A healthcare-associated infection (HCAI) is defined as any infection that occurs in the course of a patient’s treatment in a hospital or healthcare facility, but which was not present or incubating at the time of the patient’s admission. It also includes infections that are acquired in hospital, but that do not become apparent until after discharge, as well as occupational infections that are acquired among healthcare staff.

According to the Health Protection Agency 2012, the six most common HCAIs are:

  1. Pneumonia/lower respiratory tract infections
  2. Urinary tract infections
  3. Surgical site infections
  4. Clinical sepsis
  5. Gastrointestinal infections
  6. Bloodstream infections

Most public or private healthcare providers take healthcare-associated infections very seriously. Depending on the provider they be regarded as 'significant harm events'. Modern healthcare providers are focusing on rapid diagnosis in order to provide effective treatment and to inform their infection control strategies. 

Patients who are most at risk of contracting an HCAI include the elderly or very young, patients admitted to an intensive care unit, long term in-patient stays, the use of invasive surgical devices or immunosuppression due to surgery or trauma or treatment.



1 in 25 patients gets a hospital acquired infection (HAI)


HAIs cost the NHS over £1,000,000,000 per annum


HAIs kill more each year than breast cancer & prostate cancer combined

Alert organisms/alert conditions

Alert organisms or alert conditions are a specified list of microorganisms/infections which on identification must be referred to a suitably qualified Infection Prevention and Control nurse (IPCN) for investigation. This investigation may also require a root cause analysis (RCA) to establish the index case of infection and the like vectors of transmission.  

Typical alert organisms may include:


MRSA is a type of bacteria that's resistant to several widely used antibiotics. This means infections with MRSA can be harder to treat than other bacterial infections. The full name of MRSA is meticillin-resistant Staphylococcus aureus, you might also have heard it called a 'golden staph' because often the infected pus is yellow/gold in colour. 

MRSA lives harmlessly on the skin of around 1 in 30 people, usually in the nose, armpits, groin or buttocks. This is known as "colonisation" or "carrying" MRSA and does not normally cause any symptoms.

However, people staying in hospital are most at risk of developing an MRSA infection because:

  • there is a way for the bacteria to get into their body, such as a wound, burn, feeding tube, drip into a vein, or urinary catheter
  • they may have other serious health problems that mean their body is less able to fight off the bacteria
  • they're in close contact with a large number of people, so the bacteria can spread more easily

Clostridium difficile

Clostridium difficile, also known as C. difficile or C. diff, is bacteria that can infect the bowel and cause diarrhoea. The infection most commonly affects people who have recently been treated with antibiotics but it can spread easily to others.

Patients have and increased risk of acquisition if they:

  • have been taking antibiotics that work against several types of bacteria (broad-spectrum antibiotics) or several different antibiotics at the same time, or over a long period of time
  • have had to stay in a healthcare setting, such as a hospital or care home, for a long time
  • are over 65 years old
  • have certain underlying conditions, including inflammatory bowel disease (IBD), cancer or kidney disease
  • have a weakened immune system, which can be caused by a condition like diabetes or as a side effect of a treatment such as chemotherapy or steroid medication
  • are taking a medication called a proton pump inhibitor (PPI) to reduce the amount of stomach acid they produce
  • have had surgery on their digestive system

C. difficile bacteria are found in the digestive system of about 1 in every 30 healthy adults and often live harmlessly because other beneficial bacteria in the bowel keep it under control. Some antibiotics can interfere with the balance of bacteria in the bowel, which can cause the C. difficile to multiply and produce toxins that make the patient ill.

When this happens, the patients' diarrhoea contains the C. difficile bacteria which can easily be spread in the environment or on the equipment within the hospital facility. Once out of the body, the bacteria turn into resistant cells called spores which can survive for long periods on hands, surfaces (such as toilets), objects and clothing unless they're thoroughly cleaned and decontaminated.


CPE is an acronym for a group of bacteria known as carbapenemase-producing Enterobacteriaceae, also know as CRO (Carbapenem resistent organism) or CRE (Carbapenem resistent Enterobacteriaceae). Enterobacteriaceae are bacteria that usually live harmlessly in the gut of humans, often known as colonisation. However, if the bacteria get into the wrong place, such as the bladder or bloodstream, they can cause infection.

Personal hygiene and cleanliness of the hospital environment and equipment is extremely important in preventing the CPE infections spreading. Important areas to pay attention to are:

  • single room patient accommodation (isolation)
  • dedicated toilet, preferably en-suite, facilities
  • dedicated patient equipment such as commode, IV pole, pillows and furniture 
  • mandatory use of gloves and long sleeved gowns on all staff and visitors when entering the room
  • strict adherence to hand hygiene protocols for all staff and visitors 
  • careful attention to surface cleanliness using approved disinfectants 


VRE is an acronym for vancomycin-resistant enterococci. Enterococci are bacteria that can live in the gastrointestinal tract of most healthy people without causing an illness. Vancomycin is an antibiotic used to treat infections caused by enterococci and when enterococci become resistant to vancomycin they are called vancomycin-resistant enterococci (VRE).

Sometimes VRE can get into other parts of the human body and cause an infection. Patient groups most at risk of getting a VRE infection usually have a reduced immunity due to another treatment they are undergoing such as:

  • chemotherapy for cancer
  • dialysis 
  • intensive treatments such as ventilation or intubation
  • organ transplants
VRE is spread easily from person to person by touch or from indirect contact with equipment and surfaces within the healthcare facility. VRE can sometimes get into the bloodstream from an existing infection, such as an abscess or a urinary tract infection, or from a medical device, such as a urinary catheter or a drip into a vein. 


Acinetobacter species belong to a group of Gram-negative bacteria that are readily found throughout the environment including drinking and surface waters, soil, sewage and various types of foods. Healthy individuals are at low risk of infection by Acinetobacter species. Acinetobacter infections acquired in the community are very rare and most strains found outside hospitals are sensitive to antibiotics.

A few species, particularly Acinetobacter baumannii, can cause serious infections in hospital patients who are already very unwell. These ‘hospital-adapted’ strains of Acinetobacter baumannii are sometimes resistant to many antibiotics and the infections that they cause can therefore be difficult to treat.



Infection prevention and control in hospitals

The application of, and compliance with, infection prevention and control (IPC) in hospitals is crucial to the effective management of patient care. Most healthcare providers have established experienced teams of suitably trained nursing staff (infection prevention nurse or IPN) and consultant medical experts to create and deliver the infection prevention and control strategy for the organisation. 

The role of the IP&CT

The IP&CT’s responsibilities include: providing evidence-based best practice advice; ensuring the safety of patients, staff, the general public and the environment; authoring the annual IP&C report; and ensuring compliance with the relevant code of practice.

To prove compliance with the code of practice most hospitals will need to demonstrate the following:

  1. That they have systems in place to monitor and manage the prevention and control of infection 
  2. That they provide and maintain a clean and safe environment 
  3. That they ensure appropriate antimicrobial use to optimise patient outcomes whilst also reducing the risk of antimicrobial resistance
  4. That they provide suitable, accurate and timely information on infections to service users, visitors and carers
  5. That they promptly identify those who have, or are at risk of developing, an infection
  6. That they have systems in place to make all carer workers aware of their responsibilities with regards to infection prevention and control
  7. That they provide adequate isolation facilities
  8. That they have adequate access to laboratory support
  9. That they have, and adhere to, policies for patient care to prevent and control infections
  10. That there are systems to manage occupational health needs and obligations of staff in relation to infection prevention and control.

The immune system

The role of the human immune system is to prevent the invasion of microorganisms such as  bacteria, fungi, viruses and protozoa. 

How successful the immune system is, depends on its ability to distinguish between ‘self ‘antigens (molecules that belong on the cell’s surface) and ‘non-self’ antigens (foreign cells or microorganisms that are invading the host). 

When the immune system recognises as antigens as being ‘non-self’ it initiates the innate immune response.



The innate immune response

The innate immune response is present from birth and is the first line of defence against infection. It is a nonspecific response, however, which means it does not provide long-lasting immunity.

Mechanical defence mechanisms of the innate immune response:

  • The skin - which acts as the main external barrier and which microorganisms find hard to penetrate
  • Skin pores, hair follicles and sweat glands - which are protected by the secretion of toxic chemicals such as fatty acids
  • Mucosal membranes - that protect the gastrointestinal respiratory and genitourinary tracts by secreting thick layers of mucus

Biochemical defence mechanisms of the innate immune response:

  • Phagocytosis - a nonspecific mechanism which involves the engulfing and killing of microorganisms by phagocytes (specialised white blood cells which originate in the bone marrow)
  • Neutrophils - the most numerous white blood cells in the blood which migrate to the site of infection and produce pus
  • The complement cascade system - a set of proteins that circulate in the bloodstream and that are activated by the presence of microorganisms in the host
  • Membrane attack complex (MAC) - which damages the walls of Gram-negative bacteria
  • Natural killer cells (NKCs) - which detect virally infected cells and destroy them
  • Major histocompatibility complex (MHC) - a set of molecules found on the cells of vertebrates and that indicate abnormal cell function - when detected they trigger the NKCs to begin apoptosis (cell death)

The actions of the innate immune response are often sufficient to destroy invading microorganisms. 

The acquired immune response

The acquired immune response is the secondary immune response which comes into play when the innate immune response has failed to destroy an invading microorganism.

It is highly specific, it is able to respond to virtually any antigen it has previously come across and it retains a memory of these previous encounters - which helps to prevent the body being reinfected with the same microorganism.

However, while the acquired immune response is highly effective, it is much slower than the innate immune response  - sometimes taking up to 10 days to fully mobilise. 

Activation of the acquired immune response

Macrophages and lymphocytes (branch-like cells found in the skin) play a key role in the activation of the acquired immune response.

When a foreign antigen enters the body it will eventually come into contact with a lymphocyte with a matching receptor. 

The cell with the ‘best fit’ will then divide to produce a large number of clones which will attack the microorganism.

There are three groups of antigen receptor cells which contribute to the acquired immune response:

T and B lymphocytes - which have unique antigen receptors that provide specific immunity (B cells also produce soluble antigen receptors, or antibodies, which react specifically with the antigen that has stimulated their production) 

Major histocompatibility complex (MHC) - a group of antigen receptors, found in all vertebrates, that function by presenting antigenic peptides to the T cells

The complement system

The complement system plays a major role in the acquired immune response by:

  • Enhancing the effectiveness of antibodies
  • Aiding phagocytosis of antigens
  • Attracting macrophages and neutrophils by chemotaxis
  • Causing cell lysis (death) 
  • Clumping pathogens together

It can be activated by the lectin pathway, the mannan-binding lectin (MBL) pathway or the classical pathway.

Autoimmune diseases

Because the acquired immune system is an anticipatory system, it can sometimes generate ‘anti-self’ receptors which trigger autoimmune diseases (Graves disease, Type 1 diabetes, Guillain-Barre syndrome, Celiac disease etc)


The formation of attenuated (weaker forms of) ‘live’ vaccines provides a way for a less virulent form of a microorganism to trigger an immune response. The aspect of ‘memory’ also means that when a similar or identical antigen is encountered, the immune response is faster and more expansive.


Clinical microbiology

The isolation of organisms within a laboratory is reliant on the creation of a setting that mimics the normal conditions under which that cell would normally grow whether in its host or in the environment.

The goal of culturing bacteria in the laboratory is to grow a population of cells (or colony) that is 20-30 divisions of a single cell. 

The rate of bacterial growth is dependent on several factors:

  • Nutrients - water, oxygen, carbon dioxide, carbohydrates, iron, trace elements etc which are broken down by the bacteria and used an energy source
  • Oxygen - certain types of bacteria grow better in an oxygen-rich environment while others prefer an oxygen-deprived environment
  • Temperature - bacteria will cease to grow if the temperature drops below (or rises above) their optimum growth temperature. Pathogenic bacteria mostly grow at normal body temperature (37 degrees C)

Processing a clinical specimen

The first stage in processing a clinical specimen is the inoculation of either a solid or liquid culture medium:

If using a solid culture: 

  • A swab (inoculum) is rubbed over a quarter to one third of the surface of a Petri dish containing a solid culture medium such as agar 
  • A sterile wire is used to ‘streak’ the inoculate over the surface of the medium
  • The lid of the Petri dish is replaced to avoid decontamination and the wire is ‘flamed’ in order to remove residual bacteria
  • The process is repeated with the original inoculate being spread into three sections, reducing with each spread
  • Bacteria that are well separated from each other will grow as isolated colonies and can be assumed to have been formed by a single organism or organism cluster

If using a liquid culture:

  • The nutrient broth will be inoculated from the plated specimen via an inoculating wire or loop
  • The specimen will be incubated (aerobically or anaerobically) for 24-36 hours and will be observed for growth
  • Nutrient broth will become cloudy due to the increased growth of bacteria
  • Culture plates will normally grow a mix of bacteria (including normal body flora) so the colonies can be inoculated onto another plate containing a more selective culture medium
  • Bacteria grown in a liquid culture can also be inoculated onto a solid culture medium for identification 


Bacterial classification is key to determining the appropriate antibiotic therapy. So once an organism has been cultured it will need to be identified. Because bacteria are naturally colourless, Gram staining is used to identify differences in the bacterial cell wall.

The specimen is first transferred, and heat fixed to a glass slide., before being covered with blue dye (crystal violet) which is washed off after thirty-seconds and decolourised with acetone. The acetone is then removed and a red dye (safranin) is applied for one minute. The slide is then washed and blotted dry. 

If the bacteria are Gram-positive they will stain blue-black.

If they are Gram-negative they will stain red-pink.

The high lipid content of the bacterial cell wall of mycobacteria means they cannot be Gram-stained, but will instead need to be identified using the Ziehl-Neelson staining method.

Testing for antibiotic susceptibility and sensitivity

To test for antibiotic susceptibility, bacterial colonies are isolated from the culture plate and inoculated onto a new agar plate. 

Antibiotic-impregnated paper discs are then placed onto the plate and immediately begin to diffuse into the agar. 

Bacteria that are susceptible to antibiotics will form a zone of inhibition around the disc. Those that are resistant will grow right up to the edge.


Identifying the genus and species of bacteria, and differentiating between different strains, is carried out in a specialist PHE Reference Laboratory. Typing techniques can also be used to determine the evolution of the strain and any emerging pathogens or clones

Infection prevention and control

An introduction to improving infection prevention & control in healthcare environments

Why hospital hygiene is crucial for ensuring patient safety, enhancing patient flow and reducing operational costs.

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An antibiotic is defined as a microorganism that is effective in killing (bactericidal) or inhibiting (bacteriostatic) the growth of another microorganism. The term antibiotic originally applied to naturally occurring organisms such as penicillin, however it now also includes the manufacture of synthetic and semi-synthetic antibiotic compounds. 

Antibiotics are used in the treatment of bacterial infections. ‘Microbial agents’ are any natural or synthetic agents used to treat a range of infections including bacteria, viruses, fungi, parasites and worms.

Therapeutic drug monitoring (TDM) is used to determine the trough levels (the level of drug in the bloodstream) over the course of treatment. If the trough level is too high the antibiotic will be toxic to the patient - if it is too low this can indicate a missed dose, a prolonged period between doses or an insufficient therapeutic dose.

The key characteristics of antibiotics are:

  • Selective toxicity - their ability to kill or inhibit bacteria without harming the host
  • Degree of toxicity - which is calculated using the therapeutic index to ensure the therapeutic dose (the amount needed to treat the patient) does not exceed the toxic dose (the level at which the dose becomes too toxic for the patient)
  • Spectrum - ie narrow spectrum antibiotics (where their effectiveness is limited specifically to either Gram-positive or Gram-negative bacteria) OR broad spectrum antibiotics (that are effective against a wider range of bacteria but which can also kill or harm resident flora)

The choice of antibiotic and how it is administered depends on the organism and its sensitivities, the site of infection and the patient history. Intravenous antibiotics, for example, may be required for the treatment of systemic infections or in cases where the patient cannot tolerate the drug orally.

Antibiotics can act in the following ways:

  • By disrupting the synthesis of the bacterial cell wall - ie penicillins; first, second and third generation cephalosporins; bacterial and broad spectrum carbapenems; bactericidal glycopeptides and bacteriostatic glyclines - that prevent the cell from forming or that cause it to burst
  • By inhibiting the synthesis of bacterial protein  - ie bacteriostatic (or bactericidal) macrolides - that work by shutting down the area of the cell responsible for protein manufacture
  • By inhibiting the synthesis of nucleic acid - ie fluoroquinolones, oxazolidinone and nitroimidazole - which disrupt the coiling and uncoiling of cell DNA or that prevent DNA from being transcribed into RNA
  • By perforating the membrane of the bacterial cell wall - ie cyclic lipopeptides - which are effective against most Gram-negative bacteria 

The principles of antimicrobial stewardship

  • Prescribe the right drug, in the right dose, at the right time, in the right duration - to every patient
  • Do not prescribe if there absence of a clinical sign of infection
  • Obtain clinical cultures before prescribing (but do not delay treatment if there is risk of a potentially life threatening infection)
  • Maintain a record of all prescribing, duration, route, dose and review date 
  • Use the IV route of administering only in the case of severe infection, if adequate blood levels aren't achieved, if there is an inability to absorb through the gut, if the patient is unable to tolerate the drug orally or if the drug is being used as a surgical prophylaxis

Antimicrobial resistance

The discovery of penicillin, and the development of antimicrobial agents, have transformed the way in which infections and infectious diseases are treated. 

However the growing global issue of antimicrobial resistance  - the ability of a microorganism to thrive in the presence of an agent that would normally kill it or inhibit its growth - presents a major challenge to modern healthcare.

The first signs of antimicrobial resistance were identified just ten years after the initial mass production of antibiotics, when strains of Staphylococcus aureus were found to have developed resistance to penicillin. The first reported case of Meticillin-resistant Staphylococcus aureus (MRSA) was reported in 1963.

Antimicrobial resistance can be inherent (ie when it is part of the organism's genetic makeup) or it can be acquired (developing naturally over time due to a genetic mutation or recombination).

The overuse and misuse of antibiotics is a significant contributor to the rise of antimicrobial resistance including:

  • Indiscriminate prescribing
  • The over-the-counter availability of antibiotics in some countries
  • The prescription of antibiotics where there is no genuine need 
  • The use of antibiotics as a prophylactic or preventative measure for longer than recommended
  • An inadequate dose of antibiotics or an insufficient period of antibiotic treatment which means an infection isn't able to fully resolve
  • The veterinary use of antibiotics in animals that have been bred for human consumption, which enables resistant bacteria to be transferred from animals to humans via the food chain
  • Intense or long-term exposure to broad spectrum antibiotics
  • Foreign travel to countries where there are higher rates of resistant organisms

Antimicrobial resistance is affected by a variety of factors in the hospital or healthcare environment including:

  • Higher bed occupancy rates
  • Increased patient to staff ratios 
  • Human activity that contaminates the environment with antimicrobials and accelerates the rate of antimicrobial resistance
  • Inadequate sanitation infrastructure or insufficient sanitation strategies, which can enable resistant microbes to persist and grow within plumbing systems such as sink drains
  • The breakdown of infection prevention and control practices such as hand hygiene or environmental decontamination 
  • The expectation of many patients that antibiotics will be freely prescribed

Combating antimicrobial resistance

Antimicrobial resistance is a complex global problem that affects not only human health but also animal health, welfare and security.

In 2013, the UK’s Department of Health (DH) together with the Department for Environment, Food and Rural Affairs (DEFRA) formulated a five-year antimicrobial resistance strategy.

The strategy targets 7 key areas:

  1. To improve infection prevention and control practices at a national and international level
  2. To optimise prescribing practices so the right drug is used at the right time and for the correct duration
  3. To encourage professional education, training and public engagement around the common myths, expectations and effectiveness of antibiotics
  4. To develop new diagnostics, treatments and drugs which differentiate between viral and bacterial conditions and enable faster identification of drug-resistant strains
  5. To provide better access to local, regional and national surveillance data to better understand the emerging issues in human and animal health
  6. To improve the identification and increased prioritisation of antimicrobial resistance
  7. To foster a greater level of international cooperation in combating the problem of antimicrobial resistance

Animal health and welfare

The responsible use of antibiotics in livestock is also acknowledged as being key to tackling the challenge of antimicrobial resistance.

In November 2018, the UK Government announced the establishment of an International Reference Centre for Antimicrobial Resistance, with the aim of reducing the use of antibiotics in animals by 25% by 2020.


The chain of infection

Healthcare acquired infections (HCAIs) are the result of sequence of events that take place between an infectious agent (or pathogen), a host and an environment. This process is known as the 'chain of infection' and is comprised of six ‘links’.

1. The pathogen 

Infectious agents or pathogens include:

  • Viruses - such as Influenza A, shingles and Hepatitis
  • Bacteria - including Lyme disease and Leptospirosis
  • Fungi - for example Candidiasis and Aspergillosis
  • Parasitic protozoan diseases - such as Malaria, Giardia and Toxoplasmosis
  • Prions - which are the cause of rare progressive neurodegenerative disorders such as Creutzfeldt-Jakob disease (CJD)

How well any pathogen is able to thrive depends on three elements:

  • Pathogenicity - the pathogen's ability to produce disease
  • Virulence - the pathogen’s severity or harmfulness
  • Invasiveness - the pathogen's propensity to spread

2. The reservoir

The reservoir is the principal environment in which a pathogen is able to live, flourish and multiply.

Common reservoirs for infectious agents include humans, animals, insects and the environment.

Human reservoirs

In humans, there are two forms of reservoir: acute clinical cases (in which someone is infected and is displaying signs and symptoms of the disease); and carriers (in which an individual has been colonised with an infectious agent but is not feeling unwell.)

Acute clinical cases are more likely to be diagnosed and treated - and the patient's contacts and normal activities will normally be restricted. 

Carriers can present more of a risk to those around them because they don’t exhibit any signs or symptoms of illness.

Carriers can be further divided into four types:

  • Incubatory carriers - the people who are infectious even before their own symptoms begin
  • Inapparent carriers - where an individual is able to transmit the infection to others, but never develops the infection themselves
  • Convalescent carriers - those who are in the recovery phase of an illness and who continue to be infectious
  • Chronic carriers - someone who has recovered from, but who continues to be a carrier for, infection

Animal & insect reservoirs

Examples of animal or insect reservoirs include: 

  • Lyme disease - transmitted by ticks
  • Rabies - transmitted by dogs, cats, foxes and bats 
  • Salmonella - transmitted by poultry, cattle, sheep and pigs

Any infectious disease that is transmitted under natural conditions from animal to human is referred to as zoonosis.

Environmental reservoirs

The environment contains multiple reservoirs of infection including soil (which can act as a reservoir for Clostridium tetani, the causative agent of tetanus) and water (which is a reservoir for Legionella pneumophila, the causative agent of Legionnaires disease).

3. The portal of exit

The portal of exit is the route by which a pathogen is able to leave the reservoir or host. 

In humans the key portals of exit are:

  • Alimentary - vomiting, diarrhoea or biting
  • Genitourinary - sexual transmission
  • Respiratory - coughing, sneezing and talking
  • Skin - skin lesions
  • Trans-placental - transmission from mother to foetus

4. The mode of transmission

An infection can be transmitted from its reservoir to a susceptible host both directly and indirectly.

Direct transmission is generally instantaneous and takes place when there is direct contact with the infectious agent. Examples of direct transmission include: tetanus, glandular fever, respiratory diseases and sexually transmitted diseases.

Indirect transmission can occur through animate means (such as fleas, ticks, flies or mosquitoes) or via inanimate means (such as food, water, biological products or surgical instruments). Indirect transmission can also be from contact with a contaminated surface, airborne, when tiny particles of an infectious agent are carried by dust or droplets in the air and inhaled into the lungs.

5. The portal of entry

The portal of entry is the means by which an infection is able to enter a susceptible host.

Portals of entry into the human body include:

  • Inhalation (via the respiratory tract)
  • Absorption (via mucous membranes such as the eyes)
  • Ingestion (via the gastrointestinal tract)
  • Inoculation (as the result of an inoculation injury)
  • Introduction (via the insertion of medical devices)

6. The susceptible host

How susceptible any host will be depends on:

  • Their age - and in particular if they are very young or very old
  • Whether there is any presence of malnutrition or dehydration
  • Whether there is any underlying chronic disease
  • If the host suffers from immobility
  • If they are taking any medication which could disrupt or suppress their immune response
  • General resistance factors (such as mucous membranes, skin, cough reflex etc) that can help defend against infection

The healthcare environment can expose patients to infection risks that they may not encounter elsewhere. Understanding how infections become established, and how they are transmitted, is vital for effective infection prevention and control.

The breaking or disrupting of the chain can be achieved at any link: through rapid and accurate diagnosis; prompt treatment of infected patients; safe disposal of waste; sterilisation and disinfection of medical equipment and the implementation of an environmental decontamination strategy.



Environmental cleaning and disinfection

Environmental cleaning and disinfection are crucial to the prevention and control of infection within hospitals and healthcare facilities.

Pathogens and multidrug resistant organisms can easily be shed from infected or colonised patients and have been known to survive on dry surfaces for hours, days or even months at a time. 

There is growing evidence that contaminated surfaces are a key contributor to the transmission of person-to-person healthcare associated pathogens. And an estimated 20% to 40% of HCAIs are spread via the hands of healthcare workers.


Decontamination is the series of processes that are used to remove or destroy infectious agents and organic matter in order to prevent the spread of infection.


The first stage of decontamination is cleaning - or the physical removal (whether manual or automated) of dirt, dust and soil from surfaces. In healthcare environments this will normally involve a combination of water, detergent, cloths and mops and will normally be performed daily.

Enhanced cleaning

Enhanced cleaning refers to the methods used in addition to standard cleaning, and is done in response to a specific infection prevention and control requirement. 

Enhanced cleaning may involve increased frequency of cleaning - or the addition of other cleaning equipment or disinfectants. 

It is routinely undertaken at the point of discharge or transfer of a patient who has been known to be infected with a pathogenic microorganism.


While manual disinfection can help to reduce the number of viable infectious agents in the healthcare environment, it is not always sufficient on its own to inactivate certain microbes such as viruses and spores. In these cases, the use of a specific concentration of a chemical agent may be required. 

But while enhanced cleaning and disinfection has been proven to be successful in reducing HCAIs, studies have also shown that when cleaning is undertaken manually it is only ever partially effective - with only 50% of hospital ward surfaces being adequately decontaminated with the use of chemical disinfection. 

Specialist automated technologies, for example the use of hydrogen peroxide vapour or ultraviolet light, can play a vital role in supporting the efficacy of manual cleaning practices. However these technologies can only supplement (and never replace) standard cleaning.

There is also considerable evidence of the use of self-disinfecting surfaces (such as copper coated surfaces) in decreasing the prevalence of HCAIs.


Isolation/cohort nursing

Isolating infected patients in a single room is generally considered best practice in helping to isolate the organism, control its transmission and prevent the spread of infection. It should however be implemented until a risk assessment has been conducted.

Risk assessment factors

  • The patient - will the patient be safe in a single room, do they require close observation, are they at risk of self-harm, will isolation impact on the patient’s rehabilitation or general care?
  • The organism - what is it, how is it spread, is it antibiotic/multi antibiotic resistant, what are the complications of cross-infection?
  • The facilities - is a single room immediately available, is it in an observable area, are there en-suite facilities, is there a cohort ward the patient could be transferred to, would the patient be safer in an open ward alongside uninfected patients?
  • Equipment/environmental considerations - what equipment is required, can equipment be dedicated exclusively to the patient, what are the environmental decontamination requirements?

Categories of isolation

  • Source isolation - isolation of the patient in a single side-room
  • Protective isolation - undertaken within specialist oncology/haematology wards to protect patients who may be severely immunocompromised
  • Negative pressure isolation - achieved with the use of a ventilation system to protect contaminated air from mixing with clean air
  • Strict isolation - in the case of patients with rare infectious diseases, in which the patient is isolated in a negative-pressure patient isolator within a negative-pressure room
  • Cohort nursing - undertaken in situations where there are not sufficient single rooms to isolate patients. Patients will be cohorted according to the nature of the organism and/or the nature of their symptoms

Requirements of isolation/cohort nursing

  • Appropriate isolation signage on door/s to the room/bay
  • A closed door to the room/bay
  • PPE outside the room/bay
  • Alcohol hand rub, hand washing facilities within the room/bay
  • En-suite facilities
  • Domestic and clinical waste bins in the room/bay
  • Single patient use medical equipment (blood pressure cuff, tourniquet, lifting aids etc)
  • Disinfection wipes for decontamination of equipment and surfaces in the room/bay

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Investigation and management of outbreaks

Outbreaks of infection are common in acute hospital settings and can be caused by a wide variety of microorganisms.

Public Health England (PHE) defines an ‘outbreak’ as: ‘an incident in which two or more people experiencing a similar illness are linked in time or place’. The term ‘outbreak’ can also be applied to a single case of a rare disease - such as botulism, diphtheria, polio, rabies or Ebola.

The primary objective of outbreak management is to protect public health and safety by identifying the likely source and mode of transmission and implementing infection prevention and control measures.

In a hospital setting it is crucial that an initial investigation is carried out within the first 24 hours in order to clarify the nature of the outbreak and to determine whether an outbreak control team (OCT) will need to be convened. 

The OCT is responsible for agreeing a case definition, coordinating activities, conducting an investigation and ensuring that infection control measures are promptly implemented. The OCT will declare an outbreak to be over once there is no longer a risk to public health, the number of cases has declined or the probable source of infection has been identified and removed.

Key actions in the management of an outbreak

  1. Initial investigation within 24 hours
  2. Assessment of public health risk
  3. Declaration of outbreak
  4. Implementation of immediate control measures (hand hygiene, isolation, PPE, enhanced environmental cleaning)
  5. Identification, screening and specimen collection of contacts
  6. Treatment with antibiotics, antivirals, chemoprophylaxis or vaccination
  7. Prompt identification and treatment of new cases as they occur
  8. Liaison with local authorities, environmental agencies
  9. Regular review meetings with key stakeholders to monitor progress of outbreak
  10. Education of affected patients, their contacts and family members
  11. Completion of final report within 12 weeks of the outbreak
  12. Possible publication of the findings


Management of patients with infectious diarrhoea

The pathogens that cause infectious diarrhoea can be ingested (through the consumption of contaminated food or water) or transmitted through invisible contamination via the hands. They can then be spread to other patients via the faecal-oral route. 

Common causes of infectious diarrhoea include: Clostridium difficile, Giardia, Norovirus, E. coli, Campylobacter, Salmonella, Cryptosporidium, Shigella and Staphylococcus aureus.


An essential prerequisite for patient assessment is to establish the individual’s normal bowel function (consistency, frequency, type). Any pre-existing medical conditions, for example, may also mean that episodes of diarrhoea are considered normal for that patient.

A thorough history will also need to be taken to determine whether there is an infectious cause, including - the onset and duration of the symptoms, previous patient history of C. diff, associated signs or symptoms such as abdominal pain, fever or vomiting, the patient’s medical history (eg inflammatory bowel disease, abdominal or pelvic irradiation), any history of recent foreign travel, medication (antibiotics, laxatives, drugs etc), food history, recent contact with pets or farm animals.


If an assessment indicates a potentially infectious cause then the following investigations will be implemented: 

Stool specimen - ideally this should be obtained within the first 48 hours of illness when the pathogen is at its most acute phase

Blood tests 

  • White cell count - the number of lymphocytes, monocytes, neutrophils, eosinophils and basophils (which increase in the presence of inflammation or infection)

  • CRP (C-reactive protein) - an acute phase protein produced by the liver, normally found in low levels but which rises in response to inflammation

  • ESR (erythrocyte sedimentation rate) - the rate at which red blood cells separate and fall to the bottom of a test tube of anticoagulated blood


Depending on the results of the stool culture, antibiotics may be indicated. Antidiarrheal agents should not be administered as they decrease the fecal transit time and increase the risk of toxin retention, which can cause damage to the bowel tissue.

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Surgical site infection

Surgical site infection (SSI) is a wound infection which occurs after an invasive surgical procedure. It one of the most common HCAIs (accounting for around 16% of all HCAIs in England) and is a major cause of increased length of hospital stays, morbidity and mortality.  

  • Surgical factors - the presence of sutures or foreign bodies, the duration and complexity of surgery, quality of suturing, pre-existing local or systemic infection, prophylactic antibiotics, haematoma, mechanical stress on the wound
  • Anaesthetic factors - tissue perfusion (movement of fluid) , blood volume, body temperature at the time of the procedure, the concentration of inspired oxygen, the quality of pain relief
  • Patient-related factors - Advanced age, poor physical health, diabetes, smoking, alcoholism, renal failure, obesity, poor nutrition

SSIs are defined using a set of standard clinical criteria according to whether they affect the superficial tissues (skin and subcutaneous layer) or the deeper tissues (deep incisional or organ space.) 

The majority of SSIs are caused by endogenous infection - microorganisms (such as Staphylococcus aureus) that already present in the patient, whether on their skin (skin flora) or within an internal organ.

Exogenous infection occurs when external microorganisms contaminate the operative site. Sources of exogenous infection include surgical instruments, the theatre environment and the air. External microorganisms can also contaminate the wound at the time of an accident or following surgery before the wound has healed.

Most SSIs are preventable by applying measures at the point of pre, -intra, and post-operative phases of care. 

Practices to prevent SSIs 

  • Washing of the patient prior to surgery to remove/reduce the number of microorganisms that normally colonise the skin
  • The use of prophylactic antimicrobial therapy to prevent the multiplication of microorganisms at the operative site
  • Enhancing the patient’s infection defences by minimising tissue damage and maintaining normal core body temperature (normothermia)