Frequency of haematogenous periprosthetic joint infection due to bacteraemia caused by gram-positive cocci

Presence of a prosthetic joint entails a life-long risk of haematogenous periprosthetic joint infection (hPJI) during bacteraemia. For bacteraemia with Staphylococcus aureus the hPJI frequency has been described to be up to 40% and for streptococci up to 20%, with large variation among reported frequencies.

We aimed to investigate the hPJI frequency from bacteraemia with virulent gram-positive cocci in patients with hip and/or knee prosthesis.

A population and register based approach was used. Through cross-matching of blood cultures positive for virulent gram-positive cocci and data from the Swedish Arthroplasty Register, patients with at least one prosthesis in place during bacteraemia were identified. Medical records were reviewed if patients had concordant microbiological cultures in blood and synovial fluid, tissue or bone, to determine if hPJI was present. Absence of concordant cultures was interpreted as absence of hPJI.

Of all 2392 episodes of bacteraemia identified during the study period, 143 (6%) caused at least one hPJI. The highest frequency of hPJI was observed for S. aureus (9.6%) and Streptococcus agalactiae (9.3%). Increasing number of prostheses in place, male sex and lower age were independently associated with hPJI. Bacteraemia with other species than S. aureus or S. agalactiae was associated with a lower hPJI risk.

The observational risk of hPJI from bacteraemia with virulent gram-positive cocci was much lower than in previous reports, especially for S. aureus, with an hPJI frequency of 9.6%.