Disinfection

An important method of reducing the potential infectivity of viruses is dilution. Thus procedures such as thorough cleaning and handwashing are central to any infection control policy and must never be neglected.

The trend towards the use of disposables reduces the need for decontamination in many areas. Thorough cleaning followed by heat sterilisation should be adopted, if at all possible, for any reusable equipment. Although HIV is inactivated by boiling, autoclaving has become the norm in clinical practice. With increasing numbers of HIV carriers in the community it is important for their protection to ensure that instruments are rendered free of all organisms, including bacterial and fungal spores. Organisms that may present no risk to people with normal immunity may lead to opportunistic infections if they are immunocompromised by HIV infection or other agents such as chemotherapeutic drugs.

Liquid disinfectants must always be considered a poor alternative to heat sterilisation. Difficulties exist controlling their potency, most are caustic, and most are rapidly inactivated by organic matter. For hospital or community use, if it is necessary to use a liquid disinfectant, it is sensible to choose one which is known to inactivate hepatitis B and other pathogens such as Mycobacterium tuberculosis, as well as HIV.

All waste that is contaminated with blood must be considered potentially infective and treated as “clinical waste” in accordance with the Health Services Advisory Committee’s document “The safe disposal of clinical waste”.

Box 15.3 Disinfection

• Autoclave or use disposables if possible

• Hypochlorite (1000 ppm available chlorine) for general decontamination

• Hypochlorite (10 000 ppm available chlorine) if organic matter, including blood, present

• 2% Glutaraldehyde (freshly activated) NB: Beware of dangerous fumes

First aid and inoculation injuries

In the event of exposure to blood, simple first-aid measures should be applied immediately. Any blood or other body fluids on the skin should be washed away with soap and water. Splashes into the mouth or eye should be diluted by washing, and sterile eyewash bottles should be provided in any areas where this is likely to occur. A skin puncture should be encouraged to bleed in an attempt to express any material deposited in the wound. The wound should then be washed thoroughly. Any injury to a member of staff should be reported immediately to the person in charge and then to the occupational health physician or other medical adviser. In hospital this allows for the opportunity to investigate the state of health of the person inoculated and, if necessary, to take protective measures such as hepatitis B prophylaxis or antibiotic cover, or testing the source patient or the use of antiretroviral drugs. At present the recommended drugs for postexposure prophylaxis are zidovudine, lamivudine and indinavir. They should be taken for four weeks. An acceptable recommended alternative regimen is the use of nelfinavir instead of idinavir. However, allowances for pregnancy, drug interactions and potential antiviral resistance in the source may result in some modification to the final regimen. In these circumstances expert advice should be sought. The medical adviser should discuss whether blood samples should be taken for future reference of HIV testing and whether a programme of follow-up consultations should be started.

The medical adviser will need to obtain information about the source patient concerning possible indicators of HIV infection, including risk factors and results of previous HIV tests, medical history suggestive of HIV infection, and details of past and current antiretroviral therapy in patients known to be HIV infected. The source patient should be asked to consent to testing for HIV infection. This will entail pre-test discussion and obtaining fully informed consent. If the patient is unconscious when the injury occurs consent should be sought once the

Box 15.4 First aid

• Body fluids on skin, in eyes, or in mouth

wash away immediately

• Penetrating wounds

encourage bleeding wash with soap and water report to the supervisor and medical officer

patient has regained full consciousness. If the patient refuses testing, is unable to give consent because of mental illness or disability, or does not regain full consciousness within 48 hours, testing should be considered in exceptional circumstances only, such as where there is good reason to think that the patient may be HIV infected. In this case testing an existing blood sample for HIV infection may be done but only after consultation with an experienced colleague. The decision to test may be challenged in courts so be prepared to justify the decision. Only the source patient and those exposed to the infection may be told the result of the test and the result can only be entered into the patient's personal medical record with the patient's consent. If the patient dies HIV testing can be done if there is good reason to think the source patient may be infected. It is usual to seek the agreement of a relative before testing.

Those concerned with counselling people who have sustained inoculation injuries should have enough knowledge to provide current information about the risks of occupational exposure and should be able to advise on changes in lifestyle such as the adoption of safer sex practices.

In summary, the risk of transmission of HIV within hospitals and to carers in the community is low. Education of staff, good infection control procedures and safe working practices can help to minimise this risk. Due attention to these measures at all times will ensure the protection of patients and staff.

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