Lecture 1: Intro To Microbiology Flashcards
What is microbiology?
The study of living organisms.
How many organisms are harmless? Provide a percentage value.
Most organisms are harmless (87%).
Many organisms are helpful. How so?
They have an important role in the food chain e.g. Decomposition & nitrogen fixation
A) what percentage of organisms are opportunistic?
B) Explain what opportunistic means using an example.
C) give examples of such organisms.
A) 10%
B) Microbes that are usually harmless but become pathogenic when placed in different conditions.
C) E.g. Bowel flora that find their way into bladder can become pathogenic.
A) How many percent of organisms are overtly pathogenic.
B) explain what overtly pathogenic means.
C) give examples of such organisms.
A) 3%
B) organism that usually cause disease when they are present on or in the human body, including upon contact with, an otherwise healthy person.
C) syphilis, tapeworm, tuberculosis and anthrax
What is normal flora?
The microbes that naturally inhabit surfaces of the human body.
What is the the total microbial load?
> 1013 microbial cells in the body vs 1013 body cells.
How is it possible to have such a large total microbial load? (More microbes than blood cells in body).
These organisms occur at sites exposed to, or that communicate with the external environment e.g. skin, nasal passages, mouth, throat, urogenital tract and intestinal tract.
What structures of the body are sterile?
Blood, tissues & lower respiratory tract are regarded as sterile.
Where in the body is most of the normal flora found?
Most of the normal flora are found in the large intestine.
What is most of the faecal mass composed of?
Most of the faecal mass is bacteria (40-60%) and water: Importance of toilet/handwashing!!!!
Name a common bowel/ faecal flora.
Escherichia coli
Does normal flora play a beneficial or harmful role in maintaining health?
Beneficial role.
Give example of when microbes are used in food and drug industry.
- YEAST: wine, beer, bread
- FUNGI: cheese, antibiotics
- BACTERIA: yoghurt, antibiotics, sauerkraut, vinegar
What has the study of infectious disease-causing microbes led to an understanding of?
- Personal/community hygiene: ⬆ hand washing, ⬆ waste treatment/sanitation practices= ⬇ disease
- Microbial virulence and disease severity: ⬆ virulence of an organism = ⬆ severity
- Prevention and control measures of microbial disease transmission: Antimicrobial therapy/treatment of infection, Disinfection & Sterilisation
- Food processing and canning techniques: hygiene, cooking, pasteurisation
- Industrial microbiology e.g. brewing/baking plus chemicals like acetone
- Environmental e.g. bioleaching
Who was the 1st person to describe a cell?
They even wrote the first book detailing observations with a microscope.
Robert Hooke
This person experimented with dressings soaked in carbolic acid (used as an antiseptic) and was credited for developing antisepsis for surgery.
Joseph Lister
What was Antoni van Leeuwenhoek’s contribution to microbiology?
- Further developed the microscope (one with a movable stage)
- First to describe bacteria including their shapes
- Reported existence of protozoa in 1674 and bacteria 1676
- Why did it take two years to discover bacteria? bacteria is SMALLER
- Very secretive: did not let anyone see microscopes (not even his family or the Tsar of Russia)
- Microscopy lost for 100 years after his death
What was Ignaz Semmelweis’s (Adrian’s favourite guy) contribution to microbiology?
- First to use handwashing in clinical practice
- however Physicians refused to wash hands
- Hand washing only accepted years later after work by Pasteur, Lister, Koch
What was Louis Pasteur’s contributions to microbiology?
- Germ theory of fermentation
- Disproved theory of spontaneous generation (Abiogenesis) (disapproved the thought that you got sick because you were cursed- took misfortune out of disease).
- Discovered pasteurisation (originally used to prevent spoilage of wine)
- Aseptic techniques and sterilisation
- Developed culture methods
- Took credit for the first anthrax vaccine using Henri Toussaint’s method
Who discovered the germ theory of disease? And what other contributions did this person make in microbiology?
- Robert Koch
- First to study Anthrax and Tuberculosis
- Discovered the causative organism of cholera (Vibrio cholerae)
- Found that microorganisms can invade other organisms and cause disease- this is the bases of Koch’s postulates which is the germ theory of disease
- Devised solid media for culturing bacteria
- Contributed to developing staining methods for microbes
Explain the four points of Koch’s Postulates (Germ Theory Disease).
- The specific causative agent must be found in every case of an infectious disease
- The disease organism must be isolated in pure culture
- Inoculation of a sample of culture into a healthy, susceptible animal must produce same disease
- The disease organism must be recovered from the infected animal
• Summary: A specific infectious disease is caused by a specific microbe
What were the limitations to Koch’s theory?
- Works with many bacteria (remember Koch was working with anthrax which is Bacillus anthracis, a bacteria)
- Doesn’t work with viruses or intracellular bacteria (cannot isolate these in pure culture)
- Doesn’t work with human only pathogens (e.g. HIV only affects humans and there is no animal model of disease)
- Obviously does not apply to non-infectious disease e.g. diabetes
Name the three domains classification of life.
Eubacteria (same as bacteria), archaea & eucarya.
