Abstract
Introduction: The evolving pattern of bacterial resistance at septic revision surgery to the common antibiotics used during total hip arthroplasty is described.
Methods: A retrospective review of 72 case notes and microbiology data inclusive of bacterial sensitivity profiles was undertaken between January 2002 and April 2007. Data collected was combined with a previous study to demonstrate bacteriology trends over the last thirty years (327 cases). Antibiotic sensitivities to the two common infectious agents, Staphylococcus aureus and coagulase negative staphylococi were formulated into a hypothetical model combined with Gentamycin sensitivity, a constant factor (the sole antibiotic in bone cement), to assess the efficacy of the combination of antibiotics used in primary arthroplasty.
Results: When compared to previous microbiology data percentage isolates of each bacterium were found to be similar, confirming that the infectious agents at septic revision had remained the same, and were the common contaminants at primary surgery. The results also demonstrated an overall trend of increased resistance of the major organisms to the major classes of antibiotics used. Staphylococcus aureus and coagulase negative staphylococci were routinely tested against nine common antibiotics, inclusive of Gentamycin. Critical findings showed that the regimen used in routine primary surgery covers only 67% of staphylococcus infections (cefuroxine and Gentamycin); combinations that showed increased coverage included clindamycin and Gentamycin, and rifampicin plus Gentamycin, providing in excess of 100% coverage, and Erythromycin and Gentamycin, coverage in excess of 80%.
Discussion: Consequently we can recommend from prospective analysis of common infections at septic revision, that the antibiotic regimen at primary surgery is not sufficient to prevent infection (in isolation). Dynamic variations continuously develop in bacteria; genetic make up is regulated to optimise survival, continuously detrimentally affecting the efficacy of antibiotics against the power of super bugs, indicating a pattern in need of continuous monitoring and review.
Correspondence should be addressed to Mr Peter Howard, Editorial Secretary, BHS, c/o BOA, The Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE, England.
