Dental Pathology and Microbiology Unit 1 Classifications of
Microorganisms
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Unit 1 Definition: Microbiology Micro Bio Ology Oldest form of
life Most are Beneficial Only a few are harmful
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Why do we study Microbiology? The world we live in.. People
live longer Diseases are now controlled Healthier Food Better
conditions Medical Advances Environmental advances
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Microbiology & Medicine Science MUST be ready to face the
challenge Knowledge of transfer of microorganisms can reduce spread
of disease Knowledge of immunity can reduce disease Knowledge of
sterilization & disinfection procedures will reduce or prevent
spread of disease Not all microorganisms are harmful, some are even
helpful
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Theory of Spontaneous Generation Mold on food Spoiled drinks
& spoiled food Theory was = caused by devil or curse of God
Seemed to be no physical cause Some scientists attempted to
disprove theory Catching diseases spread by contact with humans and
animals
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Leeuwenhoek Dutch merchant & Amateur scientist Hobby of
grinding lenses to observe microbes Animalcules = small moving
objects Drew pictures and wrote volumes Early lenses led to early
microscopes Took scrapings from teeth to observe appearance
Referred to as Father of Microbiology
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Pasteur Professor of chemistry in France Experimented with
heating liquid Process of pasteurization Process used for wine,
beer & Milk Food canning process Discovery labeled Germ Theory
of Disease proved that airborne bacteria was the cause of some
diseases
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Golden Age of Microbiology Many new discoveries 1880-1910
Communication was limited Scientists and doctors in all countries
were working on theories Numerous causes of disease & death;
patients died in hospitals; women died in childbirth Physicians
wore street clothes in surgery
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Holmes Physician in Boston Studied child bed fever in new
mothers Suggested nurses and physicians wash hands
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Semmelweis Hungarian doctor Explored use of antiseptics with
washing Number of deaths were reduced Both Holmes & Semmelweis
were working on same experiments in different countries
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Lister English Surgeon Set out to prove that wound infection
due to microbes Tried carbolic acid (PHENOL) Soaked surgical
dressings & instruments & tables Asked staff to use phenol
on hands after washing Established aseptic techniques
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Koch German biologist & physican Proved specific bacteria
causes disease Developed rules 1. Organism must be present 2.
Organism must be isolated 3. Organism must produce disease in
another 4. Organism must be recovered
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Miller American dentist & researcher Theory: connection
between bacteria, carbohydrates & tooth disease BACTERIA + FOOD
= Produce Acids Acids on teeth = cause decay (cavities)
Normal Flora Resident microbial population of human body
Microorganisms live (reside) in and on body *Always present
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Activities of Microbes Bacteria in soil converted to usable
nutrients Bacteria cultured to make vinegar, vitamins, antibiotics
Bacteria or fungi used to pickle cucumbers; Produce cultured dairy:
yogurt & sour cream Yeast makes bread dough & used in beer
production
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GROUPS OF MICROORGANISMS BACTERIA VIRUSES FUNGI Yeasts &
Molds PROTOZOA Bacteria & viruses are concern in dental office
Some fungi can cause dental problems
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BACTERIA Small cells Divide by binary fission SHAPES: COCCI
BACILLI SPiRILLA VIBRIOS
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Bacteria Grow in COLONIES Bacterial growth = increase in cell
numbers Cells divide by BINARY FISSION Division of cells occurs
every 20-30 minutes Some bacteria have ability to grow Some
bacteria do not survive
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Growth Requirements of Bacteria Temperature Acidity Nutrients
Oxygen Metabolism Water
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Bacteria Culturing Bacteria grow bacteria in laboratory
Nutrient base called medium Preventing growth changing requirements
Bacteriostatic Bacteriocidal
FUNGI: Yeasts & Molds Larger than bacteria Disease:
Candidiasis (known as thrush) Found inside mouth Cannot be killed
with antibiotics Usually cause problems after use of too much
antibiotics
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Candidiasis/Yeast/Thrush
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Baby thrush
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VIRUS Smaller than bacteria Have many shapes Cause disease by
changing cells Cannot be killed with antibiotics Some antiviral
drugs Best approach is immunization or Infection Control
Procedures
VIRAL NO PPE??? Herpetic conjunctivitis- Herpes of eye Herpetic
Whitlow- Herpes on hand
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Protozoa Rickettsiae Live in bloodstream, mouth & digestive
tract Contaminated drinking water Gum disease (Periodontal disease)
Parasites cannot live outside a host Diseases are Typhus &
Rocky mountain fever
