A 12-year-old child developed meningitis 6 days after a third ventriculostomy by endoscopy. A coagulasenegative Staphylococcus sp. was isolated in pure culture from the cerebrospinal fluid and was definitely identified as Staphylococcus lugdunensis after the 16S ribosomal DNA gene and rpoB gene were sequenced. This report describes the first case of S. lugdunensis meningitis.There is only one report of Staphylococcus lugdunensis (4), a coagulase-negative organism, causing an opportunistic infection of the central nervous system; the organism was isolated from a brain abscess but not in pure culture (3). Here we describe the isolation of S. lugdunensis from a patient with meningitis; the organism was isolated in pure culture and characterized by molecular methods.A 12-year-old male underwent a third ventriculostomy by endoscopy for the treatment of congenital obstructive hydrocephalus. An intravenous catheter was placed for anesthesia, and the endoscopy was performed with prophylactic oxacillin at 100 mg/kg of body weight. The child recovered uneventfully from the surgery; the intravenous catheter was removed after 24 h, and the patient was discharged 72 h after the surgery. Three days after leaving the hospital, the patient was readmitted with an intense headache, vomiting, and lethargy. Abnormal findings on physical examination were fever (39.5°C) and meningitis rigidity in the absence of localizing signs. The trepanation site was unremarkable, and cardiac auscultation and echocardiography results were normal. Laboratory results showed a leukocyte count of 17,700 cells/l with 82% being polymorphonuclear cells, a platelet count of 348,000 cells/l, a C-reactive protein level of 140 mg/liter, and an erythrocyte sedimentation rate of 60 mm after 1 h. Three blood samples for aerobic cultures were drawn, and cerebrospinal fluid (CSF) was obtained by lumbar puncture. Examination of the CSF showed 600 leukocytes/l with 60% of the cells being polymorphonuclear. There were no visible erythrocytes, but there were approximately 5 to 10 gram-positive cocci per microscope field (magnification, ϫ400). The protein concentration in the CSF was elevated at 0.85 mg/dl, and the glucose concentration was 2.2 mmol/liter. Cultures of the CSF and all the blood samples on 5% sheep blood agar (bioMérieux, La Balme les Grottes, France) at 37°C produced slightly yellow-pigmented colonies of catalase-positive cocci with positive agglutination for the fibrinogen affinity factor (Staphaurex agglutination test; Murex Diagnostics, Darford, United Kingdom). Tube coagulase tests using rabbit plasma were negative, and the API 32 STAPH identification strip (bioMérieux) identified the isolates as S. lugdunensis. We found 100% homology in the 16S ribosomal DNA gene sequences of the isolates and S. lugdunensis (GenBank accession number AB009941), and a partial sequence of the rpoB gene of each of the isolates was identical to that of S. lugdunensis type strain CIP 103642 (Pasteur Institute Collection, Paris, France) (1). The isolates were tested by t...