5.1. INTRODUCTION
5.1.1 There is a wide variety of units where the potential for the spread of infection may pose exceptional diffliculties. The feature common to these units is the presence of particularly vulnerable patients e.g. immunocompromised patients.
Infection is often seen as an inescapable outcome following aggressive and invasive treatments of patients in units of high potential risk, but the development of, and adherence to, appropriate infection control policies in these units reduce the potential for this.
5.1.2 The purpose of this chapter is to highlight some of the special problems which might be encountered in such units. Since there are authoritative texts which address this area, this chapter will not be a detailed treatise on the subject but will provide general principles and a framework for consideration.
5.1.3 Units of high potential risk may be treating patients who are immunocompetent e.g. Dermatology, but more often those who are immunosuppressed by disease or iatrogenically. Immunosuppressed patients vary in their susceptibility to HAI, this depending on the severity and duration of immunosuppression, but they are generally at increased risk of bacterial, fungal, parasitic and viral infection from both endogenous and exogenous sources.
5.1.4 For the purpose of this document units of high potential risk are regarded as those where patients may be expected to be colonised or infected with highly transmissible or epidemiologically important micro-organisms, or are at increased risk of becoming seriously ill because of infection (Table 5. 1).
The following represents a list of all the units where general, hospital-wide infection control policies may need to be adapted to meet specialist requirements. The ICT should be involved with these specialist units in drawing up additional measures for inclusion in the infection control policy.
|
Table 5.1 |
|
|
Units of High Potential Risk |
|
|
Intensive Therapy Unit (ITU) |
Transplant |
|
High Dependency Unit (HDU) |
Burns |
|
Trauma |
|
|
Haematology |
Neurosurgery |
|
Oncology |
Plastic Surgery |
|
Radiotherapy |
|
|
Elderly/Mentally Ill |
|
|
Neonatal Unit including Neonatal Intensive Care |
|
|
Maternity |
Endoscopy/Bronchoscopy Suites |
|
Paediatrics |
Operating Theatres |
|
Dermatology |
Pathology |
|
Renal Medicine |
Pharmacy/Supplies (see 5.4.6 below) |
|
Isolation Ward/Infectious Diseases Unit |
|
|
Phsiotherapy/Hydrotherapy |
|
5.2. MICRO-ORGANISMS
5.2.1 The micro-organisms which cause infection in units of high potential risk include those which are ordinarily associated with HAI. In addition, many organisms having little or no pathogenicity in healthy people can cause serious infection in settings where there are compromised patients.
5.2.2 Multiple drug resistant micro-organisms are an ever-present threat in these units. The selective pressure of heavy antibiotic usage and the presence of debilitated or immunocompromised patients encourages the emergence of these organisms. Multiply resistant Gram-negative bacteria, Staphylococcus aureus, Mycobacterium tuberculosis and vancomycin resistant Enterococci are all important contemporary pathogens. Control of the spread of these depends upon robust surveillance, improved compliance with handwashing and other routine precautions and antibiotic policies tailored to the individual unit. These issues must be discussed with the ICT and regularly "policed".
5.3. TRANSMISSION OF INFECTION
5.3.1 Transmission of infection within hospitals requires a source of micro - organisms, a means of transmission and a susceptible host. The risk of transmission depends upon the dose and virulence of the organisms, the duration of exposure and the degree of susceptibility of the host.
5.3.2 Sources of micro-organisms include other patients, staff and visitors, the patient's own endogenous flora and/or contaminated inanimate environmental objects and the building services, including equipment.
5.3.3 Transmission of infection occurs by three main routes, namely contact, droplet or airborne spread.
5.3.4 Needlestick injuries are an important potential source of transmission of Hepatitis B, C and HIV. This risk is greatest in units where the management of these patients tends to be concentrated e.g. infection units, liver transplant and haematology/marrow transplant units (see 8.6).
5.4. GENERAL PRINCIPLES FOR PREVENTING TRANSMISSION OF INFECTION
5.4.1 The primary strategy for successful control of infection in hospitals depends upon adherence to the standard precautions for prevention of infection, described in Chapter 4. Detailed instructions on the appropriate procedures to be followed will be found in the Trust Policy prepared by the ICT. These comprise Universal (blood and body fluid) Precautions and Body Substance Isolation. The former measures are designed to reduce the risk of transmission of bloodborne pathogens and the latter to reduce the risk of transmission of pathogens from other body fluids. The purpose of standard precautions is to reduce the transmission of micro-organisms from both recognised and unrecognised sources of infection in the hospital.
5.4.2 Where patients are shown (or suspected) to be colonised or infected with highly transmissible or epidemiologic ally important micro - organisms, or are at increased risk of becoming infected, measures over and above the universal precautions are required. These are Transmission-Based Precautions and should be used in conjunction with universal precautions. This means that, in addition to general, hospital-wide policies there is a need for units of high potential risk to identify specific additional measures to control infection within their area. These measures must be clearly stated in the Infection Control Policies and the Isolation Policy and must be prepared in consultation with the ICT.
5.4.3 In certain circumstances it might be necessary to consider preventing nosocomial infections by treating and controlling colonisation. Measures include eradicating exogenous pathogens from patients who have become colonised, suppression of normal flora or preventing colonising flora from entering sterile sites during invasive procedures. The ICT should be consulted about the use of such measures and drawing up policies for their implementation.
5.4.4 Clinical Laboratories, Mortuaries and Post Mortem Rooms
Clinical laboratories must comply with the current recommendations contained in authoritative guidelines e.g. Health Service Advisory Committee (HSAC) guidance on compliance with legislative requirements39.
Particular attention should be given to:
Safe working practices must be clearly specified in laboratory protocols and Trust policies and may be scrutinised by the HSE at any time.
For post mortem rooms similar considerations apply and the specific guidance is to be found in the relevant HSAC document40. (This guidance is currently under review.)
5.4.5 Burns Units
These units pose a particular infection control challenge. Planning for such facilities needs to take account of the changing epidemology of burn injuries but nevertheless have the capability of providing the highest standard of care for the small number of seriously burned patients and for the larger number with serious but not life threatening burns. The management of burned patients who require ventilation and the desirability of ultra clean air systems should be discussed with the specialists involved - surgeons, intensive care anaesthetists and the ICT. Guidance on building design and ventilation can be obtained from the HEEU (address in Appendix 5).
5.4.6 Pharmacies
The principal infection control hazard in pharmacies lies in the production of prescriptions for injection or infusion. Although the aseptic manipulations associated with such preparations is a professional matter for pharmacists,41,42 the ICT may wish to assure themselves that the necessary monitoring of these activities is implemented, assessed and reviewed.
5.4.7 Mental Health, Learning Disabilities and Care of the Elderly Environments
While it is accepted that the implementation of infection control policies and guidelines in these environments may be difficult due to poor patient understanding and compliance and the need to maintain as "normal" a lifestyle as possible, it is imperative that the principles of good infection control practice are not compromised. It is important that the healthcare professionals working in these units together with the ICT undertake a risk assessment and then tailor the infection control guidelines to ensure practical and effective implementation and good compliance within these environments.
5.5.1 Patient isolation is applied in two ways, namely source isolation and protective isolation. Local isolation policies will be determined by the ICT.
5.5.2 Source isolation entails the isolation of infected patients in order to prevent the transfer of their infection to others. A patient with a transmissible infectious disease e.g. salmonellosis or carriage of an epidemiologically important micro-organism e.g. MRSA, should be placed in a single room with dedicated handwashing and toilet facilities situated within the ward or located in an Infection Unit.
5.5.3 Protective isolation is the term used to describe methods of isolation for patients who are highly susceptible to infection and require special protection from the hospital environment. For example, during periods of severe neutropenia or profound/prolonged immunosuppression, additional measures are required to prevent acquisition of potential pathogens, particularly Aspergillus spp.
5.6. ENVIRONMENTAL MEASURES
5.6.1 Reducing infection rates depends on a variety of factors, notably staff procedures. In addition, environmental measures form a crucial component of the overall strategy. Some of these measures include attention to ventilation, the maintenance of hot and cold water systems and air conditioning systems, and steps to be taken when building work and maintenance is undertaken.
5.6.2 Special air handling and ventilation are required to prevent airborne bacterial transmission. The control of airborne contamination hinges upon effective distribution of the air in ventilated rooms. This depends upon ventilation efficiency, ventilation rate, and air movement relative to adjacent sites.
5.6.3 In a free-standing ITU, where there are single rooms which are entered via a gowning lobby, the air conditioning systems (including humidity control) should provide source or protective isolation.
5.6.4 For patients requiring protective isolation, the supply air must be HEPA filtered and supplied at positive pressure to prevent ingress of airborne pathogenic organisms. For source isolation the room should be at negative air pressure in relation to the surrounding areas, and should be discharged directly outdoors or HEPA filtered if the air is being circulated to other areas of the ITU/hospital, or exhausted near public areas or air intakes. Isolation rooms should be equipped with manometers which monitor the air pressure relative to the surroundings and activate an alarm should the desired pressure fail. Further information is available in Health Building Note No 27 intensive Therapy Units43 issued by NHS Estates for England and Wales.
5.6.5 For the remaining areas of such an ITU, air movement induced by mechanical ventilation should be from "clean" to "dirty" areas. Fresh air intakes should be filtered and tempered. External discharge from air systems should be protected against back pressure due to adverse wind effects and should be located to avoid the reintroduction of vitiated air into the ITU or other hospital areas via windows or fresh air intakes.
5.6.6 More importance is now being given to the maintenance and internal cleanliness of air system ductwork and items of plant and further advice is given in HTM 202525 . Where associated plant or equipment is subject to dampness or condensation, disinfection procedures using, for example a hypochlorite solution, will be required.
5.6.7 Patients on immunosuppressive therapy, particularly those with organ transplants, are susceptible to e.g. opportunistic hospital-acquired legionella infection. Legionella bacteria are present in many hospital water systems at varying concentrations. Not one of the methods currently employed to deal with the problem is able to ensure long-term eradication.
5.6.8 Guidance on the provision and maintenance of potable water supplies is given in BS670044 . Reference should also be made to HTM 204045 , HTM 2027 46 and Scottish Hospital Technical Note No. 2 47 . Although there are no nationally agreed guidelines concerning the design of water systems for transplant or isolation units, several successful systems have been installed in Scottish hospitals. Detailed advice should be sought from HEEU (address in Appendix 5).
5.6.9 In special circumstances, where patients receiving immunosuppressive therapy are being accommodated, regular disinfection of the water systems using a heat process or continuous chlorine dioxide dosing as a biocide might be considered (this would be exceptional and dependent on a risk assessment); the preference being the maintenance of water temperatures within the temperature ranges given in HTM 204045 and HTM 2027 46 with due regard to scalding by water above 43'C as advised by the Health Guidance Note "Safe" Hot Water and Surface Temperatures48.
5.6.10 Wet evaporative cooling towers associated with air conditioning should be maintained to eliminate the risk of widespread distribution of airborne legionella and other pathogens in the cooling water droplets. Such plant juxtaposed to a hospital can also be a source of infection through wind drift. The elimination of wet cooling towers, certainly within a hospital, is the preferred solution.
5.6.11 Structural/building work can, for example, be the source of aspergillus and care is required to protect patients, especially highly immunosuppressed patients, from such airborne fungi generated in and around new and refurbished works. The ICT should be consulted BEFORE such work takes place.
5.7. EDUCATION AND TRAINING
5.7.1 Patients in units where the risk of acquiring nosocomial infection is high usually have diseases which need specialist medical and nursing care. The risks of patients acquiring nosocomial infection whilst in such units are minimised by employing staff with the necessary experience and skills to permit a high quality of care and by ensuring an adequate staffipatient ratio. Specific education programmes and work protocols are needed for such employees.
5.7.2 It is recommended that units of high potential risk should establish a post for a trained infection control link nurse. Emphasis must be placed on having appropriate current infection control policies which should be reviewed at least annually and be strictly followed. This will reduce the risks of spread of HAI amongst patients and staff. There should be regular infection control education for all staff.
5.8. OCCUPATIONAL HEALTH
5.8.1 Although covered in detail in Chapter 8, it is worth re-emphasising here those aspects which are relevant to units of high potential risk.
5.8.2 When establishing the service level agreement with the organisation providing their OHS, Trusts with special units need to consider the implications of these areas upon staff pre-employment assessments. Because of the hazard to susceptible patients, issues which are not at present viewed as having universal concern may be relevant e.g. immunity to chickenpox (see Chapter 8). There is no evidence to support extensive microbiological screening of prospective staff although targeted surveillance may be appropriate e.g. for MRSA in those who have worked in areas with a high risk of the organism being present.
5.8.3 After the start of employment, staff should be educated to view illness in themselves with a high index of clinical suspicion as they are dealing with patients who may be particularly susceptible to infection which, when it occurs, can have serious consequences. Conditions which are trivial to the employee, e.g. cold sores, can have serious consequences for the susceptible patient. There should be agreed protocols in place for the management of such situations and no pressure should be placed on staff to work when they may represent a potential hazard to their patients.
5.8.4 It is well recognised that infection can be introduced into a unit by a member of staff who takes on additional employment at another healthcare facility. Employees working in units where the risk of patients acquiring nosocomial infection is high must be made aware of the hazard this represents and should be discouraged from undertaking such activity. In the event that an individual chooses to engage in extra work then that person has a duty to notify each employer if there is exposure to an infective organism e.g. MRSA, MRK at one site which may represent a hazard to the patients at the other centre.
5.8.5 Occasionally other staff working in the hospital, both internal Trust employees and external contractors, will have reason to visit the special units. Such episodes are under the supervision of the person in charge of the unit at the time. This individual should refer to the ICT as required and must ensure that all necessary infection control precautions relevant to protecting the worker(s) and the patient(s) have been enacted.
5.8.6 Appropriate policies and procedures for maintenance and repair of equipment must be in place.
5.9. VISITORS
5.9.1 Visitors, who may be relatives, carers or friends of patients and/or contractors of services e.g. construction, estates etc. may be sources of infection. Suitable regulations pertaining to visitors are imperative in the control of nosocomia,l infection e.g. in an ITU. An overall hospital policy should be formulated with the collaboration of the services concerned e.g. maternity services, and protocols should be drawn up in consultation with the ICT.
5.9.2 The visiting policy should take into consideration special risks of infection, the particular needs of the individual patient and the peak work periods of the staff. Certain patients may require special consideration and the visiting policy should permit flexibility at the discretion of the attending physician. For example, unlimited visiting privileges for parents on paediatric wards have been well accepted by staff in many hospitals as providing greater comfort and security for the child.
5.9.3 Certain areas require stricter controls because of the greater hazards from infection. When patients in special areas such as surgical recovery rooms, obstetrical delivery rooms, or intensive therapy units are permitted visitors they should adhere to the infection control procedures outlined by the clinician or the Ward Sister/Charge Nurse. It is unwise to allow children to visit patients in Infection Units and adults who are not considered to be immune to a particular infection, e.g. chickenpox, should be excluded from contact with that disease. A risk assessment should be undertaken by the health care professionals before children are allowed to visit individuals of high potential risk in hospital.
5.10. MANAGEMENT ARRANGEMENTS
The establishment of policies for specialised units requires the approval of the TICC and endorsement by the CE.