A 40-year-old male farmer without any underlying condition was admitted to the hospital because of fever, night sweats, and pain in the lower back. The patient had reportedly been well until 3 weeks earlier, when back pain developed. He reported no associated trauma or injury, and no treatment was administered. On the 10th day of illness, he began to have fever with a temperature as high as 38.3 C, along with night sweats, fatigue, and weakness. He took antipyretics, but the fever and back pain persisted. The patient was sent to this hospital for further evaluation. The patient had occupational exposure to livestock. He was married and lived with his wife and children, who were well. There was no history of tuberculosis (TB), recent travel, transfusions, alcohol consumption, smoking, or intravenous drug use. The patient took no medications and had no history of drug allergy. There was no family history of disease.
Upon admission to the hospital, his core body temperature was 39 C, and he had severe pain in the L4-L5 area. Other vital signs and the remainder of the physical examination were normal. The erythrocyte sedimentation rate (ESR) was 70 mm/h. The levels of C-reactive protein (CRP) and interleukin-6 (IL-6) were slightly elevated to 28.93 mg/L and 10.88 pg/ml, respectively ( Figure 1A ). A human immunodeficiency virus (HIV) test was negative, and other blood parameters, including routine blood parameters, liver enzyme concentrations, procalcitonin and creatinine levels, and antinuclear antibody concentrations, were normal. Blood culture was negative. Magnetic resonance imaging (MRI) showed abnormalities suggesting inflammation in the L4 region ( Figure 1B ). An enzyme-linked immunosorbent assay (ELISA) for the detection of Brucella antibodies was performed on plasma, and the results were positive, with an IgM concentration of 12.88 U/ml and an IgG concentration of 89.15 U/ml. To confirm the diagnosis, vertebral tissue aspiration was performed on the second day after admission. The aspirate was sent for bacterial culture and molecular TB detection. An automated blood culture system was used for bacterial culture. Five days later, the bacterial culture result was positive for Brucella, which is a very small, faintly stained Gram-negative coccobacillus that microscopically looks like "fine sand". Polymerase chain reaction (PCR) was negative for Mycobacterium tuberculosis (MTB) DNA. With a confirmed diagnosis of Brucella-related complicated infection, triple therapy including intravenous ceftriaxone (2.0 g qd) and oral rifampin (0.6 g qd) and doxycycline (0.1 g q12 h) was administered. After 2 weeks of treatment, the patient's body temperature returned to normal. The pain in the lower back was also relieved. However, 1 week later (3 weeks from the beginning of anti-Brucella therapy), the patient's symptoms recurred; he had a moderate to low fever (top temperature up to 38.5 C) accompanied by lower back pain. On physical examination, the pain in the L4-L5 area was significantly worse than before. The results of laboratory re-examination showed a normal white blood cell count (8.11 x 109/L), with 62.1% neutrophils, and a highly elevated ESR (86 mm/h) and CRP level (79.75 mg/L). The level of IL-6 increased to 53.91 pg/ml. Liver enzymes, creatinine levels, and antinuclear antibodies were within normal ranges. The second MRI ( Figure 1C ) scan of the spinal cord showed lesion expansion involving the lower posterior part of L4 and focal abscess formation. Due to the recurrent clinical symptoms and imaging findings, abscess puncture and drainage were performed. Cytology showed inflammatory infiltration (of which 65% were neutrophils) without neoplastic cells. Abscess fluid culture results were negative. Despite drainage for 5 days, the symptoms of fever and lower back pain persisted.
Because the patient had been hospitalized since the beginning of treatment, poor treatment adherence could be excluded. Other infections and drug side effects were also ruled out. Accordingly, brucellosis-associated IRIS was suspected. There is no clinical consensus on the definition of infection-associated IRIS, and there is no treatment standard. With reference to the regimen for TB-IRIS treatment, the triple-agent anti-Brucella regimen was continued, and 200 mg of celecoxib twice a day was initiated. However, the patient's symptoms remained after 1 week of treatment. Anti-inflammatory treatment was changed to 0.5 mg of prednisone per kilogram bodyweight (35 mg). Within 3 days, the patient's body temperature returned to normal, and the back pain significantly improved. Both the ESR and CRP level also gradually returned to within normal ranges. Steroid therapy was tapered over a 2-month period. The triple-agent anti-Brucella therapy was continued for 2 weeks, followed by sequential treatment with oral doxycycline (0.1 g q12 h) and rifampin (0.6 g qd). After the overall 14-week treatment course, the third MRI scan ( Figure 1D ) showed that the lower edge endplate of L4 had been damaged, the paravertebral abscess had disappeared, and the lumbosacral soft tissue edema had significantly improved. At the last follow-up visit 2 months after completing the anti-Brucella therapy, the patient had no complaints, and the physical examination was normal.