Community acquired methicillin resistant staphylococcus aureus pneumonia

Case contributed by Callum Smith


Fevers, productive cough and hemoptysis on a background of recent intravenous drug use. There was no history of travel or exposure to tuberculosis.

Patient Data

Age: 30 years
Gender: Male

Right middle lobe consolidation with an associated cavitating lesion and air bronchogram. There is a small right sided pleural effusion. The remainder of the lung fields are unremarkable. There are no abnormalities of the mediastinal structures, bones or soft tissues.

Case Discussion

A 30 year old man presented with 2 days of fevers, productive cough and hemoptysis on a background of recent intravenous drug use. Three induced sputum specimens were obtained. Methicillin resistant staphylococcus aureus (MRSA) was cultured in two of the three specimens. All three were negative for acid fast bacilli. The patient was treated with a course of intravenous vancomycin followed by oral trimethoprim/sulphamethoxazole.

Community acquired MRSA pneumonia most commonly occurs post influenza in young and previously healthy patients. It is associated with a high mortality and should be suspected in patients with a prodrome of flu like symptoms, hemoptysis, high fevers, multilobar infiltrates with cavitation on chest x-ray or a history of intravenous drug use. Although community acquired MRSA pneumonia is frequently bilateral, as in this case it can be unilateral. 

MRSA pneumonias were previously predominantly nosocomial infections. However, since the 1990s MRSA has emerged as a community acquired pathogen. It most commonly causes skin and soft tissue infections. Community acquired MRSA pneumonia is uncommon and has an incidence between 100-1000 per 100000 and 75-85% of patients require admission to the intensive care unit 1-4

Fortunately, this patient was successfully treated on the respiratory ward and did not require admission to the intensive care unit. 

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