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In the early 2000s, bacteria that are resistant to antibiotics were widespread in UK hospitals and a strain of methicillin-resistant Staphylococcus aureus (MRSA) posed a major threat to public health. This led to nationwide infection control programmes in the mid-2000s, with a rapid decline in rates in NHS hospitals over the following decade.

This study looked at data on bloodstream infections in more than one million patients treated in UK intensive care units (ICUs). Researchers assessed the impact of infection control programmes in this vulnerable population.

There was a 97% reduction in MRSA bloodstream infections in ICU patients between 2007 and 2016, and a 78% decrease in bloodstream infections overall, demonstrating the success of the national drive to control infection. However, the decrease in bloodstream infections has levelled off since 2012. This indicates that any further reductions may require a new approach.

These data provide an unprecedented insight into the impact of the UK’s infection control campaign on infections in ICU patients across the whole population. There are important lessons for other healthcare systems where MRSA and other bloodstream infections remain a problem.

What’s the issue?

MRSA is resistant to several types of antibiotics, making it harder to treat successfully.  Some people carry this so-called ‘superbug’ on their skin, and it becomes a problem only if it invades their skin or deeper tissues. But it can kill. Between one and two in ten patients with an MRSA infection in their bloodstream will die.

In the early 2000s, MRSA was widely present in UK hospitals and there was intense political, media and clinical pressure to reduce infection rates. The reporting of MRSA infections was made mandatory for NHS hospitals in England in 2001. In 2004, a raft of infection prevention and control initiatives were put in place. They led to multiple changes in clinical practice, including improved hand hygiene and cleaning procedures. The same year, a national target was set, to halve the number of MRSA infections in hospitals in England by 2008.

By 2012, there had been an 86% reduction in MRSA infection rates in NHS hospitals, but the national impact on MRSA infections in ICUs had not yet been documented. These patients tend to be older, sicker, and weaker – which makes them especially susceptible to these infections.

What’s new?

The researchers examined data from all ICUs that participated in a national clinical audit of critical care patients in England, Wales, and Northern Ireland. The Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme (CMP) included 1,189,142 patients admitted to ICU between 2007 and 2016.

At the start of the study, there were 139 participating ICUs, increasing to all 276 general ICUs and most specialist ICUs – making it an almost complete national dataset of the ICU-population.

The researchers used bloodstream infections as an indicator of the burden of serious, life-threatening, potentially preventable infections. The data was adjusted for patient characteristics such as age, sex, and severity of illness.

The study found that, in ICUs between 2007 and 2016:

  • The spread of MRSA decreased by 84% – from 25 to 4 new cases for every 1000 patients
  • MRSA bloodstream infections reduced by 97%
  • Bloodstream infections overall reduced by 78% - from 7 to 2 for every 1000 days spent on ICU.

Why is this important?

This study emphasises the success of the infection control campaigns and measures that were implemented in UK hospitals in the 2000s. It has previously been shown that this led to reductions in MRSA infections in UK hospitals over the following decade. This study shows that there were similar dramatic reductions in all bloodstream infections in ICU patients.

It demonstrates the importance of comprehensive population-level surveillance programmes that can provide robust evidence of the impact of an intervention.

What’s next?

The rate of bloodstream infections in ICUs remained static during the last four years of the study, implying that the maximum benefit from current infection control measures has been achieved. This ongoing dataset can be used to monitor new national infection control strategies – or provide an early warning for how new events, such as the COVID-19 pandemic, might impact on superbug infections in the ICU so that any changes can be tackled quickly.

You may be interested to read

The full paper: Edgeworth JD, and others. Reductions in Methicillin-resistant Staphylococcus aureus, Clostridium difficile Infection and Intensive Care Unit–Acquired Bloodstream Infection Across the United Kingdom Following Implementation of a National Infection Control Campaign. Clin Infect Dis. 2020;70:2530-2540

Information on MRSA, NHS. 2020

Funding: This research was supported by the NIHR Biomedical Research Centre based at Guy’s and St Thomas’ NHS Foundation Trust and King’s College London, the programme of Infection and Immunity and the NIHR Collaboration for Leadership in Applied Health Research and Care South London at King’s College London NHS Foundation Trust.

Conflicts of Interest: The study authors declare no conflicts of interest.

Disclaimer: NIHR Alerts are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that views expressed in NIHR Alerts are those of the author(s) and reviewer(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

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