What Are the Clinical Characteristics and Outcomes of Brucellar Spondylitis in a Nonendemic Region of Southern China?

BACKGROUND: Brucellosis, historically endemic to northern China, has recently shown a southward spread into previously nonendemic regions. Although brucellar spondylitis represents one of the most disabling complications of the disease, its clinical and epidemiologic characteristics in these emerging southern regions remain poorly defined, warranting further investigation. QUESTIONS/PURPOSES: Among patients diagnosed with brucellar spondylitis from nonendemic regions of southern China, we asked: (1) What are the predominant clinical and laboratory findings? (2) For focal lesion aspiration cultures and blood cultures, what proportion of patients had positive cultures and what factors were associated with having positive cultures? (3) What are the characteristic imaging findings? (4) At a minimum 1-year follow-up, what were the proportions of patients with mild sequelae (exertional pain without functional impairment), moderate sequelae (neurologic deficits or work interference), treatment failure, and infection recurrence? METHODS: Between January 2015 and April 2025, we treated 47 patients with brucellar spondylitis at a tertiary medical center in a nonendemic region of southern China. Two patients were excluded because of incomplete clinical records, leaving 45 patients for the baseline analyses. An additional seven patients were excluded from the evaluation of clinical outcomes and sequelae: three because follow-up after completion of therapy was shorter than 1 year and four because they were lost to follow-up after completion of therapy before reaching the minimum 1-year follow-up threshold; this left 38 patients for outcome evaluation. The baseline cohort had a mean ± SD age of 55 ± 11 years; 49% (22 of 45) were women, 58% (26 of 45) lived in rural areas, and 38% (16 of 42) had high-risk occupations. Diagnosis required compatible imaging findings on CT or MRI (including vertebral destruction, disc involvement, or localized abscess formation) together with laboratory confirmation (positive blood culture or focal lesion aspiration culture for Brucella or a standard agglutination test titer of at least 1:100). Demographic, epidemiologic, clinical, laboratory, microbiologic, and imaging data were extracted from electronic medical records. CT and MRI were used to assess vertebral destruction, disc involvement, and abscess formation. All 45 patients received doxycycline-based combination antimicrobial therapy; 76% (34 of 45) were treated nonoperatively with antibiotics and external bracing, whereas 24% (11 of 45) underwent surgery. Clinical outcomes assessed at a minimum of 1 year included recovery, treatment failure, recurrence, and sequelae; recovery was defined as no clinical evidence of ongoing infection at final follow-up. Categorical and continuous variables were compared using the Fisher exact test and independent-samples t-test, respectively, with Bonferroni correction for multiple comparisons. RESULTS: The most common clinical manifestations were low back pain (82% 37 of 45) and fever (58% 26 of 45). In addition, 42% (19 of 45) of patients presented with localized neck or back pain, sometimes with radicular symptoms, but without prominent systemic manifestations; inflammatory markers generally were elevated despite largely normal white blood cell counts. Brucella species were isolated more often from focal lesion aspiration cultures than from blood cultures (62% 21 of 34 versus 48% 12 of 25). Prior antibiotic exposure was less common among patients with positive blood cultures than among those with negative blood cultures (25% 3 of 12 versus 77% 10 of 13, OR 0.1 95% confidence interval (CI) 0.02 to 0.63; p = 0.02), whereas positive focal lesion aspiration cultures were associated with higher C-reactive protein levels (56 ± 29 mg/L versus 30 ± 26 mg/L, mean difference 26 95% CI 6.26 to 46.20; p = 0.01) and lower albumin levels (30 ± 5 g/L versus 36 ± 4 g/L, mean difference -6 95% CI -8.80 to -2.34; p = 0.001). Because only the association between lower albumin level and positive focal lesion aspiration culture met the Bonferroni-adjusted threshold, the associations with prior antibiotic exposure and C-reactive protein level should be interpreted as exploratory. Imaging showed vertebral destruction with sclerosis on CT in 89% (40 of 45) of patients, whereas all patients evaluated with MRI (100% 43 of 43) had abnormal vertebral signal, often with paravertebral abscesses (30% 13 of 43) or epidural abscesses (44% 19 of 43). The lumbar spine (42% 19 of 45) and lumbosacral junction (33% 15 of 45) were the most commonly involved regions, and 64% (29 of 45) of patients had lesions confined to two adjacent vertebrae. At a minimum 1-year follow-up, 95% (36 of 38) of patients recovered, 5% (2 of 38) experienced treatment failure, and no patient had recurrence; mild and moderate sequelae were observed in 32% (12 of 38) and 11% (4 of 38) of patients, respectively. CONCLUSION: In nonendemic regions, clinicians may wish to consider brucellar spondylitis earlier in patients with unexplained back pain, elevated inflammatory markers, and a relatively normal white blood cell count, even when systemic symptoms are limited. Early serologic screening and, whenever feasible, microbiologic sampling before empirical antimicrobial therapy may help support the diagnosis. Because outcome analyses were restricted to patients who completed at least 1 year of follow-up, the reported outcomes may be overly favorable. Future multicenter prospective studies are needed to better define factors associated with culture positivity and early predictors of clinical outcomes and sequelae. LEVEL OF EVIDENCE: Level IV, therapeutic study.