chain of infection. objectives: chain of infection 1. list the factors involved in the chain of...
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Chain of infection
Objectives: Chain of Infection1. List the factors involved in the Chain of Infection2. State the key role of the nurse in relation to the chain of
infection3. Define the term ‘pathogen’4. Briefly explain what is meant by the term ‘reservoir’5. Outline the distribution of body flora, giving an example
from each site6. Briefly explain what is meant by the term ‘portal of exit’7. Define ‘mode of transmission’, differentiating between
contact, common vehicle, airborne and vector borne8. Briefly explain what is meant by the term ‘portal of entry’9. Outline the means by which the skin, mucous membranes,
the GI tract and the GU tract protect the body from infection
10. Explain what is meant by susceptible host
Objectives: Introduction to Microbiology
1. Briefly explain the importance of understanding microbiology in terms of the nurse’s role
2. List 4 types of micro-organisms3. Label a diagram of a typical bacterium
(indicating nucleic acid, cytoplasm, cell membrane, cell wall, capsule, ribosome, storage material, flagellum, pili
4. Briefly explain the function/s of the above structures
5. State the significance of the Gram negative and Gram positive terms
6. State three features which may be used to classify bacteria
7. List four distinct requirements for bacterial growth
Objectives: Introduction to Microbiology
8. Name the main method by which bacteria reproduce
9. Briefly explain the difference between viruses and other microbes
10. Give three example of common viruses11. Briefly explain the growth requirements
for viruses and method of reproduction12. Outline the main differences between
fungi and bacteria13. State which type of organism is
responsible for: hospital acquired infections, community illnesses, mycoses
Chain of Infection
The infective process involved in the development of disease hinges upon a complex interaction between:• Pathogen• Reservoir• Portal of exit• Mode of transmission• Portal of entry• Susceptible host
Together these factors are termed:
The Chain of Infection
Pathogen
Definition: Disease producing micro-organism
• Question: Are all microbes harmful?
• Question: Are some microbes beneficial?
• Question: Are these beneficial organisms ever harmful?
• What is the name for microbes that colonise the human body in health?
Breaking the Chain
Given the right circumstances , potentially all micro-organisms may cause disease
Nurses need to reduce this risk by:* Recognising the components and * Breaking the chain in as many places as possible
ReservoirDefinition: a location or environment where a micro-organism can survive and multiply
Reservoirs may be:* Animate e.g. human, animal,
bird, plant OR
* Inanimate e.g. food, water, air, soil, excreta, dust and fomites such as bedding or toys
Distribution of Normal Body Flora
Portal of Exit
Definition: Place from which the micro-organism escapes the reservoir e.g.
- Sputum- Blood- Vaginal secretions- Semen
Mode of Transmission
Definition: Route via which the micro-organism is transmitted to the host
Can be classified as:a) Contact
b) Common vehicle
c) Airborne / Droplet spread
d) Vector borne
e) From mother to baby
Mode of Transmission
Contact Direct
e.g. skin to skin
Indirect e.g. shared needles
Mode of Transmission
Common vehicleVia a common source such as contaminated food or water
Mode of Transmission
AirborneThrough contact with infected secretions produced when a person talks or sneezes.
Particles may be contained in:
* large droplets * droplet nuclei / dust
Mode of Transmission
Vector borne• Via insects or animals e.g. malaria
spread by mosquitoes
Mode of TransmissionFrom Mother to Baby
Pre-natal
Peri-natal
Post-natal
Portal of Entry
Definition: Route via which micro-organisms enter the host
This may occur via:Skin
Mucous membranes
Gastro-Intestinal tract
Genito-Urinary tract
Portal of Entry: SkinWhen intact – the skin is a very important barrier
The skin:… Acts as a mechanical barrier… Has a slightly Acid pH… Has skin flora
All the above provide a hostile barrier for pathogenic organisms
When breached – microbes may enter
Portal of Entry: Mucous membranes
Some protection via:… muco-ciliary clearance... lysozyme… secretion of a special antibody
However, ulceration, or loss of cilia can lead to microbes gaining entry via this route
Portal of Entry: GI TractThe GI Tract is protected by:… Acid pH of the stomach… Pancreatic enzymes… Bile… Normal flora of the tract… Peristaltic action of the gut
Portal of Entry: GU Tract
The GU Tract is protected by:… Frequent flushing of urine… Secretion of Ig A… Antibacterial action of sperm… Acid pH of vagina… Normal flora of the tracts
Susceptible host
Definition: An individual who succumbs to the effects of invading microbes due to breaches in exterior defences (e.g. skin or mucous membranes) and / or an inability to mount an immediate / sustained specific immune response
Preventing the spread of infection:Role of the Nurse
Disruption and blockage of chain of infection
Protection of susceptible patients
Prevention of Infections
PrimaryIncrease the resistance of the
patientInterrupt the chain of infection Restrict the spread of infection
SecondaryDetecting disease at earliest possible time to:
Begin treatmentStop progression Protect others
TertiaryLimit the progression of disabilityTreat symptoms and rehabilitate (varies with each specific disease)