Aim

We report on the performance of a simple algorithm using a combination of synovial fluid White blood cell count(WBC), C-reactive protein(CRP) and α-Defensin(AD) tests to aid in the diagnosis of prosthetic joint infections.

We reviewed the current screening protocol for MRSA detection in patients admitted for elective lower limb arthroplasty as we thought it may not be cost effective and there is no evidence base for validity of MRSA screening swabs.

The current institutional screening protocol includes MRSA swabs from nose and groin taken on 2 different occasions; the 1st swab taken at time patient was placed on the waiting list and the 2nd swab taken at the Orthopaedic pre-clerking clinic around 6–8 weeks later.

We found that during the study period, of 1791 patients who underwent MRSA screening swabs, only 16 patients had positive results. Of these, 9 patients had known MRSA (2 in care home) and no data was available in 2 patients. However in 5 patients, there was an initial negative swab which later was found to be positive. The time interval in these ranged from 0.6 to 85 weeks (Conversion rate = 0.3%).

The laboratory cost for these screening swabs was £9,027. Given the low prevalence rate of MRSA and low conversion rate at 6 weeks, there is a role for accepting a single-swab screening protocol. This would also result in significant cost savings of around £ 4,500.

We can therefore conclude that in the indigenous population, it is unlikely a patient will de-novo acquire MRSA in the community unless exposed to independent risk factors. We have adopted the new screening protocol where patients are screened routinely for detection and eradication only once prior to admission unless independent risk factors such as previous MRSA colonisation, hospital admission or if being admitted from residential/care home.

There is however no evidence in literature about the time period of validity of MRSA screening swabs.