A Case of Pyogenic Spondylitis Due toAggregatibacter aphrophilus

Abstract

Aggregatibacter aphrophilus, a normal component of oral cavity flora, mostly causes infective endocarditis and only rarely causes spondylitis; no spondylitis cases have been previously reported in Korea. We report a case of pyogenic spondylitis due to A. aphrophilus without endocarditis. A 64-year-old man was admitted for back pain lasting 3 weeks. There was severe tenderness on lumbar spines but no fever. Laboratory evaluation showed leukocytosis and elevated C-reactive protein. Blood cultures were negative. Magnetic resonance imaging showed psoas abscess and vertebral inflammation. Pus was obtained by computerized tomography-guided aspiration from the psoas abscess and inoculated into blood culture bottles. After 5 days of incubation, growth was detected: the isolate was a Gram-negative short rod bacteria identified as A. aphrophilus by the automated system; this was confirmed by 16S ribosomal RNA sequencing. There was no evidence of endocarditis in echocardiography and retinal examination. Back pain persisted despite 8 weeks of antibiotic treatment, so vertebral corpectomy was performed. A. aphrophilus, a rare cause of pyogenic spondylitis, can induce spondylitis without endocarditis. If a patient with pyogenic spondylitis shows negative routine bacterial cultures, fastidious organisms such as A. aphrophilus should be suspected and the blood culture bottles could be used. (Ann Clin Microbiol 2014; 17:99-103)