A 56-year-old woman suffering from fever and general fatigue visited a neighboring hospital and was examined. During her hospitalization, pyogenic spondylitis complicated by an iliopsoas abscess, due to an infection with Mycobacterium species, was diagnosed. However, the species causing the condition was not identified. An infection with Mycobacterium tuberculosis was suspected, and isoniazid (INH), rifampicin (RFP), pyrazinamide, and ethambutol (EB) were prescribed for 2 months from January 2011. Following the initial treatment, INH and RFP were prescribed for 7 additional months. However, the patient's fever persisted, and the iliopsoas abscess gradually worsened. Therefore, in June 2011, for a period of 2 months, a daily dose of 500 mg levofloxacin (LVFX) was added to the INH and RFP regimen, and the abscess improved. In April 2014, the patient was referred to our hospital for further examination and treatment because of a recurrence of pyogenic spondylitis.
The results of the physical examination were as follows: body temperature, 36.8C; pulse rate, 68 beats per minute; blood pressure, 93/75 mmHg; respiratory rate, 16 breaths per minute; and oxygen saturation, 97% on room air. Respiratory sounds and cardiac and abdominal examination findings were normal. There was a purulent region on the left sinciput (Fig. 1) and her right knee was slightly red, swollen, and painful.
The white blood cell count was 12,100 /muL with 73.4% neutrophils, 14.2% lymphocytes, 4.2% monocytes, 7.7% eosinophils, and 0.5% basophils. The levels of C-reactive protein, alkaline phosphatase, and soluble interleukin-2 receptor were elevated to 18.25 mg/dL (normal range: 0-0.3 mg/dL), 988 U/L (normal range: 110-340 U/L), and 4,459 U/mL (normal range: 127-582 U/mL), respectively. Tests for serum antibodies to T-cell leukemia virus and immunodeficiency virus yielded negative results. An interferon-gamma (IFN-gamma) release assay, QuantiFERON(R)-TB Gold (QFT-G) was indeterminate (M. tuberculosis antigen response: <0.05 IU/mL; negative control: <0.05 IU/mL; mitogen response: <0.05 IU/mL).
Computed tomography (CT) revealed osteolytic changes in the vertebrae and abscesses adjacent to the T3 vertebral body (Fig. 2A). 18-fluorine-fluorodeoxyglucose positron emission tomography/CT (FDG-PET/CT) examination showed multiple lesions with an intense FDG accumulation in the abscesses adjacent to the T3 vertebral body and various bones, such as the skull, sternum, clavicles, ribs, vertebral columns, scapulae, pelvic bones, bilateral humerus, and thigh bones. These findings of osteolytic changes in the bones of the whole body more strongly suggested the presence of metastatic carcinomas and blood diseases, such as malignant lymphoma and multiple myeloma than the existence of bacterial infections.
T2-weighted imaging (WI) and diffusion-WI (DWI) revealed several hyperintense signals in the vertebral bodies, their surroundings, the intervertebral spaces, which was consistent with osteomyelitis and spondylitis (Fig. 3), and in the right thigh bone and tibia (Fig. 4). These hyperintense signals of T2-WI and DWI, in investigated bones more strongly suggested bacterial infections than metastatic carcinomas and blood diseases.
M. scrofulaceum was detected in a sputum culture, the abscesses of the right knee, and the subcutaneous forehead abscess. In vitro, the bacterial isolate was resistant to INH, EB, and para-aminosalicylic acid (PAS), but it was sensitive to streptomycin (SM), RFP, cycloserine (CS), kanamycin (KM), enviomycin (EVM), ethionamide (ETH), and LVFX (Vite Spectrum SR, Kyokuto Pharmaceutical Industrial, Tokyo, Japan). The minimum inhibitory concentrations (MICs) reported for RFP, EB, and SM were 40 mug/mL, 2.5 mug/mL, and 10 mug/mL, respectively (Broth MIC NTM, Kyokuto Pharmaceutical Industrial, Tokyo, Japan). The patient was prescribed a combination antibiotic therapy with RFP, 300 mg daily; EB, 500 mg daily; clarithromycin (CAM), 800 mg daily; and SM, 500 mg 3 times a week, from July to August 2014. After completing the first treatment regime, she was prescribed additional treatment with 3 drugs (RFP, EB, and CAM) from September 2014 to August 2016, which resulted in symptomatic relief and a radiological improvement (Fig. 2B).