Cardiac infections in the immunosuppressed patient

Fungal Endocarditis: An Autopsy Study

Between 1990 and 2002, 237 hearts were examined at autopsy, including 16 with infective endocarditis; 6 showed fungal endocarditis. The preceding pathology was chronic rheumatic heart disease in 2 patients, one of whom had undergone double valve replacement, 2 patients had been treated for acute lymphoblastic leukemia, and one had protein-energy malnutrition. The underlying cause was unknown in one case. The organisms isolated were Aspergillus in 3 patients, Zygomycota in 1, Candida in 1, and both Candida tropicalis and Aspergillus in 1 patient. Immunosuppressed states are a cause of fungal endocarditis in India, although chronic rheumatic heart disease is the preceding pathology in the majority of patients.

Assessing bacterial invasion of cardiac cells in culture and heart colonization in infected mice using Listeria monocytogenes

Listeria monocytogenes is a Gram-positive facultative intracellular pathogen that is capable of causing serious invasive infections in immunocompromised patients, the elderly, and pregnant women. The most common manifestations of listeriosis in humans include meningitis, encephalitis, and fetal abortion. A significant but much less documented sequelae of invasive L. monocytogenes infection involves the heart. The death rate from cardiac illness can be up to 35% despite treatment, however very little is known regarding L. monocytogenes colonization of cardiac tissue and its resultant pathologies. In addition, it has recently become apparent that subpopulations of L. monocytogenes have an enhanced capacity to invade and grow within cardiac tissue. This protocol describes in detail in vitro and in vivo methods that can be used for assessing cardiotropism of L. monocytogenes isolates. Methods are presented for the infection of H9c2 rat cardiac myoblasts in tissue culture as well as for the determination of bacterial colonization of the hearts of infected mice. These methods are useful not only for identifying strains with the potential to colonize cardiac tissue in infected animals, but may also facilitate the identification of bacterial gene products that serve to enhance cardiac cell invasion and/or drive changes in heart pathology. These methods also provide for the direct comparison of cardiotropism between multiple L. monocytogenes strains.

Genome sequence of Listeria monocytogenes 07PF0776, a cardiotropic serovar 4b strain

Listeria monocytogenes is a food-borne bacterial pathogen commonly associated with serious invasive infections of the central nervous system or of the developing fetus. We present the genome sequence of Listeria monocytogenes 07PF0776, a serovar 4b isolate from a human myocardial abscess that exhibits enhanced invasion of cardiac tissue.

Evidence for subpopulations of Listeria monocytogenes with enhanced invasion of cardiac cells

Cardiac infections caused by the foodborne bacterium Listeria monocytogenes represent a significant but poorly studied facet of disease. It is not known whether L. monocytogenes cardiac infections stem solely from host susceptibility, or whether bacterial isolates exist that exhibit a tropism for cardiac tissue. Here we examine the cardio-invasive capacity of a recent L. monocytogenes cardiac case strain (07PF0776) as well as nine additional outbreak and clinical isolates. Mice infected with the cardiac isolate 07PF0776 had 10-fold more bacteria recovered from heart tissue than those infected with L. monocytogenes strain 10403S, a well-characterized clinical isolate originally obtained from a human skin lesion. Additional L. monocytogenes isolates exhibited varied capacities to colonize the hearts of mice; however, those with the highest efficiency of mouse cardiac invasion also demonstrated the highest levels of bacterial invasion in cultured myoblast cells. Our findings strongly suggest that subpopulations of L. monocytogenes strains have acquired an enhanced ability to target and invade the myocardium.

Biatrial aspergillosis in a patient with immunocompetency

A 24-year-old man presented with a 24-hour history of pain and numbness in his left arm. The patient's clinical presentation of peripheral embolism was corroborated by angiography. Echocardiographic study showed masses in both right and left atria. Pathologic specimen from the embolus confirmed the diagnosis of aspergillosis.