Clostridioides difficile (C. difficile), methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli) are bacterial infections that commonly occur as a direct result of healthcare interventions (such as medical or surgical treatment), or from being in contact with a healthcare setting. They are the most well-known healthcare-associated infections (HCAIs). HCAIs pose a serious risk to patients, staff and visitors, can incur high costs for the NHS, and can cause significant morbidity to those infected. The emergence of new infections also poses a risk to patients and staff, as highlighted by the transmission of Covid-19 in health and care settings during the pandemic. As a result, infection prevention and control is a key priority for the NHS.
Public Health England defines an acute respiratory infection outbreak as two or more laboratory confirmed cases of Covid-19, influenza or another respiratory pathogen linked to a particular setting. In care homes and hospitals, outbreaks generally peak in winter; in winter 2019-20 there was a maximum of 82 new outbreaks in care homes in week 1 of 2020 (beginning 30 December 2019) and a maximum of 13 new outbreaks in hospitals in week 2 of 2020 (beginning 6 January 2020).
In March 2020, the number of new outbreaks increased dramatically, driven by the Covid-19 pandemic. The number of new outbreaks in care homes increased from 17 in week 10 (beginning 2 March 2020) to 1,010 in week 15 (beginning 6 April 2020). In hospitals there was a peak of 52 new outbreaks in week 14 (beginning 30 March 2020). Outbreaks fell during the summer of 2020, as the number of Covid-19 cases decreased and NHS and care organisations became better equipped to prevent and respond to outbreaks.
However, outbreaks increased again in winter 2020-21 alongside the rise in Covid-19 cases, reaching a maximum of 91 new outbreaks in hospitals in week 49 of 2020 (beginning 30 November). The number of new outbreaks in care homes reached a maximum of 921 in week 1 of 2021 (beginning 4 January), although mortality data indicates that the impact on residents was less severe than during the first wave. Outbreaks decreased again during the spring of 2021, but increased slightly during the summer. In week 37 of 2021 (beginning 13 September), there were 154 new outbreaks in care homes and 17 new outbreaks in hospitals.
It is worth noting that the data presented here does not indicate the number of individuals infected in each outbreak. No data was published between 20 May 2019 and 29 September 2019, resulting in a break in the time series.
In 2007, the levels of healthcare-associated infections, including C. difficile, became a major national concern, in particular following the Healthcare Commission’s investigation into Maidstone and Tunbridge Wells NHS Trust. Action to address these problems was far-reaching and included new legislation as well as focused investment, regulation and performance monitoring against targets. Following this focus in 2007, the total number of C. difficile infections decreased year-on-year to reach a low of 13,362 cases in 2013/14.
In 2014/15 there was a slight increase in C. difficile infections from the previous year, a 4% increase for hospital-onset cases and an 8% increase for community-onset cases. Since then, the number of C. difficile infections has fluctuated. In 2020/21, there were 4,254 hospital-onset cases and 8,249 community-onset cases.
In 2007, the level of healthcare-associated MRSA infections also became a major national concern, similar to C. difficile. The reduction in the number of MRSA cases has followed a broadly similar trajectory to that of C. difficile. Between 2007/08 and 2014/15, there was an 82% reduction in total cases (a 90% reduction in hospital-onset cases and a 70% reduction in community-onset cases). Despite this reduction, the number of MRSA cases increased slightly in 2015/16 and has fluctuated since then. In 2020/21, there was an 8% increase in hospital-onset cases and a 25% decrease in community-onset cases on the previous year.
Enhanced surveillance of E. coli bacteria has been mandatory for NHS acute trusts since June 2011. Following a worrying increase in E.coli infections, the NHS Patient Safety Strategy includes a goal to decrease healthcare-associated Gram-negative bloodstream infections by 25% by 2021 and halve them by 2024. E. coli represents 55% of all Gram-negative bloodstream infections, and reducing the number of E. coli infections is an important safety issue. Preventing bloodstream infections would also reduce the need to prescribe antimicrobials, which is a key way of reducing the rise in antibiotic resistance.
Between 2012/13 and 2019/20, the total number of E. coli infections increased by 34%, from 32,309 to 43,294. The number of community-onset cases increased by 44%, but the number of hospital-onset cases only increased by 4%. The smaller increase is likely to reflect higher rates of blood culture testing as awareness of sepsis risk has increased. In 2020/21, the total number of E. coli infections decreased by 15%.
About this data
National flu and Covid-19 surveillance reports
Acute respiratory infection incidents are based on situations reported to Public Health England Health Protection Teams. A confirmed outbreak of acute respiratory infections is defined as two or more laboratory confirmed cases (Covid-19, influenza or other respiratory pathogens) linked to a particular setting.
C. difficile, MRSA and E. coli data
The bacterial infections are deemed to be hospital-onset if the following rules are met:
- the location where the specimen was taken is given as 'acute trust' or is not known;
- the patient was either an 'In-patient', 'Day-patient', in 'Emergency assessment' or the patient type is not known;
- the patient's specimen date is on, or after, the third day of the admission (for MRSA and E. coli) or the fourth day of the admission (for C. difficile), where the day of admission is day one.
If the above rules are not met, then cases are deemed to be community-onset.