Abstract
Implants are highly susceptible to infection [1]. The infection rate is 0.5–2% after hip or knee arthroplasty [2]. Periprosthetic joint infections are hard to eradicate. Until recently, two-stage exchange or life-long antibiotic suppression therapy has been the rule. However, novel treatment concepts evolved. Whereas no controlled trials on the surgical management of prosthetic-joint associated infection are available, much is known about the optimal antimicrobial therapy. Modern treatment concepts are based on animal studies, in vitro data, observational studies and one single controlled trial comparing two different antimicrobial regimens in patients with orthopaedic device-associated infections [2]. The tissue-cage guinea pig model is especially suitable to analyse the role of antibiotics in device-related infections [3]. In this model, different aspects of implant-associated infections have been studied, namely
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host-defense mechanisms around implants [1],
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risk of hematogeneous infection of extravascular devices [4],
Taken together, these experiments showed that an agent acting on slow-growing and adhering microorganism is needed to eradicate device-associated infection. This requirement is only fulfilled by rifamycins in staphylococcal infection and by fluoroquinolones in infections caused by gram-negative bacilli [5–12]. We could show that even new drugs against methicillin-resistant staphylococci (MRSA), such as linezolid and daptomycin, were not able to eradicate experimental foreign-body infections, when used as single agents. In contrast, in combination with rifampin linezolid cured 60%, and daptomycin 67% of the implant-associated MRSA-infections [9,10]. Based on these in vitro and animal data, observational studies were performed in patients with staphylococcal infections associated to orthopedic devices. We developed an algorithm allowing to choose the optimal therapeutic option for each patient [2]. This algorithm has been validated in cohort studies [13,14]. Finally, in a randomized double-blind controlled trial, the benefit of a rifampin-quinolone combination as compared to quinolone monotherapy has been proven in patients with acute orthopedic implant associated staphylococcal infection undergoing debridement with retention [15].
In conclusion, the favorable role of rifampin has been proven in vitro, in animals and in human studies. Also the newest antistaphylococcal agents must be given in combination with rifampin in order to eliminate infection without removal of the device.
Correspondence should be addressed to Vienna Medical Academy, Alser Strasse 4, A-1090 Vienna, Austria. Phone: +43 1 4051383 0, Fax: +43 1 4078274, Email: ebjis2009@medacad.org
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