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Pneumonia due to Legionella micdadei in bone marrow transplant recipients
J R Schwebke1, R Hackman, R Bowden
1Department of Medicine, University of Washington, Seattle.
Abstract:
Legionella micdadei has previously been described as a cause of nosocomial pneumonia, particularly in kidney transplant recipients. Cell-mediated immunity is the principal host defense against this pathogen. A common clinical scenario in the immunocompromised host is that of septic pulmonary embolus, but asymptomatic infections have also been reported. The organism is weakly acid-fast in clinical specimens but loses this property when grown on solid media. We report two cases of L. micdadei pneumonia, differing markedly in clinical severity and outcome, in bone marrow transplant recipients. Additionally, we note the growth of the organism in liquid culture media with preservation of its acid-fast property.
Insights
Legionella micdadei can cause pneumonia in immunocompromised patients, especially bone marrow transplant recipients. This study highlights varied clinical presentations and notes the organism retains its acid-fast property in liquid culture.
Area of Science:
- Medical Microbiology
- Immunology
- Infectious Diseases
Background:
- Legionella micdadei is a known cause of nosocomial pneumonia, particularly affecting kidney transplant recipients.
- Cell-mediated immunity is crucial for host defense against Legionella species.
- Immunocompromised individuals are at higher risk for severe Legionella infections, including septic pulmonary emboli.
Observation:
- Two cases of Legionella micdadei pneumonia in bone marrow transplant recipients are presented, exhibiting significant differences in clinical severity and patient outcomes.
- The organism demonstrated variability in its acid-fast staining property: weakly acid-fast in clinical specimens but losing this characteristic upon growth in solid media.
- Notably, Legionella micdadei retained its acid-fast property when cultured in liquid media.
Findings:
- Legionella micdadei pneumonia presents with diverse clinical manifestations and outcomes in immunocompromised hosts.
- The acid-fast staining characteristic of Legionella micdadei is dependent on the culture medium used.
- Liquid culture media facilitates the preservation of the acid-fast property of Legionella micdadei.
Implications:
- Understanding the varied clinical spectrum of Legionella micdadei infections is vital for timely diagnosis and management in transplant recipients.
- The preservation of the acid-fast property in liquid culture may aid in the laboratory identification of Legionella micdadei.
- Further research into host-pathogen interactions and diagnostic markers for Legionella micdadei in immunocompromised populations is warranted.