Fungal Endocarditis: An Autopsy Study

Fungal Endocarditis: Pathophysiology, Epidemiology, Clinical Presentation, Diagnosis, and Management

Fungal endocarditis accounts for 1% to 3% of all infective endocarditis cases, is associated with high morbidity and mortality (>70%), and presents numerous challenges during clinical care. Candida spp. are the most common causes of fungal endocarditis, implicated in over 50% of cases, followed by Aspergillus and Histoplasma spp. Important risk factors for fungal endocarditis include prosthetic valves, prior heart surgery, and injection drug use. The signs and symptoms of fungal endocarditis are nonspecific, and a high degree of clinical suspicion coupled with the judicious use of diagnostic tests is required for diagnosis. In addition to microbiological diagnostics (e.g., blood culture for Candida spp. or galactomannan testing and PCR for Aspergillus spp.), echocardiography remains critical for evaluation of potential infective endocarditis, although radionuclide imaging modalities such as 18F-fluorodeoxyglucose positron emission tomography/computed tomography are increasingly being used. A multimodal treatment approach is necessary: surgery is usually required and should be accompanied by long-term systemic antifungal therapy, such as echinocandin therapy for Candida endocarditis or voriconazole therapy for Aspergillus endocarditis.

Fungal infections of the central nervous system

The epidemiology of invasive fungal infections in immunocompromised patients is rapidly changing. Several of the fungi have worldwide distribution. However, some have specific geographical distribution. Sinocranial aspergillosis, mostly described from countries with temperate climates, occurs mostly in otherwise immunocompetent individuals Most of the systemic fungal pathogens have been associated with central nervous system (CNS) involvement. The major advances in CNS fungal infections are in the pathobiology, new diagnostic tools, and new therapies. In spite of these developments, there is still considerable delay in the diagnosis of CNS fungal infection. CNS fungal infections are associated with considerable morbidity and mortality. To achieve good outcomes early diagnosis and early institution of appropriate therapies are the key issues.

Invasive aspergillosis in developing countries

To review invasive aspergillosis (IA) in developing countries, we included those countries, which are mentioned in the document of the International Monetary Fund (IMF), called the Emerging and Developing Economies List, 2009. A PubMed/Medline literature search was performed for studies concerning IA reported during 1970 through March 2010 from these countries. IA is an important cause of morbidity and mortality of hospitalized patients of developing countries, though the exact frequency of the disease is not known due to inadequate reporting and facilities to diagnose. Only a handful of centers from India, China, Thailand, Pakistan, Bangladesh, Sri Lanka, Malaysia, Iran, Iraq, Saudi Arabia, Egypt, Sudan, South Africa, Turkey, Hungary, Brazil, Chile, Colombia, and Argentina had reported case series of IA. As sub-optimum hospital care practice, hospital renovation work in the vicinity of immunocompromised patients, overuse or misuse of steroids and broad-spectrum antibiotics, use of contaminated infusion sets/fluid, and increase in intravenous drug abusers have been reported from those countries, it is expected to find a high rate of IA among patients with high risk, though hard data is missing in most situations. Besides classical risk factors for IA, liver failure, chronic obstructive pulmonary disease, diabetes, and tuberculosis are the newly recognized underlying diseases associated with IA. In Asia, Africa and Middle East sino-orbital or cerebral aspergillosis, and Aspergillus endophthalmitis are emerging diseases and Aspergillus flavus is the predominant species isolated from these infections. The high frequency of A. flavus isolation from these patients may be due to higher prevalence of the fungus in the environment. Cerebral aspergillosis cases are largely due to an extension of the lesion from invasive Aspergillus sinusitis. The majority of the centers rely on conventional techniques including direct microscopy, histopathology, and culture to diagnose IA. Galactomannan, β-D glucan test, and DNA detection in IA are available only in a few centers. Mortality of the patients with IA is very high due to delays in diagnosis and therapy. Antifungal use is largely restricted to amphotericin B deoxycholate and itraconazole, though other anti-Aspergillus antifungal agents are available in those countries. Clinicians are aware of good outcome after use of voriconazole/liposomal amphotericin B/caspofungin, but they are forced to use amphotericin B deoxycholate or itraconazole in public-sector hospitals due to economic reasons.

Candida infective endocarditis: report of 15 cases from a prospective multicenter study

Candida species are an uncommon cause of infective endocarditis (IE). Given the rarity of this infection, the epidemiology, prognosis, and optimal therapy of Candida IE are poorly defined. We conducted a prospective, observational study at 18 medical centers in Italy, including all consecutive patients with a definite diagnosis of IE admitted from January 2004 through December 2007.A Candida species was the causative organism in 8 cases of prosthetic valve endocarditis (PVE), 5 cases of native valve endocarditis (NVE), 1 case of pacemaker endocarditis, and 1 case of left ventricular patch infection. Candida species accounted for 1.8% of total cases, and for 3.4% of PVE cases. Most patients (86.6%) had a health care-associated infection. PVE associated with a health care contact occurred after a median of 225 days from valve implantation. Ten patients (66.6%) were treated with caspofungin alone or in combination with other antifungal drugs. The overall mortality rate was 46.6%. Mortality was higher in patients with PVE (5 of 8 cases, 62.5%) than in patients with NVE (2 of 5 patients, 40%). A better outcome was observed in patients treated with a combined medical and surgical therapy.Candida IE should be classified as an emerging infectious disease, usually involving patients with intravascular prosthetic devices, and associated with substantial related morbidity and mortality. Candida PVE usually is a late-onset disease, which becomes clinically evident even several months after an initial episode of transient candidemia.

Pediatric invasive aspergillosis: a multicenter retrospective analysis of 139 contemporary cases

OBJECTIVE

Invasive aspergillosis is a major cause of morbidity and mortality in immunocompromised children. Invasive aspergillosis has been well characterized in adults; however, the incidence and analysis of risk factors, diagnostic tools, treatments, and outcomes have not been well described for a large cohort of pediatric patients.

METHODS

We conducted the largest retrospective review of contemporary cases of proven and probable pediatric invasive aspergillosis diagnosed at 6 major medical centers (January 1, 2000, to July 1, 2005).

RESULTS

Aspergillus fumigatus was the species most frequently recovered (52.8%) for the 139 patients analyzed. The majority of the children had a malignancy with or without hematopoietic stem cell transplant. Significant risk factors that impacted survival were immunosuppressive therapies and allogeneic stem cell transplant. The most common clinical site of invasive aspergillosis was the lungs (59%), and the most frequent diagnostic radiologic finding was nodules (34.6%). Only 2.2% of children showed the air crescent sign, 11% demonstrated the halo sign, and cavitation was seen in 24.5% of patients. Before the diagnosis of invasive aspergillosis, 43.1% of patients received fluconazole, and 39.2% received liposomal amphotericin B. After the diagnosis of invasive aspergillosis, 57% were treated with a lipid formulation of amphotericin B; however, 45.8% received > or = 3 concomitant antifungal agents. Analysis did not show superiority of any 1 antifungal related to overall mortality. A total of 52.5% (73 of 139) died during treatment for invasive aspergillosis. Of all the interventions implemented, surgery was the only independent predictor of survival.

CONCLUSIONS

Our analyses revealed common findings between adult and pediatric invasive aspergillosis. However, one key difference is diagnostic radiologic findings. Unlike adults, children frequently do not manifest cavitation or the air crescent or halo signs, and this can significantly impact diagnosis. Immune reconstitution, rather than specific antifungal therapy, was found to be the best predictor of survival.

Fungal infections of the heart: A clinicopathologic study of 50 autopsy cases

Cardiac fungal infection (CFI) is relatively uncommon, but its incidence is increasing. It is associated with a grim prognosis, but some CFI patients can survive given an early diagnosis and aggressive therapy. To clarify the clinicopathologic features of CFI, a retrospective autopsy study was conducted. Among a total of 4396 autopsy cases collected over a 33-year period (1973-2005), 50 CFI patients (1.1%) were selected and studied clinicopathologically. The study subjects were 32 males and 18 females with a mean age of 65.5 years. Underlying diseases for CFI included solid malignant neoplasms (n=23), hematologic disorders (n=10), chronic renal diseases (n=7), liver diseases (n=5), diabetes mellitus (n=5), and other miscellaneous ailments. Antibiotics were given to 47 patients, while corticosteroids, antineoplastic drugs, and antifungal agents were used for 21, 12, and 12 patients, respectively. None of the patients was diagnosed to have CFI antemortem. Most patients (n=45) demonstrated multi-organ fungal infections with myocardial involvement. Causative pathogens were Candida (n=36), Aspergillus (n=9), Mucor (n=4), and Cryptococcus (n=1). Comparisons between previous CFIs (1973-1989) and recent CFIs (1990-2005) revealed an increasing proportion of non-candidal CFIs (p=0.004) in the latter. Our results point to the clinical importance of defining diagnostic criteria and therapeutic strategies for CFIs, especially for non-candidal CFIs.

The modern autopsy: what to do if infection is suspected

Deaths due to infectious diseases are common worldwide. The autopsy, although less frequently performed than previously, is important to our understanding of disease pathogenesis. The autopsy also provides critical information regarding potential disease outbreaks. To optimize the benefits of an autopsy, the pathologist should approach the autopsy with a well-constructed differential diagnosis that provides the framework for appropriate selection of diagnostic specimens and tests. Standard microbiologic cultures, although necessary and important, are often insufficient and must be supplemented by newer molecular methodologies.