Empirical Antibacterial Therapy for Culture-Negative Pyogenic Spondylodiscitis: Functional and Radiological Outcomes and the Role of Tissue Diagnosis

Abstract

OBJECTIVES

This study aimed to determine the efficacy of empirical antibacterial treatment of culture-negative pyogenic spondylodiscitis in terms of functional and radiological outcomes, with secondary assessment of pain, inflammatory response, treatment failure, recurrence, and requirement for surgery.

METHODOLOGY

A prospective observational cohort design was used at the Department of Orthopaedics and Spine Surgery, Hayatabad Medical Complex, Peshawar. Adults with clinical, biochemical, and magnetic resonance imaging findings compatible with native pyogenic spondylodiscitis, negative blood cultures, and no immediate indication for surgery were included. Patients with suspected tuberculosis, brucellosis, postoperative infection, malignancy, hemodynamic instability, or progressive neurological compromise were excluded. Empirical therapy was selected to cover staphylococci, streptococci, and aerobic Gram-negative bacilli. Functional status was measured using the Oswestry Disability Index (ODI), pain with the Visual Analogue Scale (VAS), and inflammatory response using C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). Assessments were performed at baseline, 6 weeks, 3 months, and 6 months. Two readers independently classified the six-month MRI. Longitudinal outcomes were analysed using linear mixed-effects models.

RESULTS
Sixty-four patients entered the empirical-treatment cohort, and 61 completed 6-month follow-up. Mean age was 50.3 ± 12.0 years, and 39 patients (60.9%) were male. Mean ODI decreased from 62.7 ± 9.7 at baseline to 25.2 ± 13.4 at 6 months; the adjusted mean reduction was 37.38 points (95% CI 35.46–39.29; p<0.001). Mean VAS decreased from 7.62 ± 0.62 to 2.23 ± 1.20, corresponding to an adjusted reduction of 5.39 points (95% CI 5.17–5.61; p<0.001). Median CRP declined from 70.4 mg/L to 5.7 mg/L, while mean ESR decreased from 75.8 ± 16.2 to 26.0 ± 17.2 mm/hour. Favorable MRI response was observed in 54/61 patients (88.5%; 95% CI 78.2–94.3), and overall treatment success was achieved in 56/61 (91.8%; 95% CI 82.2–96.4).

CONCLUSION

A structured antibacterial pathway improved patient outcome, supporting a non-biopsy approach when diagnosis is clear, blood cultures are negative, other serious conditions are excluded, and multidisciplinary monitoring is present. However, tissue diagnosis remains crucial for diagnostic uncertainty or empirical treatment failure.