present 14 cases of Histoplasma endocarditis seen in the last decade at medical centers throughout the United States. All patients were men, and 10 of the 14 had an infected prosthetic aortic valve. One patient had an infected left atrial myxoma. Symptoms were present a median of 7 weeks before the diagnosis was established. Blood cultures yielded H. capsulatum in only 6 (43%) patients. Histoplasma antigen was present in urine and/or serum in all but 3 of the patients and provided the first clue to the diagnosis of histoplasmosis for several patients. Antibody testing was positive for H. capsulatum in 6 of 8 patients in whom the test was performed.Eleven patients underwent surgery for valve replacement or myxoma removal. Large, friable vegetations were noted at surgery in most patients, confirming the preoperative transesophageal echocardiography findings. Histopathologic examination of valve tissue and the myxoma revealed granulomatous inflammation and large numbers of organisms in most specimens. Four of the excised valves and the atrial myxoma showed a mixture of both yeast and hyphal forms on histopathology.A lipid formulation of amphotericin B, administered for a median of 29 days, was the initial therapy in 11 of the 14 patients. This was followed by oral itraconazole therapy, in all but 2 patients. The length of itraconazole suppressive therapy ranged from 11 months to lifelong administration. Three patients (21%) died within 3 months of the date of diagnosis. All 3 deaths were in patients who had received either no or minimal (1 day and 1 week) amphotericin B.

Diagnostic Importance of Hyphae on Heart Valve Tissue in Histoplasma Endocarditis and Treatment With Isavuconazole

“…H. capsulatum is a rare cause of infectious endocarditis, with only 58 previously described cases [3, 4]. In this case, yeast and hyphae were seen in excised cardiac valve tissue before results were available by fungal culture, urine Histoplasma antigen, and serological and molecular testing.…”

“…Expert opinion recommendations include surgical debridement or valve replacement followed by an initial period with amphotericin, then a prolonged or lifelong course of itraconazole [4]. Although an off-label use, isavuconazole may be effective treatment for H. capsulatum endocarditis.…”

A case report of Histoplasma capsulatum prosthetic valve endocarditis: an extremely rare presentation with characteristic findings

“…Other clinical signs associated with histoplasmosis include skin lesions, lymphadenopathy, pulmonary nodules, hepatosplenomegaly, pallor, petechiae, and embolic phenomenon 3 . Histoplasma capsulatum infection is endemic in certain areas of North, Central, and South America, Africa, and Asia.…”

“…In contrast, Histoplasma capsulatum is an extremely rare cause of PVE and can present with non-specific symptoms 2 . These factors, coupled with negative or delayed positive blood cultures (including both ‘routine' and ‘fungal' cultures), are responsible for delayed diagnosis (median, 7 weeks) in most cases 3 . A 40-year institutional experience of fungal PVE at Mayo Clinic included only 3 (14%) of 21 cases due to H. capsulatum.…”

Severe pulmonic valve regurgitation due to histoplasma endocarditis

“…The largest series on H. capsulatum IE encompasses 43 cases published between 1943 and 2003 (5) . Fourteen more cases of H. capsulatum IE were reported during 2003–2012, at medical centers throughout the USA (6) . To the best of our knowledge, isolated Histoplasma endocarditis of pulmonic valve has not been previously reported.…”