Expect the unexpected: endocarditis caused by Legionella feeleii.

Area of Science:

• Infectious Diseases
• Transplant Surgery
• Clinical Microbiology

Background:

• Legionella feeleii is an uncommon cause of Legionnaires' disease.
• Endocarditis is a rare but serious infection of the heart valves.
• Lung transplant recipients are immunocompromised, increasing susceptibility to opportunistic infections.

Observation:

• A fatal case of Legionella feeleii endocarditis was observed in a patient post-lung transplant.
• The diagnosis was significantly delayed.
• Standard microbiological tests failed to identify the pathogen promptly.

Findings:

• Routine microbiological testing of nonrespiratory specimens does not adequately screen for extrapulmonary Legionella.
• Urine antigen testing is primarily effective for Legionella pneumophila serogroup 1, missing other species like L. feeleii.
• Molecular sequencing proved crucial for diagnosing this case of blood culture-negative endocarditis.

Implications:

• Clinical microbiology protocols need enhancement to detect diverse Legionella species beyond L. pneumophila in nonrespiratory samples.
• Diagnostic strategies for post-transplant patients should consider a broader range of pathogens and testing modalities.
• Molecular sequencing offers a valuable tool for diagnosing challenging cases, particularly blood culture-negative endocarditis.