Study of Two Cases of Fatal Necrotizing Pneumonia in Healthy Adults, Due to Staphylococcus Aureus Infection. Is It Always Penton-Velentine Leukocidin?
VB Korcheva, E Goranson, N Gordon, P Stenzel. Oregon Health and Science University, Portland, OR
Background: Necrotizing pneumonia due to community acquired methicillin resistant Staphylococcus aureus (MRSA) is reported with increasing frequency in healthy individuals. Most of the cases in the USA are attributed to USA 300 MRSA-clone which carries genes, encoding Panton-Valentine leukocidin (PVL) and are often associated with influenza or influenza-like illnesses. PVL is a leukotoxin which acts on human neutrophils, monocytes, and macrophages by inducing massive release of inflammatory mediators. It has been suggested that PVL has a major role in the inflammation and necrosis of the respiratory epithelium and parenchyma in the course of MRSA-associated necrotizing pneumonia. We report two cases of fatal necrotizing pneumonia with nearly identical clinical presentations and autopsy findings, but different etiologies.
Design: We reviewed the clinical and pathologic results from two autopsy cases of necrotizing pneumonia that occurred at OHSU. Fresh lung tissue was sent to a regional laboratory for routine microbiology and viral cultures and to the Oregon Public Health Division (OPHD) for toxin studies, including PVL and toxic shock syndrome toxin 1 (TSST-1).
Results: Previously healthy 18 year old male and 54 year old female presented to local hospitals with histories of sore throat, chills, and fever. Chest radiographs were unremarkable. Both patients were thought to have viral respiratory illness and were discharged home. Within 24 hours, both patients deteriorated and were admitted with hemoptysis, acute respiratory failure, severe metabolic acidosis, hypotension, and leukopenia. Despite resuscitation efforts, both patients expired within 12 hours after admission. Autopsy showed necrotizing pneumonia, associated with left sided cardiac hypertrophy. Microbiology studies demonstrated MRSA and Influenza A in the younger patient and methicillin-sensitive Staphylococcus aureus (MSSA) in the older patient. Toxin studies showed USA 300 producing PVL, negative for TSST-1 in the younger patient and USA 200 producing TSST-1, negative for PVL in the older patient.
Conclusions: We report two cases of fatal necrotizing pneumonia, associated with PVL producing MRSA and TSST-1 producing MSSA. PVL-associated necrotizing pneumonia has been increasingly reported in the literature in the last few years. To our best knowledge, cases of necrotizing pneumonia, associated with TSST-1 producing MSSA have been rarely reported in the literature.
Wednesday, March 11, 2009 1:00 PM
Poster Session VI # 6, Wednesday Afternoon