Enterococcal Empyema and Trapped Lung in Systemic Lupus Erythematosus

Sir,

Enterococci are facultative anaerobic Gram-positive cocci that very rarely cause lung infections.[1] Even rarer, enterococcal infection can cause empyema.[2] In patients with systemic lupus erythematosus (SLE), empyema due to Salmonella enteritidis, Mycobacterium tuberculosis, and Nocardia asteroides has been reported,[3] but Enterococcus has never been implicated.

A 23-year-old female with SLE presented with dyspnea, chest pain, and 2 weeks of fever and productive cough. There were absent breath sounds and dullness to percussion on the right hemithorax; investigations showed anemia, neutrophilia, and thrombocytopenia. Chest radiography confirmed a moderate pleural effusion and a concomitant right-sided pneumothorax. Tube thoracostomy resulted in purulent, malodorous drainage and fluid analysis confirmed empyema. On culture, there was heavy monomicrobial growth of Enterococcus. Despite drainage, the pneumothorax persisted over the next week [Figure 1a]. Computed tomography scanning confirmed persistent collapsed right lung and thickened visceral pleura [Figure 1b], leading to the diagnosis of trapped lung. The patient was treated with antibiotics and pulmonary decortication, with improved symptoms.

Figure 1.

(a) Chest radiograph and (b) computed tomography scan revealing persistent right-sided pneumothorax with visceral pleural thickening

Enterococcus does not commonly cause pulmonary infection. However, when infection due to Enterococcus does occur, it tends to be complicated.[4] Recently, a case of culture-negative empyema in SLE was described,[5] the first in the literature. However, it was noted that the patient received a dose of levofloxacin before thoracentesis. The second case with a similar diagnosis of sterile empyema in SLE has since been reported, but this patient also received levofloxacin before culture.[3] Grupper et al. have questioned whether enterococcal-associated respiratory infections are underdiagnosed due to the increased use of amoxicillin or fluoroquinolones.

Pneumothorax ex-vacuo or trapped lung has been described with complicated parapneumonic effusion. It is thought that chronic inflammation leads to the formation of a fibrous layer on the visceral pleura that prevents re-expansion. Although rare, empyema due to Enterococcus is a potentially life-threatening event in patients with SLE. Physicians must keep in mind this differential, and early thoracentesis with culture before antibiotic therapy is important. Finally, persistent pneumothorax after drainage in these patients must prompt the evaluation for visceral pleural thickening and pneumothorax ex-vacuo.

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Conflicts of interest

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