The Microbiological Profiles of Infected Prosthetic Implants with an Emphasis on the Organisms which Form Biofilms

Background: In spite of the decreasing incidence of orthopaedic device related infections to 1 %, nowadays, device-related infections still remain a diagnostic, therapeutic and cost -related problem. Aims and Objective: To record the common causative organisms and the contributing risk factors for orthopaedic device-related infections in a tertiary care teaching hospital. Methods: In a prospective study, fifty patients who underwent orthopaedic device implantation from Jan 2009 -June 2010 were enrolled; among them, 42 patients were complicated with infections. The demography, microbiological data, treatment and the outcome of each patient were recorded. Statistical Analysis: The data was analyzed in terms of frequency and percentage. Results: Of the 50 samples, 42(84%) were culture positive, while 8(16%) were cultures negative. The femur was the most commonly affected bone in both males (median age-37.1 yrs) and females (median age-41.3 yrs). Staphylococcus aureus was the organism which was most commonly isolated and which caused biofilms, followed by non-fermenting, gram negative bacilli and Klebsiella spp. We reported the first case till date in the literature of Candida krusei PJI, to the best of our knowledge. No anaerobes were isolated. Tissue trauma, open fractures, post-operative surgical site infections and Diabetes mellitus were found to be the important risk factors. The biofilm forming organisms were commonly associated with polymicrobial infections and even an aggressive antibiotic therapy was often inadequate to eliminate the infections. A conservative surgical treatment was associated with treatment failures. Implant removal or replacement was required in most of the cases to eradicate the infection. Conclusion: The most common bacteria which were isolated included Staphylococcus aureus, followed by Pseudomonas aeruginosa and Klebsiella. A majority of them are resistant to the commonly used antibiotics, leading to treatment failures which necessitated an implant removal.