The Value of Microbiology
Chapter 1
Objectives
• Define microbiology
• Describe significant contributions to the
science
• List other areas of study in microbiology
• Identify basic health care procedure used
to prevent and control disease
Microbiology
• Began about 100 years ago
• Micro = small, bio = life, logy = the study of
• Microbes = tiny organisms that can only be
seen through a microscope (instrument with
magnifying lens)
Microbiology
• Includes the study of all microbes
– Bacteria (microscopic, unicellular organisms)
– Fungi (microscopic plant life lacking chlorophyll)
– Parasites (organisms that live on another living organism at
whose expense it obtains some advantage)
– Viruses (submicroscopic infectious organisms)
History of Microbiology
• Anton van Leeuwenhoek (1632-1723)
– Invented first, simple microscope by grinding
a single lens
History of Microbiology
• 1650 – 1850: Spontaneous generation or
abiogensis was most widely accepted for
the explanation of microbes
– Life can suddenly or spontaneously arise from
decomposing nonliving matter
History of Microbiology
• Lazzaro Spallanzani (1729 – 1799)
– Conducted experiments to disprove
abiogenesis.
Turbid = cloudy
Animalcules = microbes
History of Microbiology
• Edward Jenner (1749- 1823)
First experimented
with cowpox as a way
to prevent smallpox
History of Microbiology
• Louis Pasteur (1822-1895)
• French biochemist (scientist
specializing in the chemical reactions)
• Conducted several
experiments to prove
biogenesis (life comes from preexisting
life)
• Developed the germ theory of
fermentation (belief that living organisms
cause disease)
History of Microbiology
• Pasteur described the process of
fermentation (the decomposition of a carbohydrate in the
absence of oxygen)
• Developed pasteurization (heating to destroy
pathogenic bacteria in beer and wine and later used also for milk)
• Developed specific vaccines from
attenuated (weakened) pathogens
History of Microbiology
• Ignaz Philipp Semmelweis (1818-1865)
– Noted that illness could be spread to other patients by
the treating physicians
History of Microbiology
Contagious – capable of being transmitted from
one person to another
Post mortem – autopsy performed on the
deceased in order to determine the cause of
death
Hypothesis – educated guess based on
reasonable experimentation
Puerperal fever – infection resulting from an
infection originating in the birth canal and
spreading throughout the body
History of Microbiology
• Labile – chemically unstable, susceptible to heat
• Endospore – spore formed within the parent cell
• Sepsis – systemic disease associated with the presence of
pathogenic microorganisms in the blood
• Disinfection – process of killing pathogenic organisms by
chemical or physical means
• Antiseptic – a chemical compound that can inhibit or stop the
growth of bacteria without necessarily killing them
• Aseptic – exclusion of the presence of infectious pathogens
History of Microbiology
• Lord Joseph Lister (1827-1912)
• Prevented the growth of
microorganisms by using
carbolic acid in the washing
or disinfection of hands and
surgical tools
History of Microbiology
• Robert Koch (1843-1910)
• Developed an elaborate
technique of isolating and
identifying specific
pathogens (disease causing
microorganisms)
History of Microbiology
Koch’s Postulates:
•The bacteria must be present in every case of the
disease.
•The bacteria must be isolated from the host with the
disease and grown in pure culture.
•The specific disease must be reproduced when a
pure culture of the bacteria is inoculated into a
healthy susceptible host.
•The bacteria must be recoverable from the
experimentally infected host
• Immunology – study of the structure and
function of the immune system
• Intradermal – under the skin
• Botanist – a scientist who specializes in
the study of plants
• Virologist – scientist specializing in the
study of viruses and diseases they cause
• Bacteriophages – a virus that infects
bacterial cells, sometimes lysing (or killing)
the cell
• Feline – pertaining to cats
• Pericarditis – inflammation around the
heart
• Emerging pathogens – microorganisms
once not considered to be pathogenic, but
are now found to be infectious
• Saprophytic – organism that obtains its
nutrition from dead or decaying matter
Other Areas of Microbiology
• Aquatic Microbiology – study of
microorganisms found in marine and fresh
water
• Agricultural Microbiology - study of
microorganisms found in dairy and food
• Environmental Microbiology –
microorganisms found in air, soil, sewage,
and water
Other Areas of Microbiology
• Industrial Microbiology – study of using
microorganisms to produce essential
products (alcohol, beer, wine, antibiotics,
enzymes, organic acids, medicines,
vitamins)
• Exobiology – studies the possibility of
microorganisms in outer space and on
other planetary bodies
Areas of Microbiology
• Medical Microbiology
– Study of bacteria, viruses, fungi, parasites,
and other microorganisms that may cause
disease
• Epidemiology – study of factors
surrounding spread, frequency , and
distribution of diseases, injury, and other
health related events
• Virulence – degree of pathogenicity or
disease producing ability of an organism
• Mutagenic – a change in the genetic
structure of an organism
• Prognosis – forecast of possible outcome
of a disease
Preventing Infection
• Majority of microorganisms are harmless
• Responsibility of every health care worker
to follow safety precautions
– Proper hand washing
– Changing bed linen
– Sterilizing equipment