CHAPTER 1 WHAT IS MICROBIOLOGY AND WHY IS IT IMPORTANT?

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Feb 20, 2013 (3 years and 10 months ago)

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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science

CHAPTER 1

WHAT IS MICROBIOLOGY AND WHY IS
IT IMPORTANT?

© WHO / TDR / Crump

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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science

The Importance of
Microorganisms


medical and most populous group of
organisms and are found everywhere on
the planet


play a major role in recycling essential
elements


source of nutrients and some carry out
photosynthesis


benefit society by their production of food,
beverages, antibiotics and vitamins


causative agents of some important
diseases


What is Microbiology?


generally defined as the study of
organisms too small to be clearly seen by
the unaided eye (i.e.,

microorganisms
)


these organisms are relatively simple in
their construction and lack highly
differentiated cells and distinct tissues


Members of the Microbial World



procaryotic cells
lack a true membrane
-
delimited nucleus


eucaryotic cells
have a membrane
-
enclosed nucleus, are more complex
morphologically and are usually larger
than procaryotic cells

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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science

Procaryotes


most are single
-
celled


most have peptidoglycan in cell wall


can survive broad range of environments


most are non
-
pathogenic and play major
role in nutrient recycling

……..
Eucaryotes


animals, plants and
eucaryotic

microorganisms


microorganisms include
protists

(unicellular algae, protozoa, slime molds
and water molds) and fungi


most are larger than
procaryotic

cells


…….. Viruses


acellular


smallest of all microbes (smallest is 10,000
times smaller than a typical bacterium)

Importance of Microorganisms


first living organisms on planet


live almost everywhere life is possible


more numerous than any other kind of
organisms


global ecosystem depends on their
activities


influence human society in many ways

ISBN: 978
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6514
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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

WHY IS THIS IMPORTANT?


Microbiology is more relevant than ever in
today’s world.


Infectious diseases are a leading health
-
related
issue, especially in a society where the elderly
population is increasing.


New infectious diseases continue to emerge
and be identified all the time.


Microbiology impacts every facet of daily life

Discovery of Microbes

Antony Van Leeuwenhoek (1632
-
1723)


first person to observe and describe
microorganisms accurately


Developed early microscope


First to observe microbes:“animalcules



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Microbiology: A Clinical Approach,
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……..
Pasteur

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Microbiology: A Clinical Approach,
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……..
Pasteur




Pasteur laid the foundation of aseptic
techniques, techniques that prevent
contamination by unwanted microbes. These
techniques are based on Pasteur’s idea that
microbes can be killed by
heat

and that
procedures can be designed to inhibit the access
of airborne microbes to nutrient environment.




He disapprove the idea that microorganisms
spontaneously generated from non
-
living
matter.




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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

The Golden Age of Microbiology
(1857
-
1914)


Many disease producing organisms were
discovered


Microbial metabolism studies undertaken


Microbiological techniques refined


A better understanding of the role of
immunity and ways to control and prevent
infection by microbes

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Microbiology: A Clinical Approach,
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The Role of Microorganisms in Disease



was not immediately obvious



establishing connection depended on
development of techniques for studying
microbes



once established, led to study of host
defenses
-

immunology

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Microbiology: A Clinical Approach,
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© Garland Science

Recognition of the Relationship between
Microorganisms and Disease



Agostini

Bassi

(1773
-
1856):

showed that a disease of silkworms was caused by
a

fungus



M. J. Berkeley (ca. 1845):

demonstrated that the great
Potato Blight of
Ireland
was caused by a
water mold

Heinrich de Bary (1853):

showed that
smut and rust fungi
caused cereal
crop diseases

Louis Pasteur (
1860s
-

80s)
:

showed that the
p
ébrine

disease of silkworms
was caused by a protozoan

Aseptic techniques


……..
Pure Culture Technique


Phases of antibiotic development



Pre Antibiotic Era
-
No antibiotic


Antibiotic era
-

penicillin


“New” Diseases


Resurgence of “old” diseases


Microbial resistance to drugs


Emergent Diseases and the

Post
-
Antibiotic Era



Experts agree that decades of antibiotic use and
abuse have contributed to the emergence of antibiotic
-
resistant organisms in both hospital and community
settings.



Antibiotic era


We have all heard of the
Pre
-
Antibiotic Era
, prior to the
1940’s when millions of people died from common
bacterial infections because antibiotics were not used to
treat them.



In the last 50 years we have enjoyed the luxury of
knowing that bacterial infections can almost always be
cured by using antibiotics. We are now in the
Antibiotic
Era.

Post
-
Antibiotic Era


As we enter the 21
st

Century, we are gradually slipping
into the Post
-
Antibiotic Era, a time when antibiotics no
longer work because bacteria have become
resistant

to
all the antibiotics.


The change will not come as suddenly as the start of the
Antibiotic Era, because the change to antibiotic resistant
germs has been slow, up until now.


New strains are rapidly developing



In the next 5
-
10 years we will start noticing the change
much more dramatically.

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Microbiology: A Clinical Approach,
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Microbiology: A Clinical Approach
© Garland Science

OVERVIEW

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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science

CASE STUDIES FROM DAILY LIFE


The following case studies illustrate how
microbiology is part of our everyday lives: (
Ref. pg3
-
7)


Special Delivery


Ivan Goes to Chicago


Hamburger Havoc


The Hospital Can Be Dangerous


Did You Wash Your Hands


Mary, Mary, Quite Contrary


It’s For the Birds


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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

ISBN: 978
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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

MICROBIOLOGY & INFECTIOUS
DISEASE


Today microbiology is mentioned frequently in
the news.


It affects many facets of our daily lives,
including:


The air we breathe


The food we eat


The hospitals where we go for treatment of illness
and injury


The natural disasters which sometimes occur
without warning


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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science

THE RELEVANCE OF MICROBIOLOGY
TO HEALTH CARE


There has always been disease.


For generations, little could be done to treat or
prevent disease.


Advances in public health awareness lessened the
effects of infection.


Infectious disease utilizes a large percentage of
health care.


Health care professionals need to understand how
pathogens cause disease.

ISBN: 978
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8153
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6514
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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

…THE RELEVANCE OF MICROBIOLOGY
TO HEALTH CARE


The discovery of antibiotics began to prevent
serious infection.


Vaccination and better sanitation practices
reduced the incidence of infectious diseases.


For a time, most infectious diseases were
thought to be under control.

ISBN: 978
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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

…THE RELEVANCE OF MICROBIOLOGY
TO HEALTH CARE


Diseases once thought to be under control are
reappearing


Pathogens are showing increasing resistance to
antibiotics.


New diseases are emerging and organisms that were
thought to be harmless have been discovered to cause
disease in certain circumstances.


Interest in bioterrorism has progressed from fiction to
fact.


A fundamental understanding of microbiology has
never been more relevant.

ISBN: 978
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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science

INFECTIOUS DISEASE


Only a tiny fraction of microorganisms cause
infections.


A microorganism that causes an infection is
called a pathogen.


Only a fraction of pathogens affect humans.

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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

…INFECTIOUS DISEASE


The potential of a pathogen to cause disease is
referred to as its degree of virulence.


Pathogens can be categorized based on their
degree of virulence.


Many bacteria and some fungi are part of the
normal microbial flora of the body.


They naturally colonize the skin and mucosal surfaces.


Most of the time, these organisms are completely
harmless.

ISBN: 978
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6514
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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

…INFECTIOUS DISEASE


Some of these organisms provide important
products and services to the body.


Under certain circumstances, these organisms
become pathogenic.


When this happens, the organisms are called
opportunistic pathogens and typically possess
a mild degree of virulence.

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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

...INFECTIOUS DISEASE


Some pathogens are always highly virulent.


Highly virulent pathogens are always
associated with disease.


Most pathogens can be looked at from the
following 3 perspectives:


Epidemiology


Pathogenesis


Host
defense

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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

EPIDEMIOLOGY


Epidemiology is the study of factors determining
the frequency and distribution of disease.


In epidemiology, pathogens are studied by how
well they meet the five requirements of infection:


Entry (Get in)


Establishment (Stay in)


Defeat the host
defense


Damage the host


Be transmissible

ISBN: 978
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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

...EPIDEMIOLOGY


In epidemiology, pathogens are classified by the
transmission mechanisms they use. Such as:


Air


Food or water


Insect vectors


Person
-
to
-
person contact


Pathogens can also be classified according to their
geographic distribution


Some are found worldwide, others are restricted to
certain geographic areas.

ISBN: 978
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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science

...EPIDEMIOLOGY



Providing the best care for infected individuals
and protection of others involves a clear
understanding of the 5 requirements for infection.


Knowing how an organism gains entry and how it
spreads are vital to care for infected individuals


It allows for the implementation of strategies to limit
spread.


It also helps in understanding of the spread of disease.

ISBN: 978
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8153
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6514
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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

...EPIDEMIOLOGY



Epidemics are caused by a variety of factors,
including the following:


Poor socioeconomic conditions


Ignorance of how infections occur


Poor hygiene


Natural disasters

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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science

PATHOGENESIS


Virulence factors are required for a pathogen
to do the following:


Persist in the patient


Cause disease


Escape or defeat host defenses

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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science

...PATHOGENESIS


Pathogens employ a variety of methods to
accomplish infection.


Bacterial pathogens can:


Produce digestive enzymes


Produce toxins


Viral pathogens can kill the host cells.


Sometimes, damage associated with an
infection is due to over active host defenses.

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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science


PATHOGENESIS



Symptoms can be associated with particular
types of infection:


Coughing


respiratory infection


Diarrhea


digestive infection


Nervous system dysfunction


central nervous
system

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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science

HOST DEFENSE


Infection is a complex and competitive
struggle.


It can be characterized as pathogens versus
host defense.


The outcome of this struggle depends on the
success or failure of the host defense.


Failure of the host defense = infection!

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6514
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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

....HOST DEFENSE


Many pathogens have developed methods to
defeat host defenses.


Some directly attack host defenses


Some change their looks (a form of camouflage)


Some hide

ISBN: 978
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8153
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6514
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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

TREATMENT OF INFECTIOUS DISEASES


Many potent and successful tools are available
to defeat infection. These include:


Antibiotics


Disinfectants and antiseptics


Antibiotics are toxic chemicals and therefore
must act selectively.


They must kill the disease
-
causing microorganisms
but not harm the patient.

ISBN: 978
-
0
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8153
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6514
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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

…TREATMENT OF INFECTIOUS
DISEASES


Treatments are easier for bacterial infections
than for fungal and viral diseases.


Fungal cells are very similar to human cells so
very few chemicals are selectively toxic.


Viruses are intracellular parasites so either:


They must be attacked before entry into a host cell.

or


The infected host cells must be killed to kill the
virus.

ISBN: 978
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8153
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6514
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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science

…TREATMENT OF INFECTIOUS
DISEASES


The best treatment of disease is prevention.


Prevention involves public health measures
and immunization.

ISBN: 978
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8153
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6514
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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

…TREATMENT OF INFECTIOUS
DISEASES


Public health measures include:


Disinfection of water supplies


Monitoring food supplies


Proper hygiene and sanitation


Proper waste removal and treatment


Insect and pest control

ISBN: 978
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8153
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6514
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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

..TREATMENT OF INFECTIOUS
DISEASES


Immunization requires that we understand
immune mechanisms and that we design
vaccines that will successfully stimulate
protection.


Immunization also requires:


Public health control of the immunization of
children


Design and development of new vaccines


An ability to ensure the safety of vaccines

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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science

MICROBIOLOGY ISN’T JUST ABOUT
INFECTIOUS DISEASE


Some microbes are very beneficial to humans
as they are able to:


Recycle vital elements in soil.


Convert elements in the environment into usable
forms.


Return CO
2
into the atmosphere.

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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science

BIOREMEDIATION AND RECYCLING


Microbes have been routinely used for
bioremediation since 1988.


Microbes can be used:


To recycle waste water during sewage treatment.


To clean up and decontaminate toxic waste
including chemical and oil spills.


In the production of enzymes that are subsequently
used in cleaning solutions.

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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science

INSECT CONTROL


Bacteria are extensively used to control pests.


They can be applied as part of crop dusting.


Bacterial genes can be engineered into the plants
themselves.


Using bacteria in these ways is seen as being
safer than using chemicals.

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Microbiology: A Clinical Approach,
by Tony
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© Garland Science

Microbiology: A Clinical Approach
© Garland Science

BIOTECHNOLOGY


Bacteria and viruses are often used for many
new technologies.


Bacteria can be engineered to produce drugs.


Viruses can be used for gene therapy strategies.

ISBN: 978
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8153
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6514
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Microbiology: A Clinical Approach,
by Tony
Srelkauskas

© Garland Science

Microbiology: A Clinical Approach
© Garland Science

Bibliography



Microbiology, A clinical Approach
-
Danielle Moszyk
-
Strelkauskas
-
Garland Science 2010


http://en.wikipedia.org/wiki/Scientific_method


http://www.brighthub.com/science/medical/articles/21169.aspx

(
L Pasteur & theory of Biogenesis)