8 - Activities of a pathogen 1 Flashcards
What do I need to know?
Bacterial disease and how bacteria CAUSE disease
Pathogen
A microbe capable of causing disease i.e. and infectious agent.
Infection
An infection is where the microbe is established in the host
Colonisation
Colonisation is infection with a microbe for a varying period of time. During colonisation there may or may NOT be an immune response
Infectious Disease
Interaction with a microbe that causes damage to the host. Infectious disease can cause symptoms or it may not
Endogenous
Infectious disease arises from colonising pathogen or flora
Exogenous
- Infectious disease arises from elsewhere i.e. influenza is an exogenous cause of infectious disease as it is NOT living in the body
- includes human to human transmission and zoonosis and the environment
Zoonosis
Infectious disease is transmitted from another animal host
Where do most infectious diseases originate from
Most are endogenous and originate from within the body so have nothing to do with the external environment
Microbe
SUBmicroscopic, microscopic or macroscopic
What 3 things relate to infectious disease?
Host, pathogen/microbe, environment
What is an example of endogenous disease?
UTI - arises from bacteria already living in the urinary tract
What is a high risk / susceptible host
Someone that is currently not infected but is in a region of high prevalence or is at a high risk of being infected i.e. a healthy person living in an area with endemic malaria
What could make a person susceptible to disease
- Other illnesses i.e. HIV/chronic lung disease ^ risk of respiratory infection as cilia are damaged
- risk behaviours such as unprotected sex
- immune deficiency (inborn or acquired - often treatments interfere with the IS. Age also causes inactivity of IS due to immunosenescence)
- other factors; often don’t know why
Immunosenescence?
Immunosenescence is the state of immune deficiency caused by the immune system becoming relatively inactive in old age
Examples of exogenous
- human to human (common)
- environ and zoonosis
> both uncommon as the germs here don’t interact well with our cells and if they do our IS is usually effective against them
What is colonisation
It is the process by which a foreign particle infects a host. It is similar to sub-clinical infection. Most often colonisation does not cause symptoms and so does not cause the host any trouble. Occasionally there is an immune response and so rarely colonisation becomes infectious (damages the host)
Staph aureus is an example of a bacteria that often colonises humans in the nasal cavity and does generally NTO cause any issues
Colonisation
‘partly endogenous and partly exogenous)
When a microbe is not usually part of our flora but you will often find it in otherwise healthy people i..e no symptoms but there is an immune response. Colonisation occurs at various sites depending on the bacteria - staph aureus
Colonisation of bacterial helps prevent overgrowth of dangerous bacteria
We can also be colonised with bacteria that could harm us if they got into our blood/internal organs
What is a pathogen
A microbe that is capable to cause infectious disease
Primary pathogen
Isolation is always pathogenic (TB and gonorrhoea)
Principle pathogen
Isolation is USUALLY pathogenic and causes infection in otherwise well people with intact defences
Opportunistic Pathogen
Only causes infection when defences are down i.e. bacteria in soil
Where can infections occur
In the community or healthcare settings
Community onset infections
Community onset conditions are those easily transmitted like coughs, colds, influenza and there are generally annual episodes of certain community onset infections. Community onset infections are generally mild and don’t require treatment
