Risk factors associated with acute hip prosthetic joint infections and outcome of treatment with a rifampin‐based regimen

Copyright © Taylor & Francis 2008. ISSN 1745–3674. Printed in Sweden – all rights reserved. DOI 10.1080/17453670710015418 Sir—In the management of orthopedic device-associated infections, adherence to a treatment algorithm is crucial for a good prognosis (Giulieri et al. 2004, Zimmerli et al. 2004). In their recent publication, Choong et al. (2007) reported the outcome of a treatment protocol for total hip arthroplastyassociated infections (THIs), including debridement with retention and prolonged rifampin-based therapy. Since the authors refer to our treatment concepts, we would like to call attention to the fact that their retrospective study (Choong et al. 2007) clearly used different criteria to select patients for retention of the implant than were described in our algorithm (Zimmerli et al. 2004). Moreover, the duration of antimicrobial treatment reveals fundamental divergences from our approach. We are concerned that the reader of the Choong article may get the impression that their treatment policy is in agreement with our previously published algorithm (Zimmerli et al. 2004). An important basis of our algorithm in defining the treatment duration is the differentiation between ‘curative’ and ‘suppressive’ antimicrobial therapy. In our concept, this is performed in analogy to anticancer treatment. In patients with THI qualifying for debridement with retention, we suggest a treatment duration of 3 months. In contrast, in patients with purely suppressive therapy, the duration is usually 1–2 years, or even up to life-long. The latter treatment option should be limited to patients in a bad general condition who are unable to undergo further surgery. Since Choong et al. (2007) reported that 11 of 14 patients were treated with antibiotics for a median duration of 20 months (range 12 to indefinite), they obviously used a concept of suppression and not one of cure. Therefore, the characteristics of their patients should be analyzed. Important predictors of success for debridement with retention include (i) a short duration of clinical signs and symptoms, (ii) a stable implant, (iii) good condition of the soft tissue, and (iv) antimicrobial susceptibility of the microorganism (Zimmerli et al. 2004). Compliance with these criteria is important, because it significantly improves the chance of cure (Giulieri et al. 2004, Betsch et al. 2008). The duration of symptoms is important, since several studies have shown a high success rate (82–100%) with debridement and retention, if the duration is 3 weeks (Burger et al. 1991, Widmer et al. 1992, Zimmerli et al. 1998, Tattevin et al. 1999, Meehan et al. 2003, Barberan 2006, Laffer et al. 2006). The time to diagnosis of infection, described by Choong et al. (2007) ranged from 5 to 105 days. Moreover, the treatment protocol was also applied in patients with wound discharge (i.e. sinus tract), which is associated with a high risk of treatment failure (Marculescu et al. 2006). Finally, the authors present 7 of 14 patients who were infected with methicillin-resistant Staphylococcus aureus (MRSA) which should be considered as a difficult-to-treat microorganism (Zimmerli et al. 2004). Indeed, in only 4 of the 7 patients with single or mixed MRSA infection could the prosthesis be successfully retained. Taken together, the statement of Choong et al. (2007) that debridement with retention “may be suitable for patients who are not fit for major revision surgery (and) for those who decline further major surgery” is not based on our treatment concepts. Because Choong et al. (2007) highlight the influence of our work on their treatment concept, we would like to emphasize the mentioned differences. Our curative concept for device retention in patients with THI takes into strict consideration all the above-mentioned predictors of success, thorough debridement and 3-month therapy with an antibiotic that contains activity against surface-adhering microorganisms.