Histoplasma capsulatum prosthetic valve endocarditis with negative fungal blood cultures and negative histoplasma antigen assay in an immunocompetent patient

HISTOPLASMA CAPSULATUM PACEMAKER-RELATED ENDOCARDITIS PRESENTING AS ENDOGENOUS ENDOPHTHALMITIS

BACKGROUND/PURPOSE

To report a unique case of pacemaker-related infective endocarditis manifesting as endogenous endophthalmitis with chorioretinitis secondary to Histoplasma capsulatum.

METHODS

Case report.

RESULTS

A 75-year-old man was diagnosed with blood culture-negative infective endocarditis and was admitted with deteriorating vision and ocular inflammation. Examination of the eye indicated significant vitreous inflammation and retinitis. Vitreous cultures were negative, but universal fungal polymerase chain reaction of the vitreous fluid was positive for H. capsulatum. Histopathology of the fibrous cuff around the extracted right atrial lead demonstrated hyphal and yeast forms and polymerase chain reaction of this material identified H. capsulatum. Despite aggressive antifungal and surgical treatment, the eye became phthisical.

CONCLUSION

We highlight the importance of considering H. capsulatum in the differential diagnosis of endogenous endophthalmitis, particularly among patients from endemic areas who present with possible endovascular infection.

Rare case of Histoplasma capsulatum endocarditis in a patient with a prosthetic valve

BACKGROUND

Diagnosis of fungal endocarditis can be challenging, especially among cases with negative blood culture results. Of fungal endocarditis cases, Histoplasma capsulatum constitutes an even smaller proportion with ∼58 prior cases reported. Due to the rarity of histoplasmosis endocarditis and thus limited data, there is no current diagnostic guideline for testing within culture negative infective endocarditis.

CASE SUMMARY

Our patient was a 58-year-old female presenting with worsening dyspnoea, hypotension, and near-syncope. In this case report, we depict the clinical presentation and diagnosis of H. capsulatum endocarditis in a female patient with a prosthetic aortic valve and negative blood cultures. We further demonstrate the rising risk of fungal endocarditis with use of external devices.

DISCUSSION

Despite the rarity of fungal endocarditis, there has been a recent upward trend in infections given the rising use of external devices, greater number of immunocompromised patients, and rising rates of intravenous drug use. Recently, more cases of fungal endocarditis have been occurring in patients with prosthetic valves compared to native. Although H. capsulatum constitutes a smaller proportion of fungal endocarditis cases, patients with appropriate risk factors and those who have been exposed to at-risk areas such as the Ohio and Mississippi River valleys, may benefit from further evaluation.

Native vs Prosthetic Valve Histoplasma capsulatum Infective Endocarditis: A Case Report and Systemic Literature Review Comparing Patient Presentation, Treatment Modalities, Clinical Outcomes, and Diagnostic Laboratory Testing

Histoplasma capsulatum is a rare cause of fungal endocarditis that affects both native and prosthetic valves. It is associated with a high mortality rate if not diagnosed early and treated with a combination of antifungal therapy and surgical intervention. We present a case of a 47-year-old man with histoplasmosis infective endocarditis. He was successfully treated with antifungal therapy and surgical replacement of the infected bioprosthetic aortic valve. Our systemic literature review includes 52 articles encompassing 60 individual cases of H. capsulatum infective endocarditis from 1940 to 2020. Patient presentations, diagnostic laboratory testing accuracy, treatment modalities, and patient outcomes comparing and contrasting native and prosthetic valve infection are described.

Could Histoplasma capsulatum Be Related to Healthcare-Associated Infections?

Healthcare-associated infections (HAI) are described in diverse settings. The main etiologic agents of HAI are bacteria (85%) and fungi (13%). Some factors increase the risk for HAI, particularly the use of medical devices; patients with severe cuts, wounds, and burns; stays in the intensive care unit, surgery, and hospital reconstruction works. Several fungal HAI are caused by Candida spp., usually from an endogenous source; however, cross-transmission via the hands of healthcare workers or contaminated devices can occur. Although other medically important fungi, such as Blastomyces dermatitidis, Paracoccidioides brasiliensis, and Histoplasma capsulatum, have never been considered nosocomial pathogens, there are some factors that point out the pros and cons for this possibility. Among these fungi, H. capsulatum infection has been linked to different medical devices and surgery implants. The filamentous form of H. capsulatum may be present in hospital settings, as this fungus adapts to different types of climates and has great dispersion ability. Although conventional pathogen identification techniques have never identified H. capsulatum in the hospital environment, molecular biology procedures could be useful in this setting. More research on H. capsulatum as a HAI etiologic agent is needed, since it causes a severe and often fatal disease in immunocompromised patients.

Histoplasma capsulatum endocarditis: multicenter case series with review of current diagnostic techniques and treatment

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.

Fatal Histoplasma capsulatum mitral endocarditis in a French patient treated for rheumatoid arthritis

Histoplasmosis is an infectious disease caused by the inhalation of Histoplasma capsulatum spores, a fungus encountered in many diverse areas around the world. Although this infection is often asymptomatic, it may become dramatic in immunocompromised patients. In November 2005, an endocarditis due to Histoplasma capsulatum was diagnosed in a French woman treated for rheumatoid arthritis and who had traveled to South America 2 years earlier. We confirmed the biological diagnosis by mycological, serological, and histological methods. In spite of receiving the appropriate treatment, the patient died 3 months later of cardiac insufficiency. We report here this additional case of Histoplasma endocarditis, by hoping to help rapid and accurate diagnosis of such infections in their early stages of development, in non-endemic areas.