Microorganisms responsible for periprosthetic knee infections in England and Wales

This study aimed to delineate epidemiology of infecting microorganism genus in first-time revision knee arthroplasty for indication of periprosthetic joint infection in England and Wales using linked registry data.

From the National Joint Registry database for England and Wales, a consecutive series of primary knee arthroplasties performed between April 2003 and January 2014 that went on to have a revision for periprosthetic infection were identified (n = 2810). Each case was then linked to microbiology data held by Public Health England in order to identify infecting microorganism at time of revision surgery established from intra-operative cultures. Following data linkage, 403 culture results at time of revision surgery were identified in a group of 331 patients. The demographic characteristics of five microorganism groups were compared: pure staphylococcus (single genus), pure streptococcus (single genus), other gram-positive infections (single genus), gram-negative infections (single genus) and mixed genus infections.

Staphylococcus species was the most common organism genus isolated after revision of a primary implant for infection and present in 72 % of cases overall (71.3 % of patients with a single-genus infection and 76.8 % of patients with mixed genus infection). A pure staphylococcal infection was present in 59 % of all cases. A single-genus infection was responsible for infection in 83.1 % of cases, and mixed genera were responsible in 16.9 % of cases. A significant difference was observed for mean age at primary procedure in the cohort of patients where there was an isolated pure streptococcal infection (73.2 years) when compared to gram-negative infections (65.0 years). No other significant differences were observed between microorganism groups in terms of BMI, gender, ASA grade, indication for primary procedure and primary implant characteristics.

IV.