mcb lecture 3
DESCRIPTION
MCB lecture 3 topics: milestones on the history of MCB as a science, people significant in the development of MCB as a science, Koch's principles and exceptionsTRANSCRIPT
Quiz # 21. Complete the table: (10 points)
group of M.O. uni/multicellular
prokaryotic/ eukaryotic
specific name of study
(bonus, 0.20 points each)
2. Name the associated M.O. with the following conditions: gastric ulcer, diabetes, female infertility (3 points)
3. Differentiate between 1st Golden Age of MCB and 2nd Golden Age of MCB (2 points)
HISTORICAL OVERVIEW
OF MICROBIOLOGY
fossils of m.o. found in Australia date back to 3.5 BILLION years ago, whereas H. sapiens only appeared very recently
Infectious Diseases
studies of mummies and fossils:
syphilis, TB, schistosomiasis, tapeworm infection existed for as long as humans and animals existed
records of epidemics
•Egypt, 3100 BC, pestilence
•Thebes, Egypt, 1500 BC, epidemic fevers
•China, 1122, small pox
significant events in the science of MCB
1.development of microscope
2.use of scientific method
3.development of medical microbiology including the germ theory
4.development of modern microbiological techniques
diseases were cloaked in mystery
and regarded with superstition
1. development of microscope
Robert Hooke:
•studied great diversity of materials from plants
•first described the cellular structures of tree barks
•drew sketches and described “little structures” that seemed to be alive
microscopes
Anton Van Leeuwenhoek
•no formal training in science
•first person to see bacteria and protozoa
•“Father of MCB/ bacteriology/protozoology
•hobbyist, made more than 500 microscopes with up to 300x mag
permitted the awareness of widespread distribution of MO
examined scrapings from teeth, pond water, blood, sperm, diarrheal stool
•sent letters to Royal Society of London
•did not share his method for grinding or examining
“My method for seeing the very smallest animacules I do not impart to others; now how to see very many animacules at one time. This I keep to myself alone.”
modern day microscopes:
1000x magnification
but basic structure and function are not greatly different
2. use of scientific method
development of experimental system answered questions objectively (vs. superstition)
fall of superstition/ rise of MCB
Theory of Spontaneous Generation/ Abiogenesis
★living things arise from non- living things
★reinforced by observations of maggots coming out of meat, mushrooms growing on woods
★debated for 200 years
“animacules”
•considered to be early stages in development of more complex organisms
experiment by Francesco Redi
experiment by Louis Pasteur
Louis Pasteur
•French chemist
•contributions are foundations of MCB and cornerstone of modern medicine
significant events in the science of MCB
1.development of microscope
2.use of scientific method
3.development of medical microbiology including the germ theory
4.development of modern microbiological techniques
contributions1.disproved the spontaneous generation
2.discovered what occurs during alcoholic fermentation, and that different MO produce different products
• yeast: ethyl alcohol
• acetobacter: acetic acid
3.developed pasteurization
• 55 degrees centigrade for several minutes
• present times: 63- 65 for 30 minutes or 73- 75 for 15 seconds
contributions3. discovered the infectious agent that causes silkworm diseases and how to prevent such diseases
4. championed changes in hospital practices (along with Joseph Lister)
5. contributed to the germ theory of diseases, which states that specific MO cause specific diseases
ex: B. anthracis: anthrax
Dr. OLIVER HOLMES
• observe less infection in mothers giving birth in homes than in hospitals
Dr. IGNAZ SEMMELWEIS
• observed more infection in women examined immediately after doctors come out of autopsy rooms
• linked MO to diseases
3. development of medical microbiology including the germ theory
JOSEPH LISTER
• introduced aseptic technique for medical settings
ROBERT KOCH
• formulated the KOCH’S POSTULATES
3. development of medical microbiology including the germ theory
Koch’s Postulates
•a series of proofs that:
•verify the germ theory of diseases
•establish whether an organism was pathogenic
•establish the disease an organism causes
1. a particular M.O. must be present in all cases of the disease, and not present in healthy animals
2. M.O. must be isolated and grown pure
3. and 4. same disease must be produced when a healthy animal is inoculated with culture
5. same M.O. must be recovered from experimentally infected animal
KOCH’S Postulate
•stressed use of lab culture and identification of microorganisms
•R. Koch: invented inoculation, isolation, media, maintenance of pure cultures, and preparation of specimen
•Colleagues:
•R. J. Petri: invented flat glass disk in which to culture bacteria
•Frau Hess (wife of colleague): suggested use of agar (polysaccharide from seaweed)
4. development of modern microbiological techniques
exceptions to Koch’s Postulates
certain pathogens do not grow on artificial medium,ex: MO for syphilis, leprosy --obligate intracellular pathogens require living host cells, therefore propagate M. leprae in armadillos, Treponema pallidum for syphilis in testes of rabbitsmany pathogens are species-specific
some diseases are synergistic infections, caused by 2 or more M.O.. ex: acute necrotizing ulcerative gingivitis and bacterial vaginosissome pathogens become altered when grown in vitro, i.e. less or non-pathogenic
some diseases are not caused by MO