Lung - Staphylococcus aureus Abscesses - Erler Zimmer
Clinical History
A 55-year-old woman presents with severe dyspnea, a productive cough, and oral candidiasis. She is immunosuppressed due to a history of rheumatoid arthritis, treated with steroids and cyclophosphamide. Sputum cultures revealed the growth of Staphylococcus aureus. Despite appropriate therapy initiation, she unfortunately passed away shortly after admission.
Pathology
The right lung has been bisected, revealing multiple irregular abscess cavities. The largest, located in the apex of the lower lobe, measures 4 x 3 cm in diameter. Another irregular abscess cavity is present at the apex of the upper lobe, approximately 3 x 2 cm in diameter, surrounded by a zone of consolidation. Several small abscesses are also observed. Patchy consolidation is noted in the middle lobe. Numerous bronchi contain and are obstructed by pus plugs. Cultures from the specimen grew Staph. aureus. This serves as an example of multiple Staphylococcal lung abscesses in an immunosuppressed patient.
Further Information
Staphylococcus aureus, a gram-positive coccus, is part of the human body's microbiota, commonly found on the skin or upper respiratory tract. While usually commensal, it can cause opportunistic infections, including skin infections and, less frequently, pneumonia and endocarditis. Staphylococcus aureus can lead to both community and hospital-acquired pneumonia, with the latter often associated with intubation and prolonged admissions. The prevalence of Methicillin-Resistant Staph Aureus (MRSA) causing hospital-acquired pneumonia is on the rise.
Staph Aureus pneumonia is a significant cause of secondary bacterial pneumonia post-viral respiratory infections, like post-influenza. Intravenous drug users face an increased risk of developing 'metastatic' Staph. aureus pneumonia and endocarditis due to staph bacteremia resulting from the use of unclean needles. Staph. aureus pneumonia is severe and linked to a higher complication rate, including cavitating abscess formation and empyema.
Clinical suspicion of Staph. Aureus pneumonia should arise in high-risk groups and patients with pneumonia exhibiting rapid deterioration, hemoptysis, early multilobar pneumonia on X-ray, pulmonary cavitation, or disseminated intravascular coagulation. First-line treatment for Staph. aureus pneumonia involves penicillin antibiotics, such as flucloxacillin. Given the common penicillin resistance with penicillinase production (e.g., MRSA), MRSA is treated with glycopeptide antibiotics like vancomycin or oxazolidinone antibiotics such as linezolid.
