Chapter 1- Nbs

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Historical Introduction

Medical MicrobiologyDr.N.Bharathi Santhose MBBS., MD( Micro).,



What is Microbiology?

• Micro - too small to be seen with the naked eye• Bio - life

• ology - study of

Microbiology – Science about small living things

• The morphology and structures• Physiology• Pathogenesis and Immunology (medical microbiology)• Diagnosis,Treatment and prevention (medical microbiology)



Organisms included in the study

of Microbiology1. Bacteria2. Parasites

3. Yeasts and MoldsFungi

4. Viruses

BacteriologyParasitology

Mycology

Virology



Organisms Related To Medical

Microbiology• Acellular microbes

– Viruses

• Prokaryotic microbes – Bacteria

Eubacteria ChlamydiaSpirochetes Rickettsiae

Mycoplasma Actinomycetes

• Eukaryotic microbes – Fungi & Parasites





Anton van Leeuwenhoek (1632-1723)

In 1674 -1st person to actually see living microorganisms“wee animalcules ”



Robert Hook -1678

Developed compound microscope & confirmed



Spontaneous Generation

• Theory that life just“spontaneously”developed from non-livingmatter

• Example: – toads, snakes and mice -

moist soil – flies and maggots - manure

and decaying flesh



Spallanzani -1769

Opposed spontaneous generation theory- Organic contents supported the microbial growth

when exposed to air



Experiments to disprove Spontaneous Generation

• Francesco Redi 1668

• Rudolph Virchow 1858Theory of Biogenesis - Cells can only arisefrom preexisting cells

• Louis Pasteur 1861





Louis Pasteur (1822-1895)

• French chemist• Interest in fermentation

experiments• Established that

fermentation was caused by microbial agents

• Father of Microbiology



Important contributions

• Microbial theory of fermentation• Proved that life including microorganisms arise

from their like not spontaneously• Principles & Practices of sterilization• Development of initial bacteriological techniques

& methods

• Principle of Attenuation of Micro organism• Developed vaccine against chicken cholera,

Anthrax & Rabies.



Germ theory of Diseases

1867 -Father of Antiseptic Surgery1846 – discovered importance of sterilityin medical o erations



Robert Koch (1843-1910)

• German Physician• Father of Bacteriology

• Microbial Etiology ofInfectious Disease• Established “scientific rules”

to show a cause and effectrelationship between amicrobe and a disease -Koch s Postulates



Important Contributions

• Perfected Bacteriological Techniques• Introduced methods for isolation of pure strains of

bacteria• Introduced staining techniques for visualization of

microorganisms• Discovery & use of solid medium in Bacteriology• Discovery of causative agents of Tuberculosis,

Anthrax & Cholera• Use of laboratory animals for Experimental

Infections



Koch s Postulates 1. The same organisms must be found in all

cases of a given disease.2. The organism must be isolated and grown

in pure culture.

3. The isolated organism must reproduce thesame disease when inoculated into a healthysusceptible animal.

4. The original organism must again bere-isolated from the experimentally infectedanimal.



Exceptions to Koch s Postulates

Treponema pallidum (syphilis)Mycobacterium leprae (leprosy)



Paul Ehrlich (1854 -1915)

• German Scientist• Father of Chemotherapy

• Discovered „salvarsan -as achemotherapeutic agent forsyphilis

• Opened the new branch ofmedicine “ chemotherapy”



Important Contribution

• Refined the science of staining the organism• Identified that mycobacteria have acid fastness

nature• Proposed the theory for antibody production –

Side chain theory• Introduced methods of standardizing toxin and

antitoxin



Discovery of Virus

• By the end of 19 th century existence ofultra microscopic microbes was

proved

• Dimitri Iwanovski (1892) – a Russian chemist – Father of Virology

• Martinus Beijerinck ( DutchMicrobiologist) confirmed

• Walter Reed, USA (1902) – Yellow fever virus – Ist human disease of viral origin

Tobacco mosaic disease, caused by thetobacco mosaic virus



Contd..

• Good Pasture (1930 )developed techniques forviral cultivation in chick embryo

• Ruska (1934) introduced Electron Microscope• Enders (1940) developed Tissue culture

techniques for viral isolation





Classification by structure

– Subcellular – DNA or RNA surrounded by a protein coat – viruses

– Prokaryotic – simple cell structure with nonucleus or organelles – bacteria

– Eukaryotic – complex cell structure withnucleus and specialized organelles –

protozoans, fungi, parasites



Differences…..



Prokaryote cells

• capsule : slimy outer coating• cell wall : tougher middle layer

• cell membrane : delicate inner skin• cytoplasm : inner liquid filling• DNA in one big loop• pilli : for sticking to things

• flagella : for swimming• ribosomes : for building proteins



Eukaryote cells

• Organelles aremembrane-bound cell

parts - Mini “organs”that have uniquestructures and functions

• Located in cytoplasm



• Cell membrane – delicate lipid

and protein skin aroundcytoplasm

– found in allcells

Cell Structures



• Nucleus – a membrane-bound

sac evolved to storethe cell schromosomes(DNA)

– has pores: holes





• mitochondrion

– makes thecell s energy

– the moreenergy the cellneeds, the moremitochondria ithas



• Ribosomes – build proteins from

amino acids in

cytoplasm – may be free-

floating, or – may be attached to

ER – made of RNA



• Endoplasmicreticulum – may be smooth :

builds lipids andcarbohydrates

– may be rough :stores proteinsmade by attachedribosomes



• Golgi Complex – takes in sacs of

raw materialfrom ER

– sends out sacscontaining

finished cell products



• Lysosomes – sacs filled with

digestive enzymes – digest worn out cell

parts

– digest foodabsorbed by cell



• Centrioles – pair of bundled tubes – organize cell

division



Cytoskeleton

• made ofmicrotubules

• found throughoutcytoplasm

• gives shape to cell& movesorganelles aroundinside.

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