A 27-year-old female with a maximum body temperature of 40.4 C developed low back pain and percussive pain in the renal area about 3 weeks ago. Cotrimoxazole was sensitive to bovine Salmonella enteritis in blood cultures obtained at Beijing Wangjing Hospital (Beijing, China). A combination of antibiotics etimicin sulfate (300mg po qd), cefoxitin (2g po q12h) and cotrimoxazole (4g po qd) was administered. In spite of 3 days of treatment, her symptoms did not improve, so she sought further treatment at our hospital. Previously, the patient had been healthy and did not have any significant medical or surgical history. In addition to eating burgers from unknown vendors before fever, she had no history of epidemic areas, livestock, contact with cattle, sheep, or habit of consuming unpasteurized milk, tuberculosis, smoking, intravenous drug use, or any other HIV infection factors.
At admission, the body temperature was 38.4 C. During the physical examination, there were palpable pains in the spinous processes of the lumbar 4 and 5 vertebrae, lumbar forced positions, lumbar back pain, and limited lumbar flexion. Neither inguinal nor axillary lymph nodes were found, nor was there any evidence of hepatosplenomegaly. Laboratory tests were as follows: hemoglobin (Hb) 96 g/L, red blood cell count (RBC) 2.84x1012/L, serum ferritin 12mug/L, mean corpuscular volume (MCV) was 74.6 fL, mean corpuscular hemoglobin content (MCH) was 23.8 pg, and mean corpuscular hemoglobin concentration (MCHC) was 302g/L, white blood cell (WBC) 8.05x109/L accompanied by neutrophil elevation, platelet 344x109/L, erythrocyte sedimentation rate (ESR) 117mm/h, C-reactive protein (CRP) 75.7mg/L, albumin 34.3g/L, fasting blood glucose 5.6 mmol/L, HIV antibody negative, complement C3 1290mg/L, complement C4 330 mg/L, IgM 1.04 mg/L, IgG 9.66 mg/L, IgA 1.09 mg/L. In the absence of tuberculosis antibodies, the RBPT and acid-fast staining of the sputum smear were also negative, and the chest X-ray was normal. The blood culture was also free of bacteria and fungi after 5 days.
The L4/5 vertebral space was narrowed on the preoperative X-ray (Figure 1A and B). Preoperative CT showed the intervertebral disc of L4/5 and adjacent vertebral body were heavily damaged with dense pores (Figure 1C and D). Preoperative sagittal MRI showed vertebral body and intervertebral disc lesions with low signal on T1-weighted imaging (T1WI), high signal on T2-weighted imaging (T2WI), and high signal on fat-suppressed T2-weighted imaging (FS-T2WI), which was significantly enhanced after enhancement (Figure 1E-H). Coronal and transverse MRI showed vertebral body damage of L4 and L5 complicated by intervertebral disc damage of L4/5 (Figure 1I-L). 
The patient's symptoms did not improve after diagnostic anti-tuberculosis treatment at the Department of Infectious Diseases of our hospital. As a result, he was transferred to Department of Orthopedics for surgical treatment. Preliminary diagnosis is suppurative spondylitis, although brucellosis spondylitis and spinal tuberculosis cannot be ruled out. Following general anesthesia, lumbar posterior lesion removal, decompression, internal fixation, cage implantation, and bone graft fusion were performed (Figure 2A-D). Real-time PCR of the nucleus pulposus samples showed that there was B. melitensis (Figure 3).  
Salmonella enteritis was detected in intraoperative pus secretions 7 days after surgery, and the pathological Giemsa staining of intraoperative tissues (nucleus pulposus, endplate cartilage) showed Brucella contamination (Figure 4). Due to the long-term use of antibiotics, a stool smear revealed possible yeast growth. The patient was finally diagnosed with mixed spinal infection of Salmonella enteritis and B. melitensis. Afterwards, she was prescribed levofloxacin, rifampicin, and doxycycline. Antifungal fluconazole was administered orally. Oral ferrous sulfate tablets for the treatment of iron deficiency anemia. Two weeks after treatment, the patient was no longer experiencing fever or sweating, and was able to perform daily activities using a lumbar brace, CRP returned to normal and ESR (39mm/h) was significantly lower than before, Hb 112g/L and RBC 3.84x1012/L, MCV 91.4 fL, MCH 30.2 pg, MCHC 326. A 6-month treatment course of levofloxacin, rifampicin, and doxycycline was continued after the patient was discharged. A follow-up 2 years later revealed normal CRP and ESR, Hb 119 g/L, and RBC 3.95x1012/L; X-ray showed a good position of internal fixation (Figure 5A and B); CT showed well fusion of L4 and L5 vertebral body, suggesting the formation of new bone in L4/5 disc space (Figure 5C-F); MRI demonstrated a good repair of the lesion (Figure 5G-J).