Histoplasma endocarditis on a stenosed aortic valve presenting as dysphagia and weight loss

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.

Endovascular infections caused by Histoplasma capsulatum: a case series and review of the literature

CONTEXT

Endovascular infection is an uncommon but devastating manifestation of histoplasmosis, which is often diagnosed late in disease.

OBJECTIVES

To evaluate the clinical and pathologic characteristics of patients with endovascular infections caused by Histoplasma capsulatum.

DESIGN

All cases of patients with documented endovascular histoplasmosis at a single tertiary care center in an endemic region during the period 1993-2010 were reviewed.

RESULTS

Patients presented with a subacute febrile illness and a history of endovascular devices. All patients had positive Histoplasma serology. Routine bacterial culture results were negative for all patients. In addition to yeast forms typical of histoplasmosis, pathologic findings also revealed mycelial forms in 4 of 5 patients. Inflammation was scant. Urinary antigen detection was positive in 4 of 5 patients and Histoplasma blood culture results were positive for 3 of 5 patients. Four patients were treated with a combination of surgical and medical therapy, which consisted of amphotericin B followed by itraconazole; these 4 patients had complete resolution of symptoms and no documented relapse. One patient died before planned surgery.

CONCLUSIONS

Histoplasma capsulatum endovascular infections are clinically characterized by a subacute febrile illness with negative bacterial cultures in patients with prosthetic endografts or valves. Noninvasive diagnostics are often the initial clue to the diagnosis. Combined medical and surgical treatment is associated with survival. On histopathologic examination both mycelial and yeast forms are often observed, with absent to minimal tissue inflammatory reaction.

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

We report a case of Histoplasma capsulatum endocarditis in which Histoplasma antigen assay and fungal blood cultures were negative. The diagnosis was made by microscopic examination and culture of the excised valve. Histoplasma capsulatum should be considered in the differential diagnosis of culture-negative endocarditis in regions where it is endemic and in travelers.

Dysphagia as an unusual presentation of infective endocarditis

We report a case of a 79-y-old male with enterococcal endocarditis presenting with dysphagia and weight loss. The patient's longstanding underlying bacteremia was thought to have caused pro-inflammatory changes leading to alterations in the neuronal environment affecting peripheral nerve function. Dysphagia improved once antibiotic treatment was initiated.

Histoplasma endocarditis: clinical and mycologic features and outcomes

OBJECTIVES

To define the salient clinical and microbiologic characteristics and outcome of infective endocarditis caused by Histoplasma capsulatum.

METHODS

Case report and review of 43 literature cases.

RESULTS

Infection involved both native (36 cases) and prosthetic (7) heart valves, had a high rate of systemic embolization (58%), and a more delayed diagnosis than bacterial endocarditis. Cardiac involvement generally occurred on mitral and/or aortic valves, and almost always in the setting of disseminated disease. Antemortem diagnosis was best made by serology (serum antibody titers or urinary antigen) or culture of blood (positive in <20% of cases), bone marrow, excised valves, and other non-blood specimens. Other diagnostic methods included histopathology and immunofluorescent staining of tissue samples. Untreated infection was uniformly fatal. Prolonged antifungal therapy with amphotericin B, without surgical intervention, appeared more effective than for Candida endocarditis.

CONCLUSIONS

Histoplasma endocarditis is an infrequent but important cause of left-sided, blood culture-negative endocarditis. Its true prevalence may be underestimated because of the relative difficulty in making a precise microbiologic diagnosis. Amphotericin B therapy appears more effective than for Candida endocarditis, while the role for azole treatment and secondary prophylaxis remains uncertain. Indications for surgical valve replacement are similar to those for bacterial endocarditis.

Blood culture negative endocarditis: analysis of 63 cases presenting over 25 years

OBJECTIVE

To analyse cases of blood culture negative endocarditis (BCNE) seen at St Thomas' Hospital, London, between 1975 and 2000.

METHODS

Data on all episodes of endocarditis with negative blood cultures seen at St Thomas' Hospital between 1975 and 2000 were collected prospectively and analysed retrospectively.

RESULTS

Sixty three patients with BCNE were seen during the study period: 48 (76%) with native and 15 (24%) prosthetic valve infection. BCNE accounted for 12.2% of the 516 cases of endocarditis seen at St Thomas' Hospital. The diagnosis of endocarditis was clinically definite by the Duke criteria in only 21% (7 of 34) of cases of pathologically proven native valve endocarditis but in 62% (21 of 34) of cases by the St Thomas' modifications of the criteria. Comparable figures for the 11 cases of pathologically proven prosthetic valve endocarditis were 45% and 73%. Despite negative blood cultures a causative organism was identified in 31 (49%) of the 63 cases: in 15 by serology (8 Coxiella burnetii, 6 Bartonella species, and 1 Chlamydia psittaci); in 9 cases by culture of the excised valve; in 3 by microscopy of the excised valve, on which large numbers of Gram positive cocci were seen although the culture was sterile; and in the other 4 by isolation from a site other than the excised valve (2 respiratory specimens, 1 from the pacemaker tip, and 1 from an excised embolus). In addition 5 of the 6 cases of Bartonella infection were confirmed by polymerase chain reaction study of the excised valve. Two thirds of the 32 patients for whom no pathogen was identified had received antibiotics before blood was cultured. Thus truly "negative" endocarditis was very uncommon (6% of the cases).

CONCLUSION

If blood cultures are negative in definite or suspected endocarditis, serum should be analysed for Bartonella, Coxiella, and Chlamydia species antibodies, and the excised valve or (rarely) embolus should be analysed by microscopy, culture, histology, and relevant polymerase chain reaction. Other specimens may be relevant. The Duke criteria performed poorly in BCNE; St Thomas' additional minor criteria gave more definite diagnoses.

Acute disseminated histoplasmosis and endocarditis

Acute disseminated histoplasmosis is a frequent condition in HIV carriers. Thirty-five cases of endocarditis caused by Histoplasma capsulatum have been reported in international literature, and all these descriptions correspond to a context of subacute disseminated histoplasmosis. This paper presents the case of a HIV-positive patient with fever, dyspnea, weight loss, vomiting and polyadenopathies to whom histoplasmosis was diagnosed following blood-cultures and isolation of the agent responsible for cutaneous lesions, and in whom aortic-valve vegetations were found during an echocardiogram. The patient was treated with amphotericin B and had a good outcome; subsequent echocardiograms showed no vegetations. Literature on the subject is reviewed, with special emphasis on diagnosis and treatment of previously described cases.