Public health microbiology: infection prevention and control

1 Introduction

The critical and defining element of all infections and infectious diseases is their capacity to spread. The fact that infection can spread from person to person (patient to patient) by direct contact, or by the hands and clothes of healthcare workers, or by contamination of equipment or the environment, means that there is a public health and infection control aspect to all infections. For every patient who acquires an infection there is a need for specific treatment for that patient, but we also need to address the two infection control issues—from where (or from whom) has the infection come, and how can we minimize the risk of it spreading to others. This is the subject of infection prevention and control.

Among the broad range of infections, those that develop as complications of other illnesses or of the treatment of those illnesses, possibly by cross-infection but also by infection from the patient’s own bacterial flora, are a major concern to health services throughout the world. These are variously known as hospital acquired infections, hospital cross-infections, or more generally now, healthcare-associated infections (HCAIs) to reflect the fact that they occur in patients throughout health and social care settings, not just those in hospital. An increasingly elderly population with a range of chronic medical conditions and the tremendous success of modern medical and surgical practice in increasing life expectancy and treating previously fatal conditions means that health services have to deal with many patients who are highly vulnerable to infection. Invasive clinical procedures are an essential part of most medical care, as are treatment requirements causing significant immunosuppression, both of which are key risks for the patient developing an HCAI.

One of the main responsibilities of all clinicians is that they should, as a priority, not harm their patients through the investigations and treatment they give. Clearly, with modern medical and surgical practice, all risks cannot be eliminated, but the risks must be minimized, in particular the risk of these vulnerable patients acquiring an infection as a direct result of their healthcare. Hence there is a specific focus in all health services on the of HCAI.

2 Healthcare-associated infections—definitions and range

HCAIs encompass a considerable variety of infections of different body sites and systems caused by a wide range of bacteria and some viruses and fungi. The types of infection reflect all the body sites and systems that can be the subject of medical intervention.

2.1 Wound and soft tissue infections

Any wound, accidental or surgical, breaches one of the key barriers to infections—the skin. With accidental wounds, contamination with dirt, soil and environmental bacteria may be inevitable, but with ‘deliberate’ surgical wounds, every effort must be made to minimize the risk of postoperative wound/surgical site infection (SSI; the term reflects the importance of infection at any part of the surgical site, not only the obvious external wound). These SSIs may come from the patient’s own normal body flora (e.g. from the intestinal bacteria after abdominal surgery), from nose or skin carriage of wound pathogens such as Staphylococcus aureus by the patient, or by cross-infection from other patients or staff as a result of a breakdown of aseptic procedures and proper clinical care. Protocols for clinical care of surgical wounds aim to minimize the risk of the cross-infection, and antibiotic prophylaxis combined with careful surgical practice aims to minimize the risk from the patient’s own endogenous bacteria.

Non-surgical soft tissues sites are also prime sources of HCAI, particularly peripheral ulcers (vascular, diabetic, etc.) and pressure sores (decubitus ulcers) where the initial vascular insufficiency and tissue breakdown provides an ideal environment for bacterial infection.

2.2 Bloodstream infections

Potentially the most severe types of HCAI in terms of outcome are bloodstream infections (bacteraemias). The blood and the cardiovascular system should be sterile and the presence of bacteria in the blood is an alarm signal for a patient’s healthcare. Many bacteraemias are part of infectious diseases not linked to healthcare risks (bacterial meningitis, community acquired pneumonia, acute pylonephritis) but others are important complications of healthcare. Almost all hospital treatment in modern medical practice requires invasive procedures with the insertion of various synthetic tubes and prosthetic devices. The insertion of indwelling intravascular catheters and cannulae penetrates the protective layer of the skin and provides a portal of entry for bacteria. Central venous catheters are used increasingly for a range of clinical investigations and treatments and carry a significant risk of infection which starts on the artificial surface of the catheter and then seeds the bloodstream more generally, with the risk of clinical sepsis and infection of cardiovascular structures such as the heart valves (endocarditis) or other metastatic infection sites. Short peripheral intravenous cannulae carry less individual risk of infection, but so many are used in modern clinical practice that they are in fact the source of more HCAI bacteraemias than central catheters. Other local sites of HCAI (wounds, ulcers, urinary tract, respiratory tract) can also lead to bacteraemia.

2.3 Urinary tract infections

The commonest form of HCAI (see below) are urinary tract infections, mostly as a result of indwelling urinary catheters which inevitably become contaminated and colonized with bacteria, then leading to infection of the bladder and the lower urinary tract, then the ureters and potentially the kidneys (pylonephritis). This can be an important cause of bacteraemia.

2.4 Respiratory tract infections

Respiratory infections are some of the most common types of infection in the general community and these can also affect hospital patients, but some clinical conditions and treatments predispose patients to healthcareassociated respiratory tract infections. During the postoperative period surgical patients are particularly vulnerable to pneumonia; they will have undergone endotracheal intubation for their anaesthesia and postoperative discomfort and inactivity may lead to inadequate ventilation of their lungs and inability (or disinclination) to cough, resulting in postoperative pneumonia. This risk is greatly magnified in patients needing intensive care and undergoing prolonged intubation and artificial ventilation. Ventilator-associated pneumonia (VAP) is one of the major challenges to successful intensive care. As well as the local effects of VAP on the respiratory tract, it is also a significant cause of bacteraemia.

2.5 Gastrointestinal tract infections

Infectious diarrhoea is a well-recognized community syndrome. Some of the issues that result in diarrhoea and vomiting in the population at large, such as mass catering leading to food poisoning with Salmonella and Campylobacter spp. also apply in hospitals and other healthcare and social care settings but other gastrointestinal infections cause particular problems in relation to healthcare settings. Norovirus vomiting and diarrhoea spreads so readily in closed communities that it causes numerous and frequent outbreaks in all health and social care settings and is the commonest cause of ward closures in the NHS in England to control the spread of this virus. One bacterial cause of potentially severe, indeed fatal, diarrhoeal disease that is much more specifically an HCAI is Clostridium difficile infection (CDI). This infection generally affects only those whose normal gut bacterial flora has been disturbed by treatment with broad spectrum antibiotics (or some other infection proven or suspected) which enables the Cl. difficile spores to germinate and then the vegetative bacteria to produce their damaging toxins.

3 Microorganisms that cause HCAI

Although some infectious agents causing HCAI are also involved in community acquired infectious diseases (norovirus, Salmonella spp., Staph. aureus), many HCAIs are caused by organisms particularly associated with healthcare. These bacteria are generally characterized by two properties: they tend to be resistant to many antibiotcics and have been selected by pressure of antibiotic usage in healthcare, and they are also generally opportunist pathogens with less capacity to produce illness in otherwise fit and healthy people but able to cause severe and life-threatening infection in those who are vulnerable and most susceptible because of their underlying diseases and/or their treatment. Some, in particular, can be associated with artificial implants and prostheses.

3.1 Staphylococcus aureus, including MRSA

Staph. aureus is inextricably linked with human health and disease. Its natural habitat is the human skin particularly the anterior nares and the warm, moist skin folds of the perineum (and groin) and axilla and at any one time about one third of people are colonized with Staph. aureus, alternatively known as ‘carriers’. The nose is the principle carriage site in most (probably all but not always detectable) carriers with the skin sites also colonized in a smaller number. Staph. aureus has always been the most common cause of wound infections (accidental and surgical) and a leading cause of HCAIs. When penicillin was first used clinically in the early 1940s, almost all Staph. aureus strains were susceptible to it and it was widely used. By the late 1950s, 95% were resistant to penicillin due to natural selection of penicillinase (β-lactamase)producing strains. Meticillin (formerly known as methicillin), and the later oxacillin, cloxacillin and flucloxacillin, was developed to resist breakdown by β-lactamase and restore treatment options. Within a year of introduction, the first meticillin-resistant Staph. aureus (MRSA) strain was described. MRSA were interesting rarities in the 1960s and through the 1970s. In the 1980s, some MRSA strains (now called epidemic strains; EMRSA with sequential numbers) caused isolated and restricted outbreaks of HCAI which were mostly contained by a ‘search and destroy’ approach (i.e. isolate and treat the patient; screen all contacts among patients and staff for carriage; give decolonization treatment to any found to be positive). However, in the early 1990s in the UK, two EMRSA strains, 15 and 16, emerged with greater capacity to spread in healthcare settings and to cause a higher proportion of severe disease. Their spread through the healthcare system was not controlled and these strains became a major HCAI problem and the subject of media publicity, pressure group campaigns, and political concern in the early years of the 21st century. These strains were difficult to treat and caused significant morbidity and mortality. However, it must be remembered that MRSA is not a disease; it is a group of Staph. aureus strains that cause a wide range of HCAIs—wound and soft tissue infections, VAP, catheter-associated UTI, as well as the bacteraemias that have been a major focus for surveillance and preventive measures as being the most severe end of the spectrum of MRSA disease

3.2 Staphylococcus epidermidis (coagulase-negative staphylococci)

Everyone carries Staph. epidermidis, and sometimes other coagulase-negative staphylococci (CNS), on their skin as part of the normal flora. These CNS are often antibiotic resistant (including being meticillin resistant) but have much less pathogenic potential than Staph. aureus for healthy people. However, they are one of the most common causes of HCAI associated with indwelling artificial devices and prosthesis. Despite the emphasis on MRSA bacteraemia, S.epidermidis is the most common cause of intravenous line-associated bacteraemia, but with more low-grade or ‘grumbling ’ clinical presentations and fewer severe and fatal infections than MRSA. It is also the commonest cause of late onset deep infections of implanted prostheses such as hip and knee joints and heart valves. In this respect they cause significant morbidity and treatment often requires removal and replacement of the original implant.

3.3 Gram-negative bacteria

Several distinct groups of Gram-negative bacilli have the capacity to cause opportunist infections in vulnerable patients, particularly those with various forms of immunosuppression. All share a general characteristic of being able to survive in moist environmental conditions and being resistant to a range of antibiotics so that their survival and spread is selected by the widespread use of antibiotics in hospitals and other healthcare settings. This group of opportunist pathogens has long included organisms such as Pseudomonas aeruginosa (or other Pseudomonas species), Acinetobacter spp. and the resistant enterobacterial relatives of Escherichia coliEnterobacter, Serratia and Klebsiella spp. All have caused serious infections in immunocompromised patients, e.g. patients undergoing chemotherapy for a malignant disease in whom Gram-negative bacteraemias have a high incidence, often leading to clinical sepsis and death. Ps. aeruginosa causes similar infections but also has a long association with pulmonary infection in cystic fibrosis patients.

Two further challenges from Gram-negative bacteria are causing concern with the emergence of new antibiotic resistance markers. The ß-lactaen antibiotics (penicillions and cephalosporins) have been mainstays of treatment of E. coli and related Gram-negative bacteria for many years. Strains of E. coli have now emerged that have acquired genes for the production of extended spectrum β-lactamases that break down all β-lactam agents. These ESBL-producing E. coli have become widely established in patients in hospitals and in other health and social care settings. Gut colonization is linked to urinary tract infection, especially when the patients are catheterized, and this can then result in bacteraemias that are very difficult to treat. Carbapenen antibiotics (e.g. imipenem) are important for treatment of these resistant Gram-negative HCAIs, so it is of special concern that some carbapenemase-producing Klebsiella spp. and other Gram-negative species are now being found in some UK and other European hospitals.

3.4 Glycopeptide-resistant enterococci

Enterococci (Enterococcus faecalis and Ent. faecium) have been recognized causes of HCAI in immunocompromised patients, e.g. post-transplant (including bonemarrow recipients) and cancer chemotherapy. These organisms are intrinsically resistant to many antibiotics and the mainstays of treatment where the glycopeptides vancomycin and teicoplanin. There was particular concern in the early 2000s when glycopeptide-resistant strains of Ent. faecium caused small but severe outbreaks in transplant and chemotherapy units. A suggested link to glycopeptide use in agriculture has not been proven, and although such strains still cause some serious infections, they have not become a widespread problem in other patient groups.

3.5 Clostridium difficile

Cl. difficile was discovered to be the major cause of antibiotic-associated diarrhoea and colitis simultaneously by groups in the UK and the USA in 1978. Although the subject of much interest and research amongst anaerobe microbiologists and a few infectious diseases physicians, it did not reach popular notoriety until the middle of the first decade of the 21st century. Cl. difficile is an anaerobic spore-forming organism found in the gut of many species of animal, including humans. With conventional bacteriological methods, about 3% of healthy people are found to carry Cl. difficile in their faeces. However, the figure is much greater in hospitalized patients and in residential nursing and care home residents. Patients with Cl. difficile diarrhoea excrete large numbers of spores into their surrounding environment where they can survive for weeks, months and even years.People with a normal, healthy gut flora can swallow Cl. difficile spores without ill effect, but in patients whose normal intestinal flora is disturbed, especially and most commonly by use of broad-spectrum antibiotics, the normal inhibition of Cl. difficile germination and growth is removed and Cl. difficile grows rapidly. The vegetative Cl. difficile cells attach to the gut mucosa and produce two toxins (A and B) that cause the disease. Toxin A is specifically called an enterotoxin whereas toxin B is a cytotoxin, but they show considerable structural and functional overlap and toxin B in particular can produce severe disease on its own when a strain that is A-negative/B-positive is the cause of the infection. The toxins cause diarrhoea, ranging from mild to profuse and debilitating, and colonic ulceration (which appears as erupting volcanoes on microscopy and biopsy specimens) that can develop into pseudomembranous colitis with, at worst, toxic megacolon and colonic perforation.

The directly attributable mortality in several well-documented outbreaks has been around 10% during the initial stages of infection, but in the cohorts of elderly patients who have had CDI, the overall mortality over a period of 2–3 months can be as high as 40%.

The precipitating factor of antibiotic use and the range of severity of CDI have been recognized since the late 1970s and the infection was well documented in the 1980s in surgical patients from over-use of clindamycin and the cephalosporin antibiotics for surgical prophylaxis (and in immunocompromised groups), but it was not regarded as a priority. In an outbreak amongst elderly patients in hospital in the winter of 1991 in Manchester, there were more than 170 cases with 17 deaths. The patients were on open ‘Nightingale’ wards and most had received antibiotics for chest infections. For the first time, strain typing (by pyrolysis mass spectrometry at that stage) proved that the outbreak was caused by a single strain spread by cross-infection in the hospital setting. A subsequent Department of Health and Public Health Laboratory Service review and report provided guidance and recommendations that remained relevant a decade later but were not generally applied and acted upon with the rigour that was needed. The number of cases reported rose steadily during the 1990s and reached epidemic proportions by the early 2000s when the general increase was compounded by the emergence (in North America, the UK and Europe) of a new strain designated ribotype 027 with increased virulence and specific resistance to fluoroquinolone antibiotics which were being used increasingly in community and hospital practice. The serious impact of this disease meant that health services in the UK and elsewhere had to take specific and vigorous actions to bring down the unacceptably high incidence of CDI which was compromising the delivery of healthcare. Not only were patients suffering from a serious infection that compromised their underlying medical problems, but the management of these patients placed great pressure on hospital services overall and were a serious drain on health service resources.

3.6 Norovirus

Norovirus infections cause very significant disruption to hospital and social care services. This virus infection causes an explosive vomiting and diarrhoea with rapid onset and little preliminary warning that the patient is about to be ill. The vomitus and diarrhoea are heavily laden with the virus and the aerosols created by both are key to its rapid spread among contacts. The virus can spread directly by aerosol to the mucous membranes (mouth, nose, pharynx) of people in the same area. It will also contaminate items throughout the environment that can then themselves be a source of infection when those items of furniture, fittings, equipment, etc. are handled. The infection has a very high attack rate among those exposed and the postinfection immunity is generally very short-lived, so previous infection provides little protection. Both patients or residents and staff are usually affected in these outbreaks. Control of norovirus infection requires prompt and vigorous infection control precautions.

Fortunately, although unpleasant and debilitating when it occurs, norovirus infection is usually short-lived and recovery is quick in most patients. The acute vomiting and diarrhoea symptoms usually last for only 36–48 hours and most people then have only a few days of convalescence before feeling well again. Staff are usually able to resume work about 72 hours after the vomiting and diarrhoea has ceased, by which time they are no longer infectious. However, in health and social care settings where patients and residents are elderly and often frail, with severe underlying conditions, norovirus can be a more severe disease with significant associated morbidity and some mortality.

4 Scale of the HCAI problem—prevalence and incidence

An assessment of the number of cases of HCAI and the risk of infection for different patient groups is based on a series of different measurements. Point prevalence studies have been undertaken in many countries to give a snapshot of the number, and the percentage, of patients with any type of HCAI in a particular healthcare setting on a specific day.Prevalence studies in various developed countries over the last decade have shown overall prevalence rates between 5% and 10% (Table 16.1). A prevalence study in the four UK countries and the Republic of Ireland in 2006 showed an overall prevalence of 7.6%, ranging from 4.9% in the Republic of Ireland to 8.2% in England. The low rates in the Republic of Ireland probably reflected a rather younger patient population overall and the higher number in England was linked almost entirely to much higher numbers of cases of CDI (2006 was the height of the epidemic of CDI in hospitals in England). The commonest types of infection were urinary tract infection, followed by skin and soft tissue infections and wound infections, respiratory infections, and gas-trointestinal infections (Table 16.2). Bloodstream infections accounted for only 7% of HCAIs but represent the most severe end of the spectrum of disease. MRSA infections of all types accounted for 16% of the HCAIs and CDI was 17% of the total in hospitals in England but only 5% in Wales, Northern Ireland and the Republic of Ireland.

Table 16.1 Prevalence of healthcare-associated infections (HCAI s): international comparisons

Source: Commissioned research, National Audit Office (2009).

Country Year Prevalence of all HCAIs (%)
EU 2007 7.6
UK 2006 7.6
Denmark 2003 8.7
France 2006 5.4
Greece 2000 9.3
Italy 2002 7.5
The Netherlands 2007 6.9
Portugal 2003 8.7
Sweden 2004–6 9.5
USA 2006 5.0–10.0
Canada 2002 10.5

Table 16.2 Comparative prevalence of different types of healthcare-associated infections (HCAI s)

Source: Four-country HCAI prevalence survey, 2006 (Smythe et al., 2008)

Type of infection Percentage of all HCAIs
Lower respiratory tract 21
Gastrointestinal (diarrhoea/vomiting) 21
Urinary tract 20
Surgical site 14
Skin and soft tissue 10
Bloodstream (bacteraemia) 7
Others 7

Prevalence studies provide valuable comparisons between hospitals and countries and show the general contribution of the various types of HCAI. However, they do not represent the actual number of cases of different HCAIs over time, i.e. the incidence of infection in different hospitals, wards or patient groups. For example, a point prevalence of 8.2% does not mean that 8.2% of the patients admitted to the hospitals in England developed an HCAI because the infected patients tend to be more seriously ill and have longer stays in hospital both from their underlying illness and as a result of their HCAI; therefore, the incidence is always less than the point prevalence. Incidence is measured by ongoing and continued surveillance of specific infections in which all cases of the infection are recorded and related to the number of patients at risk. The HCAIs that are most commonly subject to surveillance programmes are bacteraemias (bloodstream infections) caused by specific healthcare-associated pathogens such as MRSA or ESBL-producing E. coli (because they represent the most severe types of HCAI), SSIs (one of the key indicators of the quality of a surgical service or an individual surgeon), and CDI. Surveillance data are necessary for monitoring infection prevention and control activities at national and regional level, which can provide useful comparisons between hospitals for patients who may choose where they wish to have their treatment. However, surveillance with timely feedback and data is particularly important at local level, within individual hospitals to ensure delivery of a high quality of care. Most surveillance programmes have depended on voluntary reporting of the infections to regional or national programmes but in several countries some high-profilveillance programmes have been made mandatory to ensure that infection prevention and control is made a high priority for health service managers and clinicians alike. Mandatory surveillance of MRSA bacteraemia was introduced in England in 2001, followed CDI, glycopeptide-resistant enterococcal bacter-aemia and SSIs in orthopaedic surgery in 2004. Similar approaches have been applied in other UK countries, the Republic of Ireland, European countries and the USA (mostly at an individual state level).

A further development of basic surveillance (i.e.reporting numbers of cases) is the application of enhanced surveillance in which information about patient demographics, risk factors, and outcomes is included. This can then be linked to root cause analysis of individual cases to provide valuable information about target areas for preventive measures.

4.1 What has surveillance told us?

Mandatory surveillance of MRSA bacteraemia in England showed a steady rise in cases to a peak of 7700 in 2004. Public and political concern about MRSA resulted in the government setting a target for a 50% reduction in MRSA bacteraemia over the 3 years 2005–2008. The surveillance data enabled active performance management through all levels of the (national) health service, provided pressures for improved infection prevention and control actions, and showed show the target was being achieved. Information from enhanced surveillance within this programme showed the importance of patients’ ages and underlying conditions as particular risk factors, and most significantly showed the importance of intravenous catheters and cannulae, renal dialysis catheters, urinary cath-eters and chronic wounds and ulcers as sites of MRSA infection leading to bacteraemia.

A similar approach was taken with CDI when mandatory surveillance showed that there were 55 000 cases in patients over 65 years of age in England in 2006; as these represent about 75% of cases, this means that there were around 70 000 cases overall. Guidance on prevention and control measures (based on the 1994 guidance) and a target to reduce the number of cases by 30% by 2011 focused activities in NHS hospitals and the 30% reduction was achieved within the first year (2008–2009).

SSI surveillance in orthopaedic surgery has been a national requirement in all UK countries for several years. This is a type of surgery with relatively low rates of infection (<5%) but surveillance has focused attention on infective complications, shown differences between surgical procedures, and also shown a steady improvement in rates in all the countries. However, the very short length of stay now usual for patients after these operations means that some infections only manifest themselves when the patient is at home. This has shown the need for including some system of postdischarge surveillance for surgical site infection to give a realistic picture of these HCAIs. This approach is being pioneered in the UK and the Republic of Ireland in relation to infections following caesarean section births where there is a clear opportunity for professional input to postdischarge sur-veillance because the mothers are seen at home by a midwife or health visitor.

4.2 The HCAI challenge

The surveillance programmes in various countries have shown the scale of the challenge set by HCAI in modern health and social care services. Why has this situation developed? There is a strong argument that during the last quarter of the 20th century, infections (including HCAI) had not been regarded as an important part of modern medical practice. There had been a view from the late 1960s onwards that infectious diseases had been conquered and that antibiotics and vaccines provided the answer. The importance of infection prevention and control measures was not given its former position in clinical training of doctors and nurses. Modern medicine was making tremendous progress in the treatment of malignant diseases, cardiovascular disease, transplantation, and chemotherapy, and in the management of chronic diseases. Life expectancy increased markedly and the proportion of very elderly people in the population, with their inevitable healthcare needs, rose rapidly. This created a vulnerable patient population at high risk of infection, but these infections were regarded as incidental nuisances rather than the major risk to a patients’ health and potential mortality which they are. Infections were regarded as the province of the infection specialists (medical microbiologists, infection control nurses) who had plenty of interesting work to do but a generally low profile. The situation changed with the advent of the 21st century and the recognition of the human and financial costs of HCAIs in a modern healthcare service.

5 Responsibility for HCAI prevention and control

The responsibility for infection prevention and control is shared across all who have a role in the delivery of health and social care, from the most senior managers to the most junior members of staff at ward or unit level—often described as the ‘board to ward’ approach. Clinicians (doctors, nurses and other professional colleagues) have a personal and professional responsibility for the care of their patients. Their responsibility for patient safety includes minimizing the risk of infection by implementing best clinical practice protocols, antibiotic stewardship, etc., and delivering the highest standards of clinical care and treatment for those who develop an infection, to treat those infections and minimize the risk of transmission to others.

Health and social care service managers and overseeing boards have an overarching responsibility for providing the corporate environment in which infection prevention and control has a high priority and all staff know what is expected of them. They need surveillance data and performance audits, coupled with inclusion of infection prevention and control in the individual performance review and personal appraisal of all their staff. In this way, infection prevention and control becomes embedded in the culture of the healthcare organization.

Governments, departments of health and health service national managers are the third party in this partnership. They are responsible for making HCAI prevention and control a top priority throughout health and social care services and holding local managers and boards to account for delivery of a high quality and patient care—and low rates of HCAI. They use performance management arrangements to require high standards from healthcare providers and can set targets for HCAI reductions (or ceilings for those with good records). They decide which HCAIs should be subject to mandatory surveillance. Governments also have the ultimate authority in terms of legislation that may be used to support HCAI prevention and control. The UK government was the first to use this type of legislation in relation to healthcare in England. The Health Act 2006 implemented a statutory code of practice for the prevention and control of HCAI.

This code of practice required all NHS bodies to:

• have appropriate management systems for infection prevention and control.

• assess the risks of acquiring HCAI and take actions to reduce such risks.

• provide and maintain a clean and appropriate environment for healthcare.

• provide information on HCAI to patients and the public.

• provide information when patients move from one healthcare body to another.

• ensure co-operation between organizations

• provide adequate isolation facilities.

• ensure adequate laboratory support.

• adhere to policies and protocols applicable to infection prevention and control.

These clinical care protocols included.

• standard(universal) infection control precautions

• aseptic technique.

• major outbreak protocols.

• isolation of patients.

• safe handling and disposal of sharps.

• prevention of occupational exposure to blood-borne viruses including prevention of sharps injuries

• management of occupational exposure to blood-borne viruses and postexposure prophylaxis.

• closure of wards, departments and premises to new admissions.

• disinfection policies.

• antimicrobial prescribing policies.

• reporting of HCAI to the Health Protection Agency as directed by the Department of Health.

• policies for the control of infections with specific alert organisms.

The code of practice also required NHS bodies to ensure (as far as reasonably practicable), that healthcare workers are free of and/or protected from exposure to communicable diseases during the course of their work, and the staff are suitably educated in the prevention and control of HCAI. The latter duty within the code of practice reinforced an essential element for all approaches to prevention and control of HCAI—a requirement for education and training of all healthcare workers on the rinciples of infection prevention and control and the part they need to play.

The combination of all these elements represents the fact that there is personal and corporate responsibility for HCAI prevention and control at all levels in any health and social care system.

6 Keys to infection prevention and control

There is no single ‘silver bullet’ to solve the challenge of HCAI. Infection prevention and control requires a combination of actions and activities, each of which provides an essential component to the whole.

6.1 Management and organizational commitment

The commitment of senior management to making infection prevention and control a high priority sets a culture of a health of social care organization. Management should monitor surveillance and audit data at all levels of the organization (‘from board to ward’) and ensure that all the staff play their part. This helps general a culture of pride in delivery of a quality service.

6.2 Surveillance

Up-to-date surveillance data on the incidence of key infections should be collected, analysed and returned to the clinical units with minimum delay. In this way the data are seen to be ‘real’ by the staff responsible for the care of the patients. It is now mandatory in several countries to collect surveillance data on MRSA infections (particularly bacteraemias), CDI, and some type of surgical site infections. Although national data collection is focused on whole hospitals or hospital groups, effective action within hospital depends upon the data being assessed and acted upon in individual wards or other clinical units, The essential nature of surveillance data is encapsulated in the dictum ‘you have to measure it to manage it’.

6.3 Clinical protocols

There are two main reasons why patients are at risk of developing an HCAI—their underlying medical condition making them vulnerable to infections and the treatment and clinical interventions they are subjected to. These interventions often include invasive procedures that bypass the normal defences of the skin, urinary and respiratory tract. It is, therefore, essential that clinical staff exercise all due care and attention when performing these procedures. To this end, an approach to clinical practice has been developed variously known as ‘care bundles’ (in the USA in particular) and ‘high-impact interventions’ (HII; the UK approach). These bundles are care protocols setting out in a simple bullet-point format the five or six essential elements needed to minimize the infection risk associated with the individual aseptic procedures. The aim is for each element to be performed correctly on every occasion and the care bundle/HII incorporates a simple audit tool for self-or peer-assessment on a frequent and regular basis of the performance of the clinical staff doing those procedures. The procedures that had been the main focus of the bundles comprise the following invasive interventions:

• central intravenous catheter insertion and maintenance (Table 16.3)

Table 16.3 High-impact intervention no. 1: central venous catheter care bundle

CR-BSI, catheter-related bloodstream infection.

Source: DH (2007) Saving Lives: Reducing Infection, Delivering Clean and Safe Care. Department of Health, London.

Insertion actions  
Catheter type Single lumen unless indicated otherwise,
Gastrointestinal (diarrhoea/vomiting) 21
  Consider antimicrobial impregnated catheter if duration 1–3 weeks and risk of CR-BSI high
Insertion site Subclavian or internal jugular
Skin preparation Preferably use 2% chlorhexidine gluconate in 70% isopropyl alcohol and allow to dry
  If patient has a sensitivity use a single patient use povidone-iodine application
Personal protective equipment Gloves are single-use items and should be removed and discarded immediately after the care activity
  Eye and face protection is indicated if there is a risk of splashing with blood or body fluids
Hand hygiene Decontaminate hands before and after each patient contact
  Use correct hand hygiene procedure
Aseptic technique Gown, gloves and drapes as indicated should be used for the insertion of invasive devices
Dressing Use a sterile, transparent, semipermeable dressing to allow observation of insertion site
Safe disposal of sharps Sharps container should be available at point of use and should not be overfilled; do not disassemble needle and syringe; do not pass sharps from hand to hand
Documentation Date of insertion should be recorded in notes
Ongoing care actions  
Hand hygiene Decontaminate hands before and after each patient contact
  Use correct hand hygiene procedure
Catheter site inspection Regular observation for signs of infection, at least daily
Dressing An intact, dry adherent transparent dressing should be present
Catheter access Use aseptic technique and swab ports or hub with 2% chlorhexidine gluconate in 70% isopropyl alcohol prior to accessing the line for administering fluids or injections
Administration set replacement Following administration of blood, blood products—immediately
  Following total parenteral nutrition—after 24h (72h if no lipid)
  With other fluid sets—after 72h
No routine catheter replacement  

• peripheral intravenous cannula insertion and maintenance

• renal dialysis catheter insertion and maintenance

• surgical site infection (wound) care

• care of ventilated patients

• urinary catheter insertion and care.

For the HCAI programme in England these were set out in packages called ‘Saving Lives’ for secondary care and ‘Essential Steps’ for primary care use. The packages were complemented by a care bundle for CDI and guidance presented in a similar way based upon key elements for antibiotic prescribing, isolation and cohorting of infected patients and the collection of blood cultures which form the basis of the diagnosis of a bacteraemia.

6.4 Isolation and segregation

One of the most basic and ancient approaches to preventing the spread of infection (or ‘contagion’ in previous centuries) is isolation of the affected patient. Segregation of infected patients from those vulnerable to infection (including various forms of quarantine) is an essential element of all infection prevention and control practice. It is particular important in HCAIs where the infection often occurs in vulnerable or debilitated patients and in a setting where transmission of infection between patients can occur readily. In many hospitals, the number of single rooms available for patient isolation is limited. The best use of the available rooms should be made for those with infections, but where the capacity of single rooms is exceeded by the number of cases of infection, it may then be necessary and appropriate for patients with the same infection to be nursed together in a cohort ward physi-cally separated from other ward areas and with dedicated staff who do not move between the cohort ward and other clinical areas (i.e. cohorting should apply to nursing staff as well as patients).

6.5 Hand hygiene

One of the main routes of transmission of HCAI pathogens such as MRSA is via the hands of healthcare workers as they move between patients. For many years staff were recommended to wash their hands between patient contacts and especially before and after performing clinical procedures. However, very frequent hand washing is time consuming, can damage the skin if done as often as should be required, and can also be quite impracticable when there is inadequate provision of wash-hand basins for staff. The answer to this problem has been the introduction of alcohol hand rubs that can be used repeatedly and quickly at every point of patient contact. Alcohol is highly effective against vegetative bacteria causing HCAI such as MRSA and the Gram-negative bacteria. The hand rubs should be made available at every patient bedside and in every clinical area, and at the entrance to cubicles and single rooms. Personal dispensers can also be carried attached to a belt or the clothing of healthcare staff to use as they move between patients. In many hospitals, alcohol hand rub dispensers have also been placed at the hospital entrance and/or at every ward entrance to emphasize to patients and visitors, as well as staff, the absolute importance of hand hygiene. However, the crucial times and places for hand hygiene relate to direct clinical contact with patients. The hand hygiene campaign based on alcohol hand rubs has been promoted internationally by the World Health Organization (WHO) and in the UK by the National Patient Safety Agency through its ‘cleanyourhands’ campaign. The WHO campaign high-lights the five opportunities (and requirements) for hand hygiene:

• before touching a patient

• before clean/aseptic procedures

• after body fluid exposure/risk

• after touching a patient

• after touching patient surroundings.

The need for effective and appropriate hand hygiene has also been included in all the care bundles/HIIs (see above).

However, in one area of infection prevention and control, hand hygiene with alcohol hand rubs does not replace the absolute requirement for hand washing: this is in relation to diarrhoeal infections caused by norovirus or Cl. difficile.Alcohol is not effective against norovirus or against the spores of Cl. difficile, so for these common diarrhoeal infections, hand washing is essential before and after each patient contact or contact with the environment around infective patients.

The audit of hand hygiene (alcohol hand rub and hand washing) is an important part of monitoring compliance with clinical protocols for infection prevention and control and should include direct observation of all grades of healthcare staff and also measurement of the volume of alcohol hand rub and liquid soaps used as a general proxy measurement of hand hygiene practice.

6.6 Environmental cleanliness and disinfection

Whenever there are problems or outbreaks of HCAI, there is popular outcry over dirty hospitals, giving the impression that environmental cleanliness equates to prevention of infection. Whereas there is no question that hospitals and other healthcare premises should be clean and that a clean environment promotes good healthcare practice, there is less of a direct correlation between general cleanliness and rates of HCAI. However, there is good evidence that bacteria and viruses from infected patients contaminate the general environment around those patients from where they can be picked up, e.g. on the hands, by other vulnerable patients or by healthcare workers and transmitted to other patients. The evidence is particularly clear with C. difficile spores, which can be found on all environmental services in rooms where there are patients with CDI. They are par-ticularly prevalent around toilets, or on commodes, or near bed pan washers.

General hospital cleaning is based on a detergent and water cleaning regimen, but when there are patients with known HCAIs, it is advisable to supplement detergent cleaning with use of environmental disinfectants. This is particularly the case in outbreaks of norovirus or CDI. The most effective disinfectants for these viruses and for the spores of Cl. difficile are those based on chlorine-releasing agents (see Chapter 19). These should be used routinely in areas where there are cases of norovirus or CDI.

6.7 Antibiotic prescribing

Good antibiotic stewardship and the prudent use of these valuable drugs is an important part of the prevention and control of HCAI. Most bacterial HCAIs are caused by antibiotic-resistant organisms that flourish under the selective pressure of antibiotic use, and because of the fact that many of the bacteria are resistant to several different types of antibiotic, even the use of individual antibiotics can select for bacteria resistant to a wide range of agents. Furthermore, many of the resistance genes are carried on transferable genetic elements that can transfer among bacterial populations, particularly in a selective environ-ment such as a hospital. There are many examples of links between use of particular antibiotics and cases of HCAI caused by resistant organisms. There are also more general links between use of agents such as the fluoroqui-nolone antibiotics and the rising incidence of MRSA colonization and infection. With CDI, the link is even more direct with the use of broad-spectrum antibiotics being a key precipitating factor for this disease. Outbreaks of CDI have been linked to widespread use of cepha-losporins and, more recently, fluoroquinolone antibiotics when the Cl. difficile strains such as ribotype 027 have been specifically resistant to these agents.

All healthcare organizations should have antibiotic prescribing protocols to promote and audit good stew-ardship. This is a requirement of the statutory Code of Practice in England. The guidance in the ‘Saving Lives’ package recommends that antibiotic stewardship pro-gramme should have the following elements:

• a prescribing and management policy for antimicrobials

• a strategy for implementing the policy

• an antimicrobial formulary and guidelines for antimicrobial treatment and prophylaxis

• decision to prescribe should be clinically justified and recorded

• intravenous therapy should only be used for severe infections or where oral antimicrobials are not appropriate

• intravenous antimicrobials should only be used for 2 days before review and switch to an oral agent where possible and appropriate

• all antimicrobial prescriptions should include a stop date—generally a maximum of 5–7 days without represcription

• daily review of antimicrobial treatment

• antimicrobial treatment reviewed on the basis of microbiological results

• minimize the use of broad-spectrum antimicrobials

• a single dose at induction of anaesthesia for most operations where antimicrobial prophylaxis is indicated

• training in implementing antimicrobial prescribing guidance for all prescribers

6.8 Training and education

The implementation of the range of infection prevention and control practices in any health or social care setting can only be successful if there is a comprehensive approach to staff education and training through which all can learn that everyone has a role to play in preventing HCAI. Basic training in infection prevention and control is mandatory for all staff in many hospitals and healthcare settings in the UK, Europe and North America, usually with regular (generally annual) required updates and specialist training for particular professional groups. Completion of this training is generally a require-ment for successful appraisal and performance review for all staff.

6.9 Audit

Whereas surveillance of key HCAIs is necessary for monitoring the changing pattern and the incidence of infections, audit of implementation of clinical protocols is equally necessary for maintaining a high level of infection prevention and control practice. There should be regular audits of hand hygiene compliance, adherence to antibiotic prescribing guidelines and the implementation of the clinical protocols in the care bundles/HIIs. The results of these audits should be reviewed in a timely manner at all levels of management in the health and social care organizations so that those implementing the protocols have ownership of the procedures and their effective application. Performance management at all levels depends upon a combination of the data from surveillance of the infections and audit of the clinical practice.

7 Zero tolerance and the principles of infection management

As a result of the implementation of the measures outlined above, the rates of particular HCAIs have fallen significantly in several countries. The application of the central venous catheter care bundle by intensive care units in the USA has resulted in a steep reduction in cases of catheter-related bacteraemia and, in some cases, long periods with no such infections. In England, the package of measures aimed at MRSA bacteraemias resulted in a 65% decrease in cases reported from the 2004 target base-line to 2009. These improvements have enabled the promotion of a zero tolerance approach to HCAI. This does not mean that there will be no infections (this is microbiologically and clinically implausible) but does mean that we can apply a zero tolerance approach to avoidable infections and to poor clinical practice such as inadequate compliance with hand hygiene requirements and imprudent antibiotic prescribing. The aim is to do everything right every time.

The general principles of infection management apply to HCAIs as they do to all types of infection, but it is particularly important to have reliable application of the principles where there is the risk of spread amongst vulnerable patients. Clinical staff need to have a high index of suspicion that a patient may be developing an infection and initiative appropriate confirmative diagnostic tests quickly. There should be prompt isolation of a patient suspected of being infected and specific treatment instituted along with infection prevention and control measures to prevent further spread. As well as these universal principals, there are some specific prevention and control measures aimed at particular infections.

7.1 MRSA

The reductions in MRSA bacteraemia achieved in UK hospitals and elsewhere as part of the targeted approach has been mostly the result of emphasis on hand hygiene,improved aseptic practices and the care bundles/HII approach for invasive procedures, particularly intravenous central catheter and peripheral cannula insertion and care. Implementation of these measures has been backed by the commitment of managers to reduce infection rates. These general improvements in infection prevention and control procedures would also be expected to help prevent other courses of bacteraemias linked to intravenous catheters and cannulae.

The further measure that is specific to the prevention of MRSA infections overall (wound and soft tissues infections, VAP, etc., as well as bacteraemias) is screening of patients before admission to hospital (when admission is planned or ‘elective’) or on admission in respect of emergency admissions. The principles behind such screening are that colonization of the nose and/or skin sites generally precedes clinical infection and that a colonized patient (otherwise referred to as a ‘carrier’) is at risk of developing an MRSA infection themselves and also a potential source of transmission to others. For such screening a swab is taken from the anterior nares, and also from the other skin carriage sites of perineum and axilla if considered appropriate, as well as from any surface lesions such as a chronic ulcer. Laboratory examination of the swab can be based upon convention selective culture for MRSA (which has a minimum turnaround time of 24–48 hours) or more expensive molecular methods based on PCR (polymerase chain reaction) methodology when a rapid result is considered to give significant benefit. Patients found to be colonized with MRSA are generally then given a ‘decolonization’ or ‘suppressive’ treatment regimen of nasal mupirocin cream and an antiseptic skin wash and shampoo for 5 days. This is very effective in reducing the bioburden in MRSA colonization in the short term, thus reducing the risk of infection for the individual patient and the risk of transmission to other. However, colonization may recur over a period of several months in 40% or more individuals. Nevertheless, the suppression of colonization will have covered the period of particular vulnerability and the time when they would be more likely to be a source of transmission. Screening and decolonization were part of the ‘search and destroy’ approach to MRSA infection developed in the UK in the1980s. It was also adopted elsewhere and has continued to be very effective in helping maintain low levels of MRSA infection and low levels of colonization in countries such as the Netherlands, parts of Scandinavia, and Western Australia. This approach was not maintained in most parts of the UK during the1990s but has been reintroduced as part of the MRSA control measures in various ways in the UK countries in more recent years. Screening of all patients admitted to NHS hospitals has been introduced in England, whereas other countries have adopted wide-spread but more restricted, risk-based approaches to selecting patients for screening. The risk factors are generally age (>65 or 70 years), previous MRSA carriage, previous hospital admission, residence in a nursing home or residential care home, and the presence of a chronic disease. The most appropriate approach will become evident as these different regimens are applied in different healthcare settings.

Screening for Staph. aureus more generally, not specifically MRSA, has been used as part of outbreak control measures over many years but has not been adopted on a routine basis. However, modern approaches to MRSA screen could also enable screening for any Staph. aureus strain in particular vulnerable groups.

7.2 Clostridium difficile infection

The emergence of CDI has been a complication of modern medical care compounded by inadequate attention to antibiotic stewardship and infection prevention and control measures. Elderly patients are the most vulnerable to this infection (75% of cases are in people >65 years old) but severe disease can occur in younger patients also. The major precipitating factor is the use of broad-spectrum antibiotics. In the UK, guidance produced in 1994 was reviewed and an updated document was pub-lished in 2009. This recommended the application of a mnemonic protocol (SIGHT) for managing suspected and then proven cases:

Suspect that a case of diarrhoea maybe infective when there is not a clear alternative cause for the diarrhoea

Isolate the patient and contact the infection control team

Gloves and aprons must be worn for all contact with the patient and their environment

Hand washing with soap and water before and after each contact with the patient and their environment

Test the stool for Cl. difficile toxins by sending a specimen immediately.

CDI itself then needs to be treated as a major diagnosis in its own right (not just a minor complication of the underlying disease). Sufficient isolation capacity is required for single room accommodation of cases, but in outbreak situations it may be necessary to cohort patients in designated CDI isolation wards. Cleanliness and use of sporicidal disinfectants (currently only chlorine-releasing agents are recommended) are important in CDI control.

There should also be a major focus on antibiotic stew-ardship. The guidance recommends that hospitals should establish antimicrobial management teams comprising antimicrobial pharmacists, consultant microbiologist, or infectious diseases specialist, and other clinicians as appropriate. The team should develop restricted guide-lines to promote the use of narrow-spectrum agents and avoid, where reasonably possible, clindamycin and the second-and third-generation cephalosporins (especially in elderly patients), while minimizing the use of fluoroquinolones, carbapenems and prolonged courses of aninopenicillins.

7.3 Norovirus

It is difficult to prevent norovirus introduction because of the rapid onset of illness, but it should be stressed to all staff, patients and visitors that people should stay away from health and social care settings if they or their families are suffering from this type of vomiting and diarrhoea. When cases occur in health or residential care settings, prompt action is essential. Patients should be isolated at the first signs of the infection (which is often dramatic onset of the vomiting and diarrhoea). Patients or residents and staff who were in the same area should be quarantined to reduce the risk of wider spread as more cases occur in those exposed. Individual cases often trigger outbreaks and as soon as this is recognized to be happening, the ward or residential unit should be closed to further admissions until the outbreak has ended amongst those (patients/residents and staff) already exposed. Because of the extensive environmental contamination, cleaning and disinfection of the affected areas is an important part of control. Areas contaminated with vomitus and faeces, which is common in these infections, should be promptly cleaned and disinfected with chlorine-based disinfectant. When the outbreak is over, patients or residents need to be moved elsewhere and a thorough deep clean of the affected area (ward, unit, etc.) including disinfection with a chlorine-releasing disinfectant should be done before any patients or residents are readmitted.

8 Professional support for infection prevention and control

Throughout this chapter, it has been stressed that infection prevention and control are the responsibility of all staff (clinical, managerial and support staff). However, it is also an area that requires the leadership and expertise of clinicians specifically trained in infection prevention and control. All healthcare and social care organizations should have access to such expertise and should have an infection prevention and control team and committee to deliver the expert service and support for the staff of all the clinical and social care units. The infection control team in hospitals should generally comprise nursing, medical and pharmaceutical professionals with specific training and expertise in infection prevention and control and in antibiotic prescribing. The nurse should be a trained infection prevention and control practitioner and the medical input is generally provided by a consultant medical microbiologist or infectious diseases physician whose training and experience has included the specific area of HCAI prevention and control. The pharmacist member of the team should have specific experience and expertise in antimicrobial prescribing. The team has an important role in outbreak investigation and management but, most importantly, provides the guidance and support for the delivery and effective infection prevention and control throughout the hospital or health and social care organization.

9 References and further reading

DH (2007) Saving Lives: Reducing Infection, Delivering Clean and Safe Care. Department of Health, London.

DH (2006) Essential Steps to Safe, Clean Care. Department of Health, London.

DH (2009) Health and Social Care Act 2008—Code of Practice for the Prevention and Control of Healthcare Associated Infections. Department of Health, London.

DH and Health Protection Agency (2009) Clostridium Difficile Infection: How to Deal with the Problem. Department of Health, London.

National Patient Safety Agency (2004) Ready, Steady, Go! The Full Guide to Implementing the cleanyourhands Campaign in your Trust. National Patient Safety Agency, London.

National Audit Office (2009) Reducing Healthcare Associated Infections in Hospitals in England. 12 June 2009.

Smyth, E.T.M. et al. on behalf of the Hospital Infection Society Prevalence Survey Steering Group (2008) Four country healthcare associated infection prevalence survey 2006: overview of the results. J Hosp Infect, 69, 230–248.

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Jun 20, 2016 | Posted by in PHARMACY | Comments Off on Public health microbiology: infection prevention and control
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