We read with interest the Clinical Picture by Arvind von Keudell and colleagues
on periprosthetic joint infection due to Mycobacterium tuberculosis. We thank the authors for raising an important differential diagnosis for culture-negative periprosthetic joint infection, particularly among patients from a country in which tuberculosis is highly endemic, and in patients on immunomodulatory drug therapy. The patient described in this case completed 12 months of antituberculosis therapy and has since continued rifampicin and isoniazid treatment, with a plan for long-term suppressive therapy in the setting of retained prosthesis.
No consensus has been reached on the most appropriate strategy for management of M tuberculosis periprosthetic joint infection. Because infection due to M tuberculosis is rare, treatment strategies cannot be compared in a clinical trial. Nevertheless, some inferences can be made from existing knowledge of the pathogenesis of periprosthetic joint infection, the biology of M tuberculosis, and from clinical experience including published case reports.
The ability of many bacteria to form biofilm on prosthetic material underpins current understanding and management of orthopaedic device-related infections, including periprosthetic joint infection. Standard treatment of such infection includes surgical debridement with or without exchange of the prosthesis or its modular components to reduce the bio-burden, combined with a defined course of antibiotics to eradicate remaining biofilm. However, the applicability of this approach for tuberculous periprosthetic joint infection is uncertain because of differences in M tuberculosis biofilm formation.
Ha and colleagues
compared the adherence and the biofilm formation of Staphylococcus epidermidis with those of M tuberculosis on four types of metal segments. By contrast with S epidermidis, M tuberculosis rarely adhered to metal surfaces and showed only scant biofilm formation. Similar results were reported by Chen and colleagues,
who compared Staphylococcus aureus and M tuberculosis in vitro and in vivo. These data agree with our clinical experience and that of others,
confirming that orthopaedic device-related infections due to drug sensitive M tuberculosis, like other tuberculous musculoskeletal infections,
usually respond well to standard tuberculosis treatment regimens.
In our institutions, surgical treatment of orthopaedic device-related infections is not altered when M tuberculosis is isolated. It is focused on the preservation of bone and joint function, similar to cases without the presence of an infection. Anti-tuberculosis therapy is administered no longer than it is for other tuberculous musculoskeletal infections, irrespective of surgical treatment.
We declare no competing interests.
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