Give
an account of infections transmitted via blood and blood products. How can
health workers protect themselves from acquiring such infections?
Outline:
·
Blood-borne infections:
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bacteria: pseudomonas spp., yersinia
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virus: HIV, hepatitis B
·
Precautions & preventive measures:
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general measures
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safe handling and disposal of sharps
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reduce risk of blood-skin contact.
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decontamination and waste disposal.
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management of exposed cases
Suggested
Answer:
Transfusion of blood and blood products carries a risk of transmitting
blood-borne microorganisms. Infection was common in the early days of blood
transfusion, when reusable collection sets were in use and blood was not
routinely screened for viral agents. The patients now at greatest risk of
transfusion-associated infection are either patients who have had multiple units
of blood (e.g. during cardiac surgery) or those who require blood products
pooled from many donors (e.g. haemophiliacs).
The microorganisms most commonly implicated are either bacteria or
viruses. Bacteria may cause overwhelming systemic sepsis, usually within minutes
to hours of the onset of transfusion. There is a high mortality rate when this
occurs. Viral infection has a much longer incubation period and may only become
clinically apparent months after transfusion. Bacterial infection is usually the
result of contamination at the time of donation, poor storage, contaminated
equipment or a combination of these. Viral infection is usually caused by the
presence of viral infection in the donor. Bacteria include Citrobacter spp.,
Pseudomonas spp. and Yersinia enterocolitica. Viruses include
hepatitis B and C viruses, human immunodeficiency virus and cytomegalovirus. A
severe acute transfusion reaction resulting from infection may take the form of
septicaemia.
Needle-stick and other sharp injuries are the most common means of
transmitting hospital-acquired HIV infection and hepatitis B. These injuries are
frequently the result of recapping of hypodermic syringe needles after
completion of venesection, but other reasons include encounters by domestic
staff with discarded needles hidden in bedlinen and pricking by sutures or
scalpel blades during surgical procedures. The common site of injury is the
thumb or forefinger of the non-dominant hand.
Healthcare workers should be advised to get themselves vaccinated against
hepatitis B virus. General measures to reduce the risk of exposure are washing
hands before and after contact with each patient, and putting on and after
removing gloves; change gloves between patients; cover existing wounds, skin
lesions and all breaks in exposed skin with waterproof dressings and avoiding
sharp usage wherever possible and where sharps usage is essential, exercise
particular care in handling and disposal.
Many percutaneous injuries are preventable. Implementation of the
following procedures for the safe handling and disposal of sharps will reduce
the risks: place all disposable sharps in sharps container after use; provide
sharps containers in adequate numbers and never overfill; avoid re-sheathing
needles manually; discard disposable syringes and needles wherever possible, as
a single unit and removing needles from syringes only when essential. Wearing of
gloves can reduce the risk of acquiring blood-borne infections and therefore
healthcare workers should wear gloves when using a sharp equipment or during
surgical procedures.
The following measures reduce risk of blood-skin contact: if a glove
puncture is suspected or recognized, rescrub if possible and reglove as soon
safety permits; change gloves regularly if performing, or assisting with a
prolonged surgical procedure; wear protective headwear or surgical masks; ensure
that all blood is cleaned from a patient’s skin at the end of an operation
before patient leaves theatre and removing protective clothing including
footwear when leaving the contaminated area.
Decontamination and proper disposal of medical equipments can prevent
occupational exposure to blood-borne infectious agents. Single use equipment
should be used where appropriate, particularly where decontamination cannot be
carried out effectively. Reusable equipment must be of a type that is readily
decontaminated without damage to its structure or function. Thorough physical
cleaning of instruments in warm water with detergent to remove blood and debris
is essential prior to disinfection or sterilization. All waste which is
contaminated with blood, tissues or other potentially infectious body fluids
should be treated as ‘clinical waste’ and disposed of properly. Clothing and
linen stained with blood or body fluids which is to be reused should be handled
with care and placed in suitable bags for safe storage and transportation for
laundering.
Sharps injuries should be reported to the supervising staff. Serum should
be taken from the patient and the staff member. The patient’s serum is then
tested for evidence of hepatitis B and C and when permission is given, for HIV
infection. The staff serum is stored for comparison with a further serum
specimen to demonstrate seroconversion, or for further testing if the
patient’s serum is hepatitis B positive. Staff will normally require
counselling regarding the risk of hepatitis and HIV infection. Transmission of
hepatitis B virus occurs far more readily than HIV. If the patient is hepatitis
B positive, the staff serum should be checked for antibodies to hepatitis B
surface antigen. If the titre is low or absent, a booster dose of vaccine is
required, along with a dose of hepatitis B immunoglobulin.