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The importance of surveillance for hospital-acquired infections

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Hospital-acquired infections (HAIs) have long been recognised as major problems affecting the overall quality of health care (Gaynes and Solomon, 1996). Surveillance, however, has been identified as an important way to provide quality outcome indicators and identify key measures in order to reduce the burden of HAIs (Reilly et al, 2001).

VOL: 98, ISSUE: 23, PAGE NO: 56

Claire Kilpatrick, RGN, Dip ICN, is national HAI surveillance nurse; Jacqui Reilly, PhD, BA, RGN, is national HAI surveillance coordinator, Scottish Centre for Infection and Environmental Health, Glasgow.


Surveillance is defined as ‘the ongoing systematic collection, collation, analysis and interpretation of health data essential to the planning, implementation and evaluation of public health practice, closely integrated with the timely dissemination of these data to those who need to know’ (Centers for Disease Control, 1988).

The objectives of surveillance related to HAI include:

  • Monitoring infection incidence rates;
  • Monitoring trends, including the detection of outbreaks;
  • Providing early warning and investigation of infection problems, and subsequent planning and intervention to control;
  • Prioritising resource allocation;
  • Examining the impact of interventions;
  • Gaining information on the overall quality of patient care.

In summary, surveillance provides ways to identify and clarify quality issues, understand their causes and subsequently identify actions to bring about improvements, which is at the forefront of many health care services’ clinical governance agendas.

A Framework for National Surveillance of Hospital-Acquired Infection in Scotland (Scottish Executive Health Department, 2001) stated that Scottish trusts are now required to implement surveillance of HAI using standardised methodologies over defined periods. A new national team has been funded to help support this. England, Wales and Northern Ireland are already undertaking a variety of surveillance programmes, and with standardisation it will be possible to compare surveillance data. Local surveillance programmes have also been carried out around Scotland and clearly show areas in which it has achieved positive results. For example, Reilly et al (2001) demonstrated that surveillance of surgical site infections resulted in a significant reduction in infection rates, from 13.3% to 7.4%. This, in turn, led to reduced costs for the health authority.

There are many ways in which nurses can play a part in surveillance and help to reduce infection rates. In order to do this effectively, it is vital that they receive appropriate support and training from infection control personnel and existing surveillance and audit staff. In Scotland, the HAI Infection Control Standards Board (Clinical Standards Board for Scotland, 2001) will also have a growing influence, particularly in relation to compliance with fundamental infection control measures and associated surveillance programmes. England and Wales have similar control standards.

Surgical site infection surveillance

Surgical site infection (SSI) is a key area for surveillance, as it remains one of the important complications of surgery, resulting in high costs in both financial and human terms (Plowman et al, 1999). The National Audit Commission (2000) has also recognised the implications of HAIs on mortality and morbidity and the associated costs. In fact, the commission estimated that HAIs cost the NHS over £1bn per year.

When collected through surveillance programmes, SSI rates can be used to set standards by providing a baseline. Services can then be measured against this baseline as surveillance continues to demonstrate whether they are reducing rates of SSI. Haley (1985) demonstrated that it is possible to reduce infection rates by up to 38% by carrying out surveillance programmes and feeding back results to those involved in patient care. However, if surveillance of SSIs is to provide comparable and valid data, it is vital that the methods used to conduct it are standardised.

The key aims of SSI surveillance are to:

  • Collect data on SSIs, so that the risks to hospital patients can be estimated;
  • Analyse and report data, and therefore identify trends in specific infection rates;
  • Provide timely feedback of SSI rates to assist surgical units and trusts as a whole to minimise the occurrence of infections.

It is essential that people carrying out surveillance of SSIs are able to recognise them correctly. Training may be required to ensure that all nurses involved are able to do this in a standardised way.

A variety of definitions are used to identify wound infections, many of which are debatable and can be ambiguous and confusing for those using them. Definitions should be simple and unambiguous so that they can be applied consistently between different observers.

The definitions listed below are commonly used in SSI surveillance programmes to identify accurately different types of postoperative infections (Horan et al, 1992).

Superficial SSI (incisional)

Infection must occur no more than 30 days after the procedure and involve only skin and subcutaneous tissue of the incision. The patient must have at least one of the following:

  • Purulent discharge from the superficial incision;
  • Organisms isolated from an aseptically obtained culture of fluid or tissue from the superficial incision;
  • At least one of the following signs or symptoms of infection: pain or tenderness, localised swelling, redness or heat, and superficial incision is deliberately opened by the surgeon, unless incision is culture-negative;
  • Diagnosis of superficial incisional SSI by surgeon or attending physician.

Deep SSI (incisional)

A deep incisional SSI must meet the following criteria:

  • Infection must occur no more than 30 days after the procedure if no implant is left in situ - or within one year if there is an implant. It must also appear to be related to the procedure, and involve deep soft tissues of the incision.

The patient must have at least one of the following:

  • Purulent discharge from the deep incision but not from the organ/space component of a surgical site;
  • A deep incision that spontaneously dehisces or is deliberately opened by a surgeon when the patient has at least one of the following signs or symptoms: fever (>38°C) or localised pain or tenderness, unless incision is culture-negative;
  • An abscess or other evidence of infection involving the deep incision found on direct examination, during re-operation, or by histopathological or radiological examination;
  • Diagnosis of a deep incisional SSI by a surgeon or attending physician.

Organ/space SSI

An organ/space SSI involves any part of the body, excluding the skin incision, fascia or muscle layers, that is opened or manipulated during the operative procedure. Specific sites are assigned to organ/space SSI to further identify the location of the infection. An example is an appendicectomy with subsequent diaphragmatic abscess, which would be reported as an organ/space SSI at the intra-abdominal specific site.

An organ/space SSI must meet the following criteria:

  • Infection must occurs no more than 30 days after the procedure if no implant is left in situ - or within one year if there is an implant. The infection must also appear to be related to the operative procedure and involve any part of the body, excluding the skin incision, fascia, or muscle layers, that was opened or manipulated during the operative procedure.

The patient must also have at least one of the following:

  • Purulent discharge from a drain that is placed through a stab wound into the organ/space;
  • Organisms isolated from an aseptically obtained culture of fluid or tissue in the organ/space;
  • An abscess or other evidence of infection involving the organ/space that is found on direct examination, during re-operation, or by histopathological or radiological examination;
  • Diagnosis of an organ/space SSI by a surgeon or attending physician.

How is SSI surveillance carried out?

Many methods can be used to carry out both in-patient and post-discharge surveillance, and nurses can be involved in these at various stages. Clear national and local guidance and definitions must be provided, with training to accompany these, to ensure accuracy. The methodology adopted is crucial in determining the reliability and validity of the surveillance programme.

Surgical site infections are currently considered to occur up to and including 30 days postoperatively. While the patient is in hospital, the methodology may consist of:

  • Completion of surveillance forms, starting in theatre;
  • Direct observation of wounds postoperatively at set intervals, to observe for the defined signs and symptoms of infection;
  • The use of medical, nursing and laboratory records and ward staff as sources of information when completing the data on surveillance forms;
  • At the end of the surveillance, forms being sent to a local coordinator for collation and reporting.

Post-discharge surveillance can be more complex, and finding an efficient and cost-effective way to do this is a constant consideration for both trusts and national expert groups. Some methods include:

  • Direct observation of patients’ wounds during follow-up visits, either at a clinic or in the patient’s home;
  • Review of medical records retrospectively after follow-up out-patient clinic visits;
  • Patient surveys by postal questionnaire or telephone;
  • Clinician surveys by postal questionnaire or telephone.

It is well recognised that infection rates are under-reported if the surveillance programme does not incorporate post-discharge surveillance (Bruce et al, 2001), and this is therefore an essential component in order to gather accurate data. The most reliable method has been noted to be direct observation of patients’ surgical sites (Bruce et al, 2001).

Who should be involved in SSI surveillance?

It is essential that the multidisciplinary team is involved, including infection control staff, surgeons, theatre and ward nurses, surveillance nurses, clinical nurse specialists and staff working in audit teams and administration.

What else can nurses do to reduce or prevent SSIs?

Nurses should be aware of any surveillance programmes in their area, and ensure that they act on any feedback provided from them. Data should be made available at regular intervals, for example monthly, so that nurses can use the information to enhance their practice and monitor their actions associated with SSIs occurring in their area. Preventive measures are essential to ensure infection risks are reduced or minimised during the patient’s surgical stay. In addition to surveillance, link nurses, frequent education, and local audit programmes to review procedures can be used to support and monitor actions being carried out. Liaison between clinical areas and the infection control team should be ongoing throughout.

The Centers for Disease Control published guidelines for prevention of SSIs (Mangram et al, 1999) after reviewing all the published evidence on the risks related to SSIs. Nurses can play a part achieving in a number of recommended prevention measures:


  • Ensuring patients are in optimum health before going for surgery;
  • Only removing hair if it will directly interfere with the operation site, in which case it should be removed using electric clippers as close to the surgery time as possible.

In theatre

  • Ensuring all finger nails are kept short and without nail polish;
  • Not wearing hand or arm jewellery;
  • Performing a pre-operative scrub for at least two to five minutes using an appropriate antiseptic;
  • Decontaminating all equipment and the environment thoroughly;
  • Wearing a theatre cap to cover hair on the head and face when entering the theatre;
  • Adhering to the principles of asepsis;
  • Assembling sterile equipment and solutions immediately before use.


  • Ensuring a sterile theatre dressing stays in situ for 24-48 hours to ensure that primary closure has taken place at the incision site;
  • Washing hands before and after changing the dressing and on any contact with the site;
  • Removing drains as soon as possible.
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