História da Microbiologia

Question 1

Antoni van Leeuwenhoek

Answer 1

(1632–1723)

first to describe Bacteria

(observed in dental plaque, drawn in one of his letters to the Royal Society of London 1684)

Question 2

Louis Pasteur

Answer 2

(1822–1895)

Discovered that alcoholic fermentation was a biologically mediated process (originally thought to be purely chemical)

Disproved theory of spontaneous generation

Led to the development of methods for controlling the growth of microorganisms (aseptic technique and Pasteurization)

Developed vaccines for anthrax, fowl cholera, and rabies

Question 3

Pasteur disproved theory of spontaneous Generation

Answer 3

Nonsterile liq poured into flask –> Neck of flask drawn out in flame –> Liq sterilised by extensive heating
–> a) liq cooled slowly; dust and microorgs trapped in bend -long time-> liq remains sterile indefinitely (w/ open end!)

–> b) flask tipped such that microorg-laden dust contacts sterile liq -short time-> liq putrefies

Question 4

Robert Koch

Answer 4

(1843–1910) PN Med 1905

Demonstrated the link between microbes and infectious diseases –> Identified causative agents of anthrax and tuberculosis (Bacillus anthracis and Mycobacterium tuberculosis)

Koch’s postulates

Developed techniques (solid media) for obtaining pure cultures of microbes, some still in existence today:

• Discovered: solid media–> simple way to obtain pure cultures
• potato slices –> uniform and reproducible nutrient solutions solidified with gelatin and agar
• Observed that masses of cells (= colonies) have different shapes, colors, and sizes

Question 5

Koch’s Postulates

Answer 5

1. suspected pathogen must be present in all cases of the disease and absent from healthy animals (Observe blood/tissue under the microscope)
2. suspected pathogen must be grown in pure culture (Streak agar plate with sample from either diseased or healthy animal)
3. Cells from pure culture of suspected pathogen must cause disease in a healthy animal (inoculate healthy animal with cells of suspected pathogen)
4. . suspected pathogen must be reisolated and shown to be the same as the original (Remove blood or tissue sample and observe by microscopy)

Question 6

Molecular Koch’s postulates

Answer 6

• potential role of genes and their products in infection and disease
• phenotype or property under investigation should be associated with pathogenic members of a genus or pathogenic strains of a species.
• Specific inactivation or deletion of the gene(s) associated with the suspected virulence trait should lead to loss of pathogenicity or virulence.
• replacement of the modified gene(s) for its allelic counterpart in the strain of origin should lead to restoration of pathogenicity.

Question 7

Shift Causes of Death

Answer 7

1900:
1- influenza and pneumonia (I)
2- tuberculosis (I)
3- Gastroenteritis (I) 
... 5/10 I 

Today:
1- heart disease (N)
2- cancer (N)
… 2,5/10 I