With good infection prevention and control practice, many HCAIs can be prevented. This has been demonstrated by the significant reductions in MRSA bloodstream infection in English NHS hospitals between 2005 and 2018 (PHE [98], [99]) and the dramatic fall in the number of cases of C. difficile infection in England (PHE [98], [100]). These reductions were achieved via the systematic application and monitoring of established practices for the prevention and control of infection, including diligent hand hygiene and correct aseptic technique.

The use of effective infection prevention practices, including hand hygiene, environmental cleaning and care of invasive devices, leads to less cross‐transmission, less infection, and less need for antimicrobials and other remedial treatments. It is therefore safer for patients and more cost‐effective, and it contributes to reducing the burden of antimicrobial resistance.

Infection prevention and control underpins the clinical practices of all disciplines of healthcare and is fundamental to patient safety. As in other disciplines, robust evidence should underpin and improve practice and be used to ensure patients are receiving optimal care. However, it is not always possible to carry out robust randomized controlled trials (RCTs) to evidence all interventions and in some cases it is very difficult to ascertain which of several interventions implemented concurrently has made a difference. For instance, in early evidence on the importance of hand hygiene, a paper describing a S. aureus outbreak in a neonatal unit in the 1960s (Mortimer et al. [81]) demonstrated that babies who were cared for by nurses who were instructed not to wash their hands after coming into contact with a baby who was colonized with S. aureus were more likely to acquire the organism than infants cared for by nurses who used the antiseptic hexachlorophene to clean their hands between contact with each baby. This controlled study provided strong evidence that hand washing with an antiseptic agent between patient contact reduces transmission of healthcare‐associated pathogens; however, it has never been repeated due to the obvious ethical drawbacks. Hand hygiene must be accepted as good practice on the basis of the results of a multitude of non‐RCT studies (Pittet et al. [101]) and experience.

The published studies relating to infection prevention are mostly a mixture of RCTs, cohort studies, case studies, time series intervention analyses, surveillance and feedback, observation and an element of common sense. In many cases, a change may be one of several elements tried at the same time and much of the early evidence was derived from outbreak studies, in which a number of interventions were implemented simultaneously. This ‘multimodal’ type of study can lead to a situation where it can be difficult to pinpoint which individual measures have made the difference or have been the most beneficial.

One of the most favoured means of presenting best practice is in the form of ‘care bundles’. It can even be argued that a set of measures implemented during an outbreak comprises an ‘outbreak bundle’. A care bundle is a group of evidence‐based interventions that have been put together to be practised consistently with the intention that if all the elements are undertaken together, a particular outcome will occur – or, in the case of infection prevention, will not occur. The bundle normally consists of around five elements, each of which have robust evidence indicating that, if they are implemented reliably, for every patient, on every occasion, they will result in the most benefit of all possible interventions (Rochon et al. [105]).

One of the earliest and most influential bundles was presented in a paper by Pronovost et al. ([102]). It described the consistent application of an evidence‐based bundle of interventions that demonstrated a sustained reduction in catheter‐related bloodstream infection rates across the whole state of Michigan.

In the UK, in 2005 the Department of Health issued Saving Lives, which is a package of ‘high impact interventions’. This bundle was put together to reduce infection in key target areas including peripheral vascular devices, central vascular access devices, urinary catheters, surgical wound infection, ventilator‐associated pneumonia and nasogastric feeding. The tools were reviewed and reissued by the Infection Prevention Society in 2017. The suite of tools covers: