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The clinical spectrum of Staphylococcus aureus pulmonary infection
M G Kaye1, M J Fox, J G Bartlett
1Department of Medicine, Northwestern University, Chicago.
Abstract:
Staphylococcus aureus causes serious pulmonary infections in adults. Prior descriptions of this entity have depended on diagnosis of expectorated sputum cultures that are often contaminated. To better characterize this infection, we retrospectively reviewed the medical records of 31 adults with S aureus pulmonary infection diagnosed by culture specimens uncontaminated by the upper respiratory flora. Our results support the concept that S aureus pulmonary infections usually occur in older adults (sixth decade or older) with concomitant illnesses that are typically nosocomial. However, in contrast to previous reports, the chest roentgenograms in these patients typically showed multilobar infiltrates (60 percent), predominantly in the lower lobes (64 percent), and often bilateral (48 percent). Pleural involvement (48 percent) was more common than previously reported, and abscess formation (16 percent) occurred infrequently. Sputum cultures were found to be sensitive but nonspecific diagnostic tools. Despite antibiotic therapy, reinfection occurred in 10 percent of patients and the mortality rate was 32 percent.
Insights
Staphylococcus aureus pulmonary infections primarily affect older adults and often present with multilobar infiltrates on chest X-rays. This serious bacterial infection has a significant mortality rate, even with treatment.
Area of Science:
- Pulmonary Medicine
- Infectious Diseases
- Radiology
Background:
- Staphylococcus aureus is a significant cause of severe adult pulmonary infections.
- Previous characterizations relied on potentially contaminated sputum cultures.
- Accurate diagnosis and characterization are crucial for effective management.
Purpose of the Study:
- To better characterize Staphylococcus aureus pulmonary infections in adults.
- To identify typical clinical and radiological features.
- To assess diagnostic utility of sputum cultures and treatment outcomes.
Main Methods:
- Retrospective review of medical records for 31 adult patients.
- Inclusion criteria: S. aureus pulmonary infection diagnosed by uncontaminated culture specimens.
- Analysis of clinical data, chest roentgenograms, and treatment outcomes.
Main Results:
- Infections predominantly occurred in older adults (≥60 years) with comorbidities, often nosocomial.
- Chest X-rays frequently revealed multilobar (60%), lower lobe (64%), and bilateral (48%) infiltrates.
- Pleural involvement (48%) was common; abscess formation (16%) was infrequent. Mortality rate was 32%.
Conclusions:
- S. aureus pulmonary infections in adults have distinct radiological patterns, including multilobar and bilateral infiltrates.
- Sputum cultures are sensitive but not specific for diagnosis.
- High mortality and risk of reinfection underscore the severity of these nosocomial infections.