Department of Rheumatology, Derbyshire Royal Infirmary, Derby and 1 Department of Rheumatology, Queen Alexandria Hospital, Portsmouth, UK
Correspondence to: C. Deighton. E-mail: chris.deighton{at}derbyhospitals.nhs.uk
We thank Dr Fernández-Castro and her colleagues for their interest in the updated British Society for Rheumatology (BSR) guidelines and their case report. Sepsis in a knee arthroplasty is devastating for the patient and results in death in 5% of cases [1]. Even in patients who have the infected arthroplasty replaced (which did not occur in the patient that Dr Fernández-Castro and her colleagues report), reinfection rates have been reported to be 10% after 3 yr and 26% after 10 yr [2]. Organisms that are adherent to a prosthetic joint multiply and elaborate a glycocalyx wall known as a biofilm [3]. Diffusion of antimicrobial agents through biofilms is slow and limited, and organisms may be highly resistant to antibiotics [4]. This explains why patients often relapse days or months after antibiotics are stopped following clinical remission in treating a septic arthroplasty, and why septic prostheses often have to be removed. It also explains our caution in suggesting that anti-TNF drugs should not be used in a patient in whom a previously treated septic arthroplasty remains in situ.
In the case report of Fernandez-Castro et al., their patient had 3 weeks of intravenous antibiotics, extensive surgical debridement and 6 months of oral antibiotics. This approach appears to have eradicated the infection. Their patient had aggressive RA and on the basis of informed consent accepted anti-TNF therapy, from which she has benefited greatly. They have gone against the advice given in the updated BSR guidelines [5].
In updating the guidelines, we started with the original 2001 guidelines [6]. We performed detailed literature searches and contacted the three drug companies that produce the anti-TNF drugs. We found no literature to confirm or refute the statement that patients should not receive anti-TNF therapy with a history of a septic prosthetic joint within the last 12 months, or indefinitely if the joint remains in situ. Furthermore, correspondence from Schering-Plough suggested that they had no evidence to confirm or refute these statements (Elaine Cannon, Medical Information Manager, Schering-Plough; letter dated 11 March 2004). Consequently the only modification that we made to the updated guidelines was to add the statement based on opinion, but no good evidence in parentheses.
Perhaps if we hear of more anecdotes such as the case reported here, we, or our successors, will be including these in the next update of the BSR guidelines. However, we feel that it is unlikely that it would ever be practical or ethical to submit patients to a large trial to determine if anti-TNF drugs are safe in patients with a septic arthroplasty treated without removal. Consequently, if there ever is any relaxation of this aspect of the guidelines, we anticipate that it would contain phrases such as extreme caution and with the patient fully aware of the risks.
The authors have declared no conflicts of interest.
References
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