CHRONIC OSTEOMYELITIS: BEWARE OF PRE-REFERRAL CULTURES

Abstract

Materials & MethodsChronic osteomyelitis is a complex and challenging condition the successful treatment of which requires a specialist multidisciplinary approach. Prior to tertiary referral to a specialist Orthoplastic Unit, patients often receive multiple courses of antibiotics, in usually unsuccessful attempts, to eradicate infection. This often results in the development of chronic polymicrobial infection. We reviewed the intra-operative cultures of patients treated in our Orthoplastic unit over a 9-year period from 2012–2021 to determine the spectrum of polymicrobial cultures and the relationship to pre-operative cultures.ResultsWe reviewed the electronic care records and laboratory results of all patients referred to or directly admitted to our unit with a diagnosis of chronic osteomyelitis between 2012–2021. We checked all culture results, antibiotic sensitivities and prescription for treatment. We also checked for any recurrence of infection within 1 year.60 patients were treated over the 9-year period. 9 upper and 51 lower limbs. The most common referral sources were from the surgical specialties of Trauma & Orthopaedics and Plastic Surgery (62%) while an equal amount came from the Emergency Department and other inpatient medical teams, each making up 15%. A small cohort (8%) developed the infection while still being followed up post fixation.Aetiology of Infection were post fracture fixation 41 (68%), spontaneous osteomyelitis 10 (17%), soft tissue infection 4 (7%). The remaining 5 patients (8%) had a combination failed arthroplasty, arthrodesis and chronic infection from ring sequestrum. 58 patients (97%) had positive cultures with 26 being polymicrobial. 12 cultures were gram negative (G-ve), 11 G+ve 12, 4 anaerobic and 1 Fungal. In 24 patients (40%) the pre-operative cultures and antibiotic sensitivities did not correspond to the intra-operative cultures and sensitivities. 55 patients (92%) required dual or triple therapy with 8% requiring further debridement and extended therapy. 2 (3%) patients had failed treatment requiring amputation.ConclusionsChronic osteomyelitis is a complex and challenging condition the successful treatment of which requires early referral to a specialist Orthoplastic unit. Less than half of organisms cultured pre-operatively reflect the causative organisms cultured intra-operatively with 52% of these infections being polymicrobial.After initial treatment, 8% of patients will require a further combination of extended antibiotic therapy and surgery to eradicate infection.