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Microbiology

Microbiology


The study of organisms too small to be seen
without magnification.


Bacteria


Viruses


Fungi


Protozoa


Helminths (worms)


algae

Branches of study within
microbiology


Immunology


Public health microbiology & epidemiology


Food, dairy and aquatic microbiology


Biotechnology


Genetic engineering & recombinant DNA
technology

Microbes are involved in


Nutrient production & energy flow


Decomposition


Production of foods, drugs & vaccines


Bioremediation


Causing disease

Impact of pathogens


Nearly 2,000 different microbes cause
diseases.


10 billion infections/year worldwide.


13 million deaths from infections/year
worldwide.


7
Characteristics of microbes

8

9
Antonie van Leeuwenhoek

First to observe living
microbes

his single
-
lens
magnified up to 300X
(1632
-
1723)

10

Spontaneous generation
Early belief that some forms of life
could arise from vital forces present in
nonliving or decomposing matter.
(flies from manure, etc)

14
Louis Pasteur

Showed microbes caused
fermentation & spoilage

Disproved spontaneous
generation of m.o.

Developed aseptic
techniques.

Developed a rabies vaccine.
(1822
-
1895)

Germ theory of disease
Many diseases are caused by the growth
of microbes in the body and not by sins,
bad character, or poverty, etc.

16
Robert Koch

Established a sequence of
experimental steps to
show that a specific m.o.
causes a particular
disease.

Developed pure culture
methods.

Identified cause of
anthrax, TB, & cholera.
(1843
-
1910)

18
3 domains

Eubacteria
-
true bacteria, peptidoglycan

Archaea

odd bacteria that live in extreme
environments, high salt, heat, etc

Eukarya
-
have a nucleus, & organelles

17
Taxonomy
-
system for organizing,
classifying & naming living things

Domain
-
Archaea, Bacteria &
Eukarya

Kingdom
-
5

Phylum or Division

Class

Order

Family

Genus

species

20
Naming micoorganisms

Binomial (scientific) nomenclature

Gives each microbe 2 names

Genus
-
noun, always capitalized

species
-
adjective, lowercase

Both italicized or underlined

Staphylococcus aureus (S. aureus)

Bacillus
subtilis
(B. subtilis)

Escherichia coli
(E. coli)

28
Epidemiology

The study of the frequency and distribution of
disease & health
-
related factors in human
populations

Surveillance

collecting, analyzing, & reporting
data on rates of occurrence, mortality, morbidity
and transmission of infections

Reportable, notifiable diseases must be reported to
authorities
Communicable disease


can be spread.

Noncommunicable


cannot be spread from one
person to another.


Black Plague killed 200

million

Small pox killed 1/3 of

Europe in 1348.


29

Centers for Disease Control and Prevention
(CDC) in Atlanta, GA

principal
government agency responsible for keeping
track of infectious diseases nationwide

http://www.cdc.gov

30

Prevalence

total number of existing cases
with respect to the entire population usually
represented by a percentage of the
population

Incidence

measures the number of new
cases over a certain time period, as
compared with the general healthy
population

31

Mortality rate

the total number of deaths
in a population due to a certain disease

Morbidity rate

number of people afflicted
with a certain disease

32

Endemic

disease that exhibits a relatively
steady frequency over a long period of time
in a particular geographic locale

Sporadic

when occasional cases are
reported at irregular intervals

Epidemic

when prevalence of a disease is
increasing beyond what is expected

Pandemic

epidemic across continents
Reservoirs of Infection


Primary habitat in the natural world of a
pathogen.


Living reservoirs may or may not have
symptoms.


Vectors


living animal that transmits
infectious disease.


Nonliving reservoirs


soil, water


36
Vectors

37
Patterns of transmission

Direct contact

Indirect contact

Vehicle

inanimate material, food, water,
biological products, fomites

Airborne

droplet nuclei, aerosols

38

39
Nosocomial infections

Diseases that are acquired during a hospital
stay

Most commonly involve urinary tract,
respiratory tract, & surgical incisions

Most common organisms involved gram
-
negative intestinal flora,
E. coli,
Pseudomonas, Staphylococcus

41
Koch’s postulates
1.
Find evidence of a particular microbe in every
case of a disease
2.
Isolate that microbe from an infected subject and
cultivate it artificially in the laboratory
3.
Inoculate a susceptible healthy subject with the
laboratory isolate and observe the resultant
disease
4.
Reisolate the agent from this subject
Bacteria


Binary Fission


Reproduction


One cell grows to about double its original
size and then splits.


Dna replicates


divides

Shapes of Bacteria

Coccus


spherical or oval shaped.


-
diplococcus: cocci in pairs


-
streptococcus: cocci in chains


-
tetrad: arranged in squares of 4


-
sarcina: arranged in cubes of 8


-
staphylococcus: random planes


diplococcus


streptococcus


Tetrad


sarcina


staphylococcus


Bacillus


Rod
-
shaped bacteria

Bacillus


Bacillus under scanning electron
microscope


Escherichia coli


Spiral


3 forms: vibrio, spirillum, spirochete

Vibrio cholerae


Spirillum


Spirochete


Identifying Bacteria


Gram Positive


Gram Negative


Shape

Gram
-
Positive


After being stained appears purple.


Due to a peptidoglycan wall.


Thicker wall


Gram
-
negative


Appears red when gram stained.


Picks up safranin stain.


Thin wall.


How they use oxygen?

Facultative

anaerobe

-

Prefer to
grow in the presence of oxygen,
but can grow in an anaerobic
environment using fermentation.


Strict Aerobe


Cannot survive in the absence of oxygen.

Strict Anaerobe


Generate energy by fermentation and are
killed in the presence of oxygen.


Thioglycollate agar


determines the oxygen relationship of a
microorganisms.


Contains: thioglycollic acid, cystine and
0.35% agar.


The thioglycollic acid and agar prevent
oxygen from entering the entire medium.

Autoclave


Pressurized device designed to elevate
temperature and pressure to sterilize
material and solutions.

Media


Liquid media


Semi
-
solid media


Solid media

Semi
-
solid media


Can be used for motility testing.

Solid Media


Contains more agar = where microbes grow.


This enables the formation of colonies.

Different Media


Grows all: Some agar grows everything.


Differential media: Some shows different
reactions.


Selective media: Some can grow certain
bacteria.

MacConkey Agar


Differential media.


Detects lactose fermentation.

Viewing Microbes


Resolution(seeing detail) can be increased
using immersion oil.


Allows the light ray to go directly through
the objective lens.

Gram Stain


Fix microbe onto slide.


20 secs. Crystal Violet


Rinse with water


15 secs. Iodine


Rinse with water


Alcohol rinse


20 secs. Safranin


Rinse with water