Thoracic Vertebral Osteomyelitis Caused byBurkholderia cepaciain an Immunocompetent Adult

Abstract

To the Editor: Apreviously healthy 71-year-old female complained of back pain 2 mo before admission to the hospital. She was a farmer and worked with vegetables and plants on a daily basis. A physical examination at the time of her admission revealed no remarkable findings except for local tenderness in her mid-thoracic region. Her body temperature on admission was 37.5 C. Laboratory examination demonstrated a white blood cell (WBC) count of 20,640/ mcL, with 80% segmented neutrophils, and a C-reactive protein concentration of 5.6 mg/dL. Plain radiographs of the patient’s spine revealed an osteolytic lesion of the T5 vertebral body. Magnetic resonance (MR) images of the thoracolumbar spine revealed a destructive lesion in the T5 and T6 vertebral bodies (Figs. 1A,B), which appeared as a hypointensity on T1-weighted MR images and a hyperintensity on T2-weighted MR images. Initially, cefazolin and gentamicin were prescribed. A computed tomography (CT)-guided biopsy of the T6 vertebral body was performed through the right pedicle of T6 on the day after the patient’s admission. Pathology examinations confirmed a chronic inflammatory reaction. Serial cultures of blood, urine, sputum, and biopsy tissues revealed no growth. Because of persistent fever and back pain, the patient was treated empirically with oxacillin 1.5 g q6h beginning on day four after her admission. The patient experienced persistent fever and weakness in her left leg, and more severe destructive osteomyelitis with epidural extension and cord compression were found on the MR images of her thoraco-lumbar spine (Fig. 2A). Decompression surgery, consisting of posterior laminectomies of T5 and T6 and a transpedicular biopsy, were done on day 18 of hospitalization. Tissue culture revealed no growth. The patient’s antibiotic therapy was then changed to ceftriaxone 2 g q12 h. However, progressive bilateral weakness of the patient’s lower limbs, and urinary retention were noted. Progressive extension of the epidural abscess, together with collapse of the T5–T6 vertebral bodies (which compressed the spinal cord) were demonstrated in MR images (Fig. 2B). The patient then underwent transthoracic corpectomies at T5 and T6, with internal fixation of an autologous bone graft (from the iliac crest) on day 36 after her first operation. Tissue culture confirmed Burkholderia cepacia infection. After antibiotic susceptibility tests showed the infecting organism to be sensitive to ceftazidime, meropenem, trimethoprim-sulfamethoxazole, and levofloxacin, the patient’s antibiotic therapy was changed again, to levofloxacin 250 mg q8h. However, her pulmonary compliance and function were poor after open chest surgery, and she succumbed about 2 wk after her second operation from septic shock and respiratory failure. Burkholderia cepacia, a gram-negative bacillus, is an important pathogen that infects patients particularly with cystic fibrosis (CF) and chronic granulomatous diseases, and immunocompromised patients [1,2]. This bacterium is found commonly in moist environments in association with soil, water, and plant roots [3]. The types of infection caused most commonly by B. cepacia are bacteremia, urinary tract infection, surgical site infection, septic arthritis, peritonitis, softtissue infection, endocarditis, and respiratory tract infection [4,5]. Several predisposing factors, including CF, chronic granulomatous diseases, indwelling intravascular catheters, assisted ventilation, and intravenous drug abuse increase the risk of infection with B. cepacia [1,6]. Contaminated fluids, such as tap water and nebulizer, irrigation, and dialysis fluids, have also been reported as sources of B. cepacia infection [1,7,8]. Vertebral osteomyelitis caused by B. cepacia is described rarely, with only three cases, consisting of two cases of cervical and one case of lumbar osteomyelitis, reported in the literature [3,6,8]. The diagnosis of B. cepacia infection in these three cases was confirmed by CT-guided biopsy or open surgery. All of the patients recovered gradually after the prescription of suitable antibiotics, possibly aided by decompressive surgery. The sources of the patients’ infections were probably intravenous drug abuse, previous rhinoplasty with contaminated fluid, and an unnoticed external wound that occurred either during a fall on an icy road or from intramuscular stimulation therapy. Antimicrobial resistance of B. cepacia has been considered a great challenge in treating infection caused by the organism [1]. To the best of our knowledge, B. cepacia infection involving the thoracic spine in