I’ve written this post in preparation for next week’s Journal Club in partnership with the Healthcare Infection Society themed around their MRSA article collection: “MRSA: the enduring foe”. Having spent a fair bit of time this week looking at post-infection reviews related to MRSA bloodstream infections, I can vouch for how well this particular foe has endured, even in a relatively low prevalence setting!

It’s a while since I’ve read anything on S. aureus – to the point where my fingers automatically type “auris” (thanks for that Candidozyma). So, if you read S. auris below, please forgive me and ignore it!!

Why I chose this article:

• Whilst it’s true the MRSA isn’t the foe that it once was (at least in terms of incidence of serious infection in the UK), it’s still fairly commonplace and can cause serious infections.
• MRSA prevalence in other parts of the world is much higher than in the UK, and akin to the “bad old days” in some parts of the world. I’ve picked some data from France, Greece, and Malta to make the point that some European countries have followed a downward trend, which has not been matched everywhere.
• There is considerable heterogeneity of practice when it comes to MRSA admission screening strategies.

Design and methods:

• The study was undertaken at the Mater Dai Hospital in Malta, a 1,000 bed hospital that basically serves all of the acute care needs for the residents of Malta! I’ve had the privilege of visiting the hospital and it’s wonderful, with incredibly welcoming staff.
• The study aimed to evaluate the impact of introducing universal admission screening (excluding paediatrics and obstetrics) from 2014 onwards in terms of impact on MRSA prevalence/incidence and cost-effectiveness.
• Cost-effectiveness was assessed by balancing the cost of MRSA infections (excluding colonisation) in terms of quality adjusted life years (QALYs) against the cost of the intervention.

Key findings:

• The proportion of MRSA positive screens through targeted screening (2008-2014) was 12.5%, which fell to 5% by 2019 following the introduction of universal screening in 2014.
• The proportion of meticillin-resistance in S. aureus fell from 50% before universal screening to 20% by 2019.
• A statistical model (accounting for possible confounders such as changes in antimicrobial agent and alcohol gel consumption) found that the intervention had a significant impact on both the incidence of MRSA and the proportion of S. aureus resistant to meticllin.
• The cost of the MRSA programme (including people, lab costs, and decolonisation) was 90,000 Euros per annum, which resulted in a cost-per-QALY of 1,058 Euro. We typically use a £30,000 threshold in terms of willingness to pay for a QALY, so the ~1,000 Euro per QALY is way below this. According to these methods, the intervention was very much cost-effective.

Strengths and limitations:

• Remarkably, compliance with the screening programme was 98% – this was because people in the IPC team employees want around and personally swabbed all admissions (this is 1,000 bed hospital – so not a small undertaking to say the least).
• The study was undertaken over a long period of time. The authors make the case that this is a strength because it allowed time for the intervention to slowly turn the tide on MRSA. On the other hand, quite a lot of changes would have happened to healthcare provision over this time frame, which may confound any association.
• The study includes some data around antimicrobial agent and alcohol gel consumption, which didn’t radically change and were unlikely to have influenced the changes in MRSA (the model did control for this).
• The study was uncontrolled, so we don’t know what would have happened if the universal admission screening approach had not been implemented.

Points for discussion:

• You’d expect the % positivity rate of admission screens to decrease when you switch from risk-factor based screening to universal screening, because you’re screening a larger group of lower risk patients (in addition to the higher risk ones). But there was certainly evidence that the intervention did reduce the incidence of MRSA.
• What caused the spectacular reductions in the prevalence of MRSA colonisation and serious infection in the UK? Can we really attribute this to universal admission screening?
• Does universal admission screening make sense in a low prevalence setting?
• What is the most appropriate method for MRSA admission screening (e.g. rapid vs. culture based, which body sites to screen)?
• Is extending the IPC team and employing dedicated staff the best way to achieve high compliance with admission screening programmes?
• MRSA patients were not routinely moved to single rooms and yet control was achieved. Does this argue against single room isolation for patients with known MRSA colonisation?

What this means for IPC:

• Perhaps it time to review your MRSA admission screening approach!

Finally, hope you can join us for Journal Club next Wednesday (register here).