Cellulosimicrobium cellulans has been reported as a rare cause of human pathogenesis. Infections mainly occur in immunocompromised patients and very often are associated with a foreign body. We report the first case of septic arthritis caused by C. cellulans in an immunocompetent patient. Our patient suffered a penetrating palm tree thorn injury to his left knee 8 weeks before admission. Although no foreign objects were found, they were suspected because previous reports suggest a frequent association with this microorganism, and open debridament was performed. Removal of foreign bodies related to this organism must be considered a high-priority treatment in these patients to achieve a complete recovery.
CASE REPORTAn 81-year-old man was admitted to our department with a 6-day history of pain, loss of motion, erythema, and swelling in his left knee. His past medical history was significant for gout, mild mitral regurgitation, hypertension, and moderate chronic renal insufficiency, and 8 weeks previously he had been admitted to our department with septic arthritis of the same knee caused by Pantoea agglomerans after suffering a penetrating injury to his left knee with a palm tree thorn, with good response to treatment with intravenous ceftriaxone (1 g per day for 15 days) and levofloxacin (250 mg per day for 15 days).Physical examination showed an afebrile patient with a painful, warm, swollen, and tender left knee. Limitation of active and passive range of motion were also noted. Otherwise, the examination was unremarkable. Laboratory tests showed an elevated serum C-reactive protein (CRP) level (17 mg/dl; normal, Ͻ0.5) with a normal blood cell count. Arthrocentesis yielded 30 ml of yellowish fluid. Direct microscopic examination of the synovial fluid revealed many leukocytes, and crystal analysis with compensated polarized light was negative. Gram stain was negative, and empirical treatment with levofloxacin was started intravenously (500-mg initial dose and then 250 mg every 24 h, with creatinine clearance of 40 ml/min because of renal failure,). Three days after admission, a Gram-positive rod grew in synovial cultures and was subsequently identified as Cellulosimicrobium cellulans. Identification was initially made by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) (Bruker Daltonics) and later confirmed by a semiautomatic culture system (Vitek-II). The microorganism recovered was fully susceptible to vancomycin (MIC, 1 g/ml) and linezolid (MIC, 1 g/ml) and showed intermediate susceptibility to tetracyclines (MIC, 4 g/ml) and levofloxacin (MIC, 3 g/ml). The isolate was interpreted as a contaminant, so we continued therapy with levofloxacin.Three days later, due to the persistence of symptoms, the high levels of CRP (23.49 mg/dl), and a high erythrocyte sedimentation rate (ESR) (99 mm/h; normal, Ͻ13 mm/h), a new arthrocentesis was performed, and C. cellulans was again isolated. Linezolid was added based on the lack of response to treatment and suspicion of antibiotic-...
