Propionibacteria are organisms of low virulence, although they do cause deep periprosthetic infections. The aim of this study was to show that Propionibacteria do not always cause a significant rise in ESR and CRP.

Between May 2001 and May 2004, we identified 77 patients with prosthetic joint replacements colonised with Propionibacteria, 47 males and 30 females. There were 47 hip joint replacements, 27 knee joint replacements, 2 endoprosthetic replacements of the femur and 1 shoulder joint replacement. We retrieved successfully the medical records of 66 patients in order to identify the number of patients treated for an infected prosthetic joint arthroplasty. The pre-operative values of ESR and CRP were recorded. For the purposes of this study, an ESR rate of 30mm/hr or higher and a CRP level of 10mg/lt or higher were considered to be suggestive of infection and were deemed a positive result.

All of the 77 patients had both ESR and CRP measured pre-operatively. In only 16 (21%) both ESR and CRP were higher than 30mm/hr and 10mg/l respectively. In 33 patients (43%) with prosthetic joint replacements colonised with Propionibacteria, the pre-operative values of ESR and CRP were normal. 23 patients were treated for an infected prosthetic joint arthroplasty. In 7 (30%) of those patients both ESR and CRP were normal.

This suggests that normal pre-operative values of ESR and CRP in suspected failed prosthetic joint replacements might not exclude infection, if the causative organism is of low virulence such as Propionibacteria.