CHAPTER 1
HISTORY AND SCOPE OF
MICROBIOLOGY
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Part I
General Microbiology

Dr Sonal Saxena, MD
Director Professor and Head of the Department of Microbiology
Maulana Azad Medical College,
New Delhi
and
Dr Amala A Andrews, MD
Maulana Azad Medical College,
New Delhi
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INTRODUCTION
Microbiology study of the following:
Study of microorganisms (bacteria, fungi, parasites, viruses and prions)
Response of human host to microbes and their antigens
Normal flora—protects against pathogens and required for healthy life
Microbiome—impact on human health and diseases
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HISTORICAL PERSPECTIVE
AND NOTABLE MILESTONES
IN MICROBIOLOGY
Antonie van Leeuwenhoek first observed microorganisms
using ground lenses
Ignaz Semmelweis discovered that puerperal sepsis is
contagious and introduced the concept of antisepsis; he
demonstrated the importance of hand washing
Edward Jenner invented the smallpox vaccine
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Antonie van Leeuwenhoek

LOUIS PASTEUR
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Laid the foundation for sterilisation methods, the
steam steriliser, hot-air oven and autoclave
Understood growth needs of different bacteria
Obtained knowledge of anthrax
Attenuated chicken cholera bacilli
Developed vaccines for hydrophobia (rabies) and
anthrax
Coined the term ‘vaccine’
Proposed the germ theory of diseases

ROBERT KOCH
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Discovered tubercle bacilli and Vibrio cholerae
Developed bacteriological techniques
Conducted studies on anthrax bacillus
Developed staining techniques
Developed methods of obtaining pure culture of bacteria
using solid media
Koch’s postulates: Criteria for proving that a microorganism
isolated from a diseased person or animal is causally related
to the disease

NOTABLE
MILESTONES IN
MICROBIOLOGY
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Joseph Lister used carbolic acid for antiseptic surgery
Roux and Yersin discovered Diphtheria toxin
Paul Ehrlich studied toxin and antitoxin quantitation
Ernst Ruska invented the electron microscope to visualise viruses
Karl Landsteiner’s work on protein chemistry laid the foundation
for immunochemistry
Niels Jerne — Natural selection theory of antibody synthesis
Frank Burnett — Clonal selection theory

KOCH’S
POSTULATES
1) The microorganism should be constantly associated
with the lesions
2) Should be possible to isolate the organism in pure
culture
3) Inoculation of pure culture should produce similar
lesions in animal models
4) It should be possible to re-isolate the bacteria in pure
culture from lesions produced in experimental animals
Additional criterion: It should be possible to demonstrate
specific antibodies to the microbe
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MOLECULAR
MICROBIOLOGY
Major discoveries
W Gilbert and F Sanger — Sequencing of DNA (1977)
Kary Mullis — Polymerase chain reaction (1983)
H. influenzae — 1st microbial whole genome sequence
(1995)
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Table 1.1 Some notable Nobel
laureates and their contributions to
the science of microbiology
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Year Nobel laureate Work
1902 Ronal Ross Malaria
1905 Robert Koch Tuberculosis
1908 P Ehrlich and E Metchnikoff Immunity
1928 Charles Nicolle Typhus
1930 Karl Landsteiner Discovery of human blood
groups
1945 A Fleming, E Boris Chain and Howard
Walter Florey
Penicillin
1951 Max Theiler Yellow fever
1952 Selman A Waksman Streptomycin
1954 Franklin Enders, T H Weller and
F C Robbins
Poliomyelitis growth in
tissue
1960 F M Burnet and P B Medawar Acquired immunological
tolerance

Table 1.1 contd
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Year Nobel laureate Work
1966 Peyton Rous Tumor-inducing viruses
1969 M Delbruck, A D Hershey and S E
Luria
Replication mechanism and the genetic
structure of viruses
1975 D Baltimore, R Dulbecco and H
Martin Temin
Interaction between tumor viruses and
the genetic material of the cell
1976 Baruch S Blumberg and D Carleton
Gajdusek
New mechanisms of infectious disease
dissemination and Australian antigen
1980 Baruj Benacerraf, Jean Dausset and
George D Snell
Immunological regulation by cell
surface
1984 Niels K Jerne, Georges J F Kohler and
Cesar Milstein
Control of immune system and
monoclonal antibodies
1987 Susumu Tonegawa Generation of antibody diversity
1989 J Micheal Bishop and Harold E
Varmus
Origin of retroviral oncogenes
1996 Peter C Doherty and Rolf M
Zinkernagel
Specificity in cell-mediated immune
defense

Table 1.1 contd
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Year Nobel laureate Work
1997 Stanley B Prusiner Prions
2005 Barry J Marshall and J Robin Warren Discovery of Helicobacter pylori and its
role in gastritis and peptic ulcer disease
2008 Harald Hausen and Francoise Barre-S
and L Montagnier
Human papilloma viruses and human
immunodeficiency virus
2011 Bruce A Beutler, Jules A Hoffmann
and Ralph M Steinman
Activation of innate immunity and the
dendritic cell and its role in adaptive
immunity
2015 William C Campbell and Satoshi
Omura
Discovery of a novel therapy against
roundworm infection
2015 Youyou Tu Discovery of a novel therapy against
malaria
2018 James P Allison and Tasuko Honjo Though not directly related to
microbiology, their work explained the
process of negative inhibition of
immunity in cancer therapy

ANTIBIOTIC
ERA
Alexander Fleming discovered penicillin (1928)
Development of various antibiotics and vaccines followed
Smallpox was eradicated (1980)
Antibiotic resistance developed soon and has emerged as a
global emergency
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EPIDEMICS
AND
PANDEMICS
Challenge in control of infectious diseases
• 1300s: Black death (plague) in Europe and Asia
• 1918: Spanish flu (H1N1 virus)
• 1981: Discovery of AIDS (USA)
• New and emerging infectious diseases appeared from
time to time
Recent ones
• Zika virus: South America
• MERS-CoV: Middle East
• Nipah virus: Kerala, India
• SARS-CoV-2: Wuhan, China
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SCOPE OF
MICROBIOLOGY
Medical microbiology and its expanded role
Pharmaceutical industry
Food and dairy industry
Agricultural industry
Veterinary medicine and animal husbandry
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MEDICAL MICROBIOLOGY
Diagnosis, prevention and control of infectious diseases
Immunological studies and treatment of certain malignancies
Infection control and prevention in healthcare facilities
Recombinant DNA technology
Genetic manipulation
Molecular engineering
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OTHER FIELDS
Pharmaceutical industry: Development of drugs and vaccines
Food and dairy industry: Yeasts for fermentation of certain foods and beverages
Agricultural industry: Microbes are important for the fertility of soil and controlling plant
infections
Veterinary medicine and animal husbandry: Animal health and control of zoonotic infections
transmitted from animals to humans
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MICROORGANISMS
ASSOCIATED WITH
HUMAN INFECTIONS
Bacteria
Viruses
Fungi
Protozoa
Helminthes
Prions
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 Not all microorganism-host interactions result in disease
 Interplay of several factors determine whether disease develops or a
balanced coexistence results