Lectures week 1-6.pdf - Microbiology An Introduction...

Microbiology
An
Introduction

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The microbial world
 Microorganisms are organisms that are usually too small to be seen
clearly with the naked eye

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Microbes in our lives
 Only a few microbes are harmful
– Less than 1% of bacteria can cause disease!
‐ bacteria ‐ cartoon.jpg
People, Peas and Pathogens: Image (wordpress.com)

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Why study microbiology?
 Microorganisms are part of the human
environment and are therefore important
to human health
– They are in us, on us, and nearly everywhere around us
 Microorganisms are essential to the
web of life in every environment
– Interact with other organisms
– help maintain balance of nature
‐ review ‐ your ‐ body ‐ mostly ‐ microbes
‐
microbiology/chapter/food ‐ preservation/

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Why study microbiology?
Vast majority of microorganisms are directly or indirectly beneficial
to humans and other organisms
– Food production
– Medicine
– Health
– Biotechnology
– Ecology

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Fields of microbiology

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Fields of microbiology

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Thank
you

Infection and Disease

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Infection and Disease
Infection
 Refers to the relationship between two organisms –
the host and the microbe – and the competition for
supremacy taking place between them
– A host with strong resistance remains healthy
– The microbe is driven from the host, or assumes a benign
relationship with the host
 Infection is the invasion or colonisation of the body
by pathogenic microorganisms
– Growing or multiplying within or on a host

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Infection and Disease
Disease
 What happens if the host loses the competition
for supremacy?
– Disease develops
 Disease:
– Refers to any change from the general state of good health

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Infection and Disease
 Disease occurs when an infection results in any
change from a state of health – physiological or
metabolic
– An abnormal state in which part or all of the body is not
properly adjusted or incapable of performing its normal
function
– An infectious disease occurs when this change is caused
by a microorganism or its products (e.g. toxins)
 The terms are not synonymous – a person may
be infected without suffering disease

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Host-Microbe relationship
 Microbes found on or in the human body
– Around 39 trillion (3.9 x 10 13 )
 Microbiota
– Reside in the body without causing disease
– Indigenous microbiota
 Permanent relationship with various parts of the body
– Transient microbiota
 Temporary and found only for limited periods of time
– Example: Escherichia coli and Candida albicans always found
in human colon, species of Streptococcus are transient