Conservative management of a brain abscess in a patient with Staphylococcus lugdunensis endocarditis

Brain abscess is defined as a focal, intracerebral infection that begins as a localized area of cerebritis and develops into a collection of pus surrounded by a well-vascularized capsule. Microorganisms can gain access to the brain through several mechanisms, most commonly by direct extension of an adjacent suppurative focus (i.e. otitis media, mastoiditis, or sinusitis) or by direct penetration via an open cerebrospinal fluid leak (e.g. after cranial fracture or neurosurgical complication). Another mechanism of brain abscess formation is hematogenous bacterial spread from a distant focus of infection, such as endocarditis. Despite the presence of continuous bacteremia, brain abscess is an uncommon complication after bacterial endocarditis [1] (less than 5% of cases in most series). However, endocarditis due to Staphylococcus lugdunensis follows a more fulminant course, typically resulting in either cardiac complications or systemic emboli with metastatic foci of infection. Optimal handling of patients with bacterial infections of the central nervous system often requires surgical management; nonetheless, a subset of patients may be treated with appropriate antimicrobial therapy alone [2–4]. In this setting, the choice of antibiotic agents should be based on the results of susceptibility testing and the drug’s cerebrospinal fluid penetration. Here, we report a case of brain abscess in a patient with S. lugdunensis endocarditis involving a native bicuspid aortic valve. We also review the literature regarding the conservative management of brain abscesses in this clinical setting. A 49-year-old woman with an unremarkable medical history was admitted to our hospital with fever of 39°C, right-sided hemiparesis and aphasia. Computed tomography (CT) scan of the brain suggested an ischemic lesion of the left external capsule. S. lugdunensis was isolated from all four of the blood cultures taken upon admission. The organism was shown to be susceptible to all antibiotics tested. A transesophageal echocardiograph (TEE) confirmed the presence of large vegetations (12×4 mm) on the bicuspid aortic valve and subsequent regurgitation due to aortic valve destruction. The diagnosis of endocarditis due to S. lugdunensis involving a bicuspid aortic valve with severe aortic valve insufficiency and embolic septic cerebrovascular insult was established. Antibiotic therapy with flucloxacillin (2 g iv q4h), supplemented with gentamicin (80 mg iv tid) for the first 5 days, was started. Body temperature, neurological deficiencies and inflammatory laboratory values normalized rapidly and the patient remained hemodynamically stable. After 6 weeks of antibiotic therapy, TEE showed persistent aortic valve vegetation and an increased diastolic diameter of the left ventricle (EDVI: 63 ml/m). Valve replacement was subsequently recommended. A second CT scan (Fig. 1) performed during the pre-operative investigation revealed the presence of a small abscess (1 cm in diameter) at the level of the left insula. Given the size of the abscess, the lack of neurological symptoms and the known tendency toward development of metastatic lesion secondary to S. lugdunensis bacteremia, surgical abscess excision was deferred. Because of its optimal ability to penetrate the blood brain barrier, rifampin (600 mg orally bid) was added to the antibiotic regimen. Eur J Clin Microbiol Infect Dis (2006) 25:476–478 DOI 10.1007/s10096-006-0169-0