Study of the role of bacterial infection as the predominant cause for back pain

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Introduction Degenerate intervertebral disc can cause back pain or neck pain and /or arm or leg pain (if compressing on the nerve root). Correlation between MRI scan findings of degenerate disc and back pain is poor. It is not uncommon to find poor correlation between arm or leg pain symptoms and degree of compression of the nerve root (on MRI scan). Inflammatory mediators have been implicated as the cause for this discrepancy. A few investigators have found infection of disc by low virulent organisms in these degenerate discs and in sciatica in a surprising 45% of cases. The organisms found are skin commensals and there is a high likelihood that these are contaminants. Treating all back pain or sciatica patients with long-term antibiotics is unreasonable and harmful without a strong proof of infection. Unfortunately these studies are underpowered and do not have a stringent contaminant control arm. Aims Primary: To find the rate of true infection in degenerate discs Secondary: To find the risk factors for true infection Proposal research design This is a case control study comparing incidence of true infection of intervertebral disc in degenerate disc disease patients undergoing spine surgery to patients undergoing spine surgery without degenerate disc (trauma/scoliosis/tumour). Methods All patients undergoing discectomy for various indications will be eligible to participate. At the time of surgery, disc removed as a part of the intended procedure (discectomy or fusion) will be sent for culture. A small amount of tissue generally removed as a part of the procedure (fat/muscle/ligamentum) will serve as contamination control and will also be sent for culture. Prolonged cultures will be performed to identify low virulent organisms. Data collected will include demographic data (age, sex, pre-existing health problems, diabetes, smoking, medications, immunocompromised status, smoking, family history etc), radiological data and type of surgery. If the disc culture is positive and other tissue culture is negative it will be assumed to be infected. But if the other tissue is also positive then it is presumed to be contamination. Two other arms were added to the original study: . 1. Contamination (Sham) arm: paraspinal cultures were also undertaken in patients undergoing spinal surgery without discectomy. We aim to obtain contamination rate from this cohort. 2. Histopathological arm: A subset of patients also underwent histopatholgical evaluation to review inflammatory changes in the disc samples. this was planned to augment the notion of disc infection in degenerated discs