Suspected Legionella-Induced Perimyocarditis in an Adult in the Absence of Pneumonia

Abstract

Legionella infection can manifest itself in many clinical forms, most commonly as pneumonia, but rarely in the form of myocardial involvement. Legionella with myocardial involvement independent of pneumonia is almost never seen in the adult population and therefore is cited only a handful of times in the medical literature. When reported, Legionella carditis itself typically occurs as an isolated pericarditis with effusion. Cases of isolated Legionella with myocardial involvement, but without associated pneumonia, have been reported among children. To our knowledge, there are no reported cases of Legionella myocarditis and pericarditis presenting concurrently with or without pneumonia, in either an adult or a pediatric population.

Herein, we report a rare manifestation of Legionella pneumophila-induced perimyocarditis (strongly suspected, if not incontrovertibly proved) in an adult, in the absence of pneumonia.

Legionella infection can manifest itself in many different clinical presentations—most commonly as pneumonia, but rarely as myocardial involvement. The severity of illness at presentation varies from mild, nonspecific findings to profound respiratory or multiorgan failure. Extrapulmonary legionellosis is rare; but when extrapulmonary manifestation does occur, its most common site of infection is the heart, especially in the pediatric population.¹ Legionella carditis is rarely seen independent of pneumonia in the adult population and is more commonly observed in pediatric patients.² Herein, we report a case of suspected perimyocarditis, a rare manifestation of Legionella pneumophila in an adult, in the absence of pneumonia.

Case Report

A 50-year-old black woman with a history of diabetes mellitus, chronic obstructive pulmonary disease, and hypertension presented with 1 week's duration of nonproductive cough, increasing fatigue, exertional dyspnea, and atypical chest discomfort. Initial and repeat chest radiographs were negative for infiltrates suggestive of pneumonia (Fig. 1). Cardiac biomarkers were markedly elevated, and the electrocardiogram was suggestive of an acute myocardial injury pattern: ST-segment elevation in the anterolateral leads. On the basis of these findings, the patient underwent emergent coronary angiography, which showed angiographically normal coronary vessels. Transthoracic echocardiography (Fig. 2) demonstrated normal left ventricular size and function and a mild pericardial effusion. Consequently, the patient was placed on a nonsteroidal anti-inflammatory agent for a presumptive diagnosis of perimyocarditis. During the next 48 hours, the patient developed spiking fevers, profound hypotension, and eventually multiorgan failure, which required mechanical ventilation, vasopressor support, and hemodialysis. Serial cultures and radiographic findings failed to reveal either a locus of infection or a pathogen despite the patient's persistent leukocytosis and high fever while on empiric intravenous antibiotic agents. An extensive battery of diagnostic tests to reveal the cause of her clinical deterioration yielded inconclusive results regarding the presence of a metabolic, autoimmune, or connective-tissue disease, or of an infectious-disease process. A repeated echocardiographic evaluation 5 days later showed moderate global systolic impairment in left ventricular function (estimated ejection fraction, 0.35). At this point, we ordered a urinary Legionella antigen, which was positive for L. pneumophila, serogroup 1 antigen. The antibiotic agent was switched to intravenous moxifloxacin hydrochloride, and over the next 5 days the patient's clinical status improved. A urinary antigen test repeated 10 days after switching antibiotics was negative for L. pneumophila, serogroup 1 antigen. The patient was eventually discharged from the hospital in improving condition 28 days after her admission, diagnosed with presumed Legionella perimyocarditis.

Fig. 1. Initial upright chest radiograph taken on the day of the patient's admission was negative for infiltrates suggestive of pneumonia. Thereafter, serial chest radiographs remained negative for the presence of infiltrates and for an indication of a source of infection.

Fig. 2. A) Two-dimensional transthoracic echocardiogram (subcostal view) shows a small pericardial effusion without hemodynamic significance surrounding the right ventricle in systole (arrows). B) Parasternal short-axis view of the left ventricle shows a small posterior pericardial effusion in systole (arrows).

Discussion

Gross and colleagues³ in 1981 reported the 1st case of Legionella myocarditis as a sequela to Legionella pneumonia; since then, there have been only 5 documented adult cases, all of which had a concomitant pneumonia without pericardial involvement.^2–7 There have been previous reports of Legionella pericarditis with or without pneumonia, but those cases did not have direct, documented myocardial involvement.⁸ There is awareness of an expanding clinical spectrum for the cardiac manifestation of Legionella disease: cardiac involvement may present as pericarditis, myocarditis, endocarditis, and even dysrhythmias.⁵ We believe that ours, however, is the 1st reported case of perimyocarditis in the absence of pneumonia.

In adults, legionellosis is responsible for approximately 2% to 15% of all cases of community-acquired pneumonia that require hospitalization.⁹ Transmission occurs through the aspiration of an aerosol that has been contaminated with the Legionella organism. Moreover, superficial wounds can become infected through contact with contaminated water.⁹ Our patient would later recall routine visits to her local health-club spa over the 12 weeks preceding her admission.

Legionella urinary antigen testing has an excellent combined sensitivity (90%) and specificity (100%), second only to culture (sensitivity, 95%; specificity, 100%) for diagnosing legionellosis. The urinary antigen test has several advantages over culture: it is the more rapid, less expensive, and easier test—free of the difficulty of obtaining the sometimes inaccurate sputum samples—and its sensitivity is not reduced by previous antibiotic treatment. The Centers for Disease Control and Prevention (CDC) recommend the urinary antigen for clinical laboratory use; and it is the only test (other than culture) for confirming a diagnosis of pulmonary or extra-pulmonary legionellosis.^10,11 Although we believed that invasive tests, including pericardiocentesis or myocardial biopsy, would have strengthened the diagnosis, we decided not to proceed with them because they carry the risk of complication without a change in management and would not have altered a diagnosis already supported by CDC guidelines. The dramatic recovery after the change in antibiotic agents gave our diagnosis strong clinical affirmation, without subjecting the patient to potential adverse sequelae.

Diabetes mellitus, smoking, chronic lung disease, exposure to hot tubs, and a weakened immune system are some of the recognized risk factors for legionellosis in adults.¹² All of these were present in our patient, which placed her at an increased risk for legionellosis. Legionella disease with sole myocardial involvement, however, is an extremely rare clinical presentation that is cited fewer than half a dozen times in the medical literature. It occurs too rarely to enable the identification of additional predictors of disease susceptibility.

The prognosis of Legionella carditis seems to correlate with the severity of systemic involvement and patient comorbidities. Patients with isolated extrapulmonary manifestation do well when the condition is recognized early and treated promptly with appropriate antibiotic agents. Early initiation of appropriate therapy in cases of isolated cardiac involvement can result in complete normalization of physical and electrocardiographic findings and in full recovery of left ventricular function.^2–5

In adults, Legionella carditis invariably presents with pneumonia.¹ In contrast, cases of isolated Legionella myocardial involvement without associated pneumonia have been reported among children.² The pathophysiology for this “age-to-organ-specific” clinical manifestation may be explained by the different set of risk factors for adults: adults with significant smoking histories are prone to the development of chronic lung disease and, consequently, to pulmonary involvement in the event of legionellosis.

We believe that Legionella should be considered in the differential diagnosis and workup for patients who present with unexplained myocarditis or pericarditis, especially if they have multiple risk factors for legionellosis. Early recognition is crucial to ensure full recovery from this form of reversible carditis, because the treatment is different from that for other forms of carditis and can be quite effective with early initiation of appropriate antibiotic medication.