Microbiology

1. Assist. Prof. Dr/ AbdulBasit Al-Ghoury
M.Sc. , M.D
3rd level / Medicine
Emirates International University
Faculty of Medicine and Health Sciences
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2. Medical Microbiology – Concerned with:
(i) Etiology (Agent-cause).
(ii) Pathogenesis (Mechanism of production of
disease).
(iii)Laboratory Diagnosis.
(iv) Treatment of infection.
(v) Epidemiology (spread, distribution, prevalence
of infection in the community).
(vi) Control and prevention in community.
Medical Microbiology

3. What is Microbiology?
 Micro - too small to be seen with the naked
eye.
 Bio – life.
 ology - study of.
INTRODUCTION

4.  Microbiology is generally the biology of
microorganisms. It is a bioscience for the study of the
evolution, Classification , morphology, physiology,
genetics, ecology of microbes under certain definite
conditions, The law of their life activities, and their
interaction with human being, animals or plants as
well as with natural environment.
INTRODUCTION

5.  Medical microbiology is one of the
essential basic sciences for Medicine. It
is the study of Biological characteristics
of microorganisms and their
relationships with human hosts.
INTRODUCTION

6. What is Microorganisms ?
 Microorganisms are creatures that are not
directly visible to the unaided eye, with
dramatically biologic diversity.
 Viruses , bacteria, fungi, protozoa and some
algae are all in this category.
INTRODUCTION

7. Distribution of microorganisms
 Air
 Soil
 Water
 Animals
 Human body
INTRODUCTION

8. Microbial World
 Age (3,5 billion
years).
 Abundance and
diversity: 60% of
biomass;
water, soil and air;
Over 4000 species
have been
described.
INTRODUCTION

9. Microbiology Studies
 Shape ( morphology);
 Structure, nutrition;
 Growth and multiplication;
 Follow relationships of mo with host and
environment.
INTRODUCTION

10. Branches of Microbiology:
 Bacteriology: study of bacteria
 Mycology: study of fungi
 Virology: study of viruses
 Parasitology: study of protozoa and
parasitic worms.
INTRODUCTION

11. Branches of Microbiology
 Immunology: study of immunity.
 Edward Jenner, UK: developed vaccination (1798)
 Metchnikoff, RU: discovered phagocytes (1884)
 Paul Ehrlich, DE: theory of immunity (1890)
 Chemotherapy:
 Treatment of disease by using chemical means.
 Antibiotics produced naturally.
 Synthetic drugs.
INTRODUCTION

12. Branches of Microbiology
 Chemotherapy
 Alexander Fleming, Scotland (1928) discovered
penicillin
 Selman Waksman, Ukraine (1944) discovered
streptomycin
- Problems:
 Toxicity of drugs => Selective toxicity.
 Resistance of bacteria to drugs.
INTRODUCTION

13. Microorganisms are
everywhere, but why is so
important to learn about
them?
Affect our lives in many
different ways.

15. IMPORTANCE OF MICROORGANISMS
 Microorganisms are the oldest forms of life.
 Production of foods.
 Decomposition (bioremediation).
 Without certain microorganism life could not exist;
produce O2 and N2 .
 Production of drugs & vaccines.
 Genetic engineering.
 Causing disease .
Microorganisms have killed more people than have ever
been killed in war.
INTRODUCTION

16. Microbes Benefit Humans:
 . Microbes produce various Food products
• Cheese, pickles, sauerkraut, green olives
• Yogurt, soy sauce, vinegar, bread
• Beer, Wine, Alcohol.
INTRODUCTION

17. . Microbes form the basis of the
food chain
 Marine and fresh water microorganisms
INTRODUCTION

18.  Bioremediation
INTRODUCTION
 Bacteria are primary decomposers -
recycle nutrients back into the
environment (sewage treatment
plants).

19.  Bioremediation
 Using microbes to clean up pollutants and
toxic wastes.
 Exxon Valdez - 1989
 2 Genera:
• Pseudomonas sp.
• Bacillus sp.
INTRODUCTION

20. . Microbes are used to produce Antibiotics
 Penicillin
 Mold:
• Penicillium notatum
 1928 Alexander Fleming
INTRODUCTION

21. . Bacteria synthesize chemicals that our
body needs, but cannot synthesize
 Example: E. coli
• B vitamins - for metabolism
• Vitamin K - blood clotting
 Escherichia coli
• Dr. Escherich
• Colon (intestine)
INTRODUCTION

22. -Gene Therapy Genetic Engineering
 Bacteria can be manipulated to produce
enzymes and proteins they normally would
not produce.
• Insulin
• Human Growth Hormone
• Interferon
INTRODUCTION

23. . Microbial Antagonism
 Our normal microbial flora ( Microbiota)
prevents potential pathogens from gaining
access to our body (N.S.I.R).
INTRODUCTION

24. Why Study Medical
Microbiology?
 The majority of serious diseases in humans (especially those of
early childhood) are due to microbial infections.
 Prior to the discovery of antibiotics and vaccines, a large
proportion of children died before adulthood because of
infectious disease.
 Till 1900, the average life expectancy in the United States was
40 years of age.
 In 2000 - 80 years, largely due to the near eradication of most
serious early childhood diseases.
 This trend is seen in the gap between developed and developing
countries in terms of causes of death (mortality).

25. 25

26. Microbes
 Pathogen or pathogenic - capable of producing
disease.
 Though only a minority of microorganisms are pathogenic,
practical knowledge of microbes is necessary for their treatment
so is highly relevant to medicine and related health sciences.
 Normal flora [normal microbiota] - not typically-
disease-causing.
 microorganisms normally found in and on healthy individuals.
• on the skin,
• in the eyes,
• in the nose,
• in the mouth,
• in the upper throat,
• in the lower urethra,
• in the lower intestine.

27. A, Influenza virus;
B, West Nile
Virus;
C, Staphylococcus aureus;
D, Streptococcus
pneumoniae.

28.  Microbial Morphology
 Microbial Cytology
 Microbial Physiology
 Microbial Ecology
 Microbial Genetics and molecular biology
 Microbial Taxonomy
 Microbial Pathogenesis.
Microbiologists may be interested in
various characteristics or activities of
microbs and may study:

29. Classification of
Organisms

30.  For many years, living organisms were
divided into two kingdoms:
 Animalia (animal) and
 Plantae (vegetable).
Classification

31. Classification Schemes
Plantae
Animalia
Plantae
Two kingdoms

32. Classification
 But after 1800s, scientists realized that these
two kingdoms could not adequately express the
diversity of life.
 Since the 1960s, the most widely used scheme
(5) five kingdoms.
 Viruses are separate group of biological entities,
although not organisms in the same sense as
Eukaryotes, Archaea and Bacteria.

33. Classification schemes
5 kingdoms
Plantae
Animalia
Plantae
Protista
Monera Fungi
Domain
Bacteria
(Eubacteria)
Domain
Archaea
(Archaeabacteria)
Prokaryotes
Eukaryotes

34. Classification
 3 major Domains of
Microorganisms:
 Bacteria
 Archaea
 Eukaryota (Eukarya)
 The first two are Prokaryotes
(Bacteria and Archaea)-
without true nucleus, while
the Eukaryotes all have a true
nucleus in each cell.
The 3 Domains. Source:
http://www.ucmp.berkeley.edu/alllife/images/domains_small.gif

35. Three Domain Classification
 Bacteria
 Archaea
 Eukaryota:
 Protista
 Fungi
 Plants
 Animals

36. Classification of Organisms

37. Classification of Organisms

38. Kingdom: Monera
 All organisms in the Kingdom of Monera are Prokaryotes.
 lack nuclei and organelles (nucleoid).
 most of their cell walls are made of peptidoglycan (the exceptions
are the archaebacteria).
 The archaebacteria have cell walls that lack peptidoglycan, cell
membranes that utilize different lipids, and ribosomes similar to
those found in Eukaryotes.
 The bacteria (eubacteria-true bacteria) are characterized by how
they metabolize resources, their means of motility, and their
shape.
 Most organisms in the Kingdom Monera reproduce through
binary fission (asexual) or conjugation (sexual).

39. Bacteria
 Most utilize flagella for movement.
 Digestion is extracellular (outside the cell) and
nutrients are absorbed into the cell.
 Circulation and digestion in Kingdom Monera is
accomplished through diffusion.
 Reproduction: sexual and asexual reproduction.
 O2 Dependent: aerobic and an aerobic.

40. Bacteria - what comes to mind?
 Diseases.
 Infections.
 Epidemics.
 Food Spoilage.
 Only 1% of all known bacteria cause human
diseases.
 About 4% of all known bacteria cause plant
diseases.
 95% of known bacteria are non-pathogens.

41. Taxonomy
 Taxonomy is the classification of organisms. The
most common system in use today is the Five
Kingdoms:
 Monera (Prokaryota),
 Protista,
 Fungi,
 Plantae, and
 Animalia.
 Organisms in each kingdom are divided into phyla.
 In each phylum, organisms are separated into classes.
 In each class, organisms are segregated into orders.
 In each order, organisms are divided into families.
 In each family, organisms are separated by genus.
 And finally, in each genus organisms are divided into species.

42. Prokaryotes
 Kingdom - Monera
 Domain - Bacteria
 Phylum – Proteobacteria
 Class – Gammaproteoba
 Order – Enterobacteriae
 Family – Enterobacteriace
 Genus – Escherichia
 Species – Escherichia coli

43.  Binomial (scientific) nomenclature
 Gives each microbe 2 names:
 Genus - noun, always capitalized and may be
abbreviated.
 species - adjective, lowercase, never abbreviated.
 A genus name may be used alone to indicate a genus
group; a species name is never used alone.
• eg: Bacillus subtilis
B. subtilis
 Both italicized or underlined
 Staphylococcus aureus ( S. aureus )
 Bacillus subtilis (B. subtilis)
 Escherichia coli (E. coli)
Nomenclature

44. Nomenclature
 Carolus Linnaeus established
the system of scientific
nomenclature in 1739.
 Each organism has two names  Binomial
nomenclature: Genus + specific epithet
(species)

45. Nomenclature
 Common or descriptive names
(trivial names).
 Names for organisms that may be in
common usage, but are not taxonomic
names.
• eg: tubercle bacillus
(Mycobacterium tuberculosis)
• meningococcus
(Neiserria meningitis)
• Group A streptococcus
(Streptococcus pyogenes)

46. Bacterial Classification
by
1) Morphology (shape).
2) Metabolism.
3) Staining, etc

47. 1- According the shapes:
 cocci (spherical),
 bacillus (rod shaped), and
 spirillum (spirals).
 polymorph

48. Classification of bacteria
• Cocci
 Micrococcus
 Staphylococci
• Irregular clusters of cocci
 Diplococci
• Pairs of cocci
 Streptococci
• Chains of cocci

49. Classification of bacteria
 Bacilli
 Rod like
 Diplobacilli
• Pairs of bacilli
 Streptobacilli
• Chains of bacilli
 Spirochetes
• Spiral

50. Size of bacteria
 Unit of microbial
measurement
 micrometers (um)
• 1 um being 10-6 m or
0.000001 m(1/25,000
inch)
 nanometers
• 1 nm being 10-9 or
0.000000001 m.
 Pathogenic bacterial
species vary from
approximately 0.4 to 2
um in size.

51. Louis Pasteur
"The role of the
infinitely small in
nature is infinitely
large"

52. Historical Perspectives

53. Historical
YEAR NAME ACHIEVEMENT
1st century BC Varo Concept of “Animalia
minuta”
1546 Fracostorius Contagion- Cause of
syphilis
1590 Jensen Hand lens
1683 Antony van
Leeuwenhoek
First Microscope
“Animalcules”
1678 Robert Hook Compound microscope
1745 Needham (Priest) Abiogenesis
1836 Schulze & Schwan Air contains microbes
1840 Oliver Homes, Poet
physician
Contageousness &
Puerperal fever
1846 Ignaz Semmelweis Cause, concept &
prophylaxis of child-bed
fever
1853 Augustino Bassi Silk worm disease due to
a fungus

54. Pioneers of Microbiology
 Robert Hooke, UK (1665)
 Proposed the Cell Theory.
 Observed cork with crude microscope
 All living things are composed of cells.
 Spontaneous generation:
 Some forms of life could arise spontaneously from
non-living matter.
 Francesco Redi, IT (1668)
 Redi’s experiments first to disapprove S.G.

55. Antonie van Leeuwenhoek
 First to observe living
microbes.
 his single-lens
magnified up to 300X.
(1632-1723)

56. Anton van Leeuwenhoek 1674
- 1st person to actually see living microorganisms
“wee animalcules”

57. Louis Pasteur
 French chemist
 Father/Founder of Modern
Microbiology.
 Fermentation – a
microbiological process
 Beer/Wine not produced
without microbes
 Showed microbes caused
fermentation & spoilage
 Disproved spontaneous
generation of m.o.
 Developed aseptic techniques.
 Developed a rabies vaccine.
(1822-1895)

58. Joseph Lister 1867
 Prof of Surgery,
Glasgow Royal
Informatory
 Introduced Antiseptic
Surgery.
 Called Father of
Antiseptic Surgery.

59. Robert Koch
 German general practitioner
 Perfected bacteriological
techniques
 Isolated pure cultures of
bacteria for the first time
 Discovered Anthrax bacilli,
Cholera vibrio, M. tuberculosis
 Father of Medical Microbiology
 Hypersensitivity.
 Established a sequence of
experimental steps to show
that a specific m.o. causes a
particular disease.
(1843-1910)

60. Highlights in the History of
Microbiology
1887
 Invented Petri Dish
(R.J. Petri)
1892
 Discovered viruses (Dmitri
Iosifovich Ivanovski)
1899
 Recognized viral
dependence on cells for
reproduction (Martinus
Beijerinck)
1900
 Proved mosquitoes carried
the yellow fever agent
(Walter Reed)
1910
 Discovered cure for syphilis
(Paul Ehrlich)
1928
 Discovered Penicillin
(Alexander Fleming)

61. Highlights in the History of
Microbiology
 1977
Developed a method to
sequence DNA (W.
Gilbert & F. Sanger)
 1983
Polymerase Chain
Reaction invented (Kary
Mullis)
 1995
First microbial genomic
sequence published (H.
influenzae) (TIGR)

62. Robert Koch - 1st to prove that
bacteria actually caused diseases
 Established “Scientific rules” to show a
cause and effect relationship between a
microbe and a disease.
• Koch’s Postulates

63. 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
the same disease when inoculated into a
healthy susceptible animal.
 4. The original organism must again be
isolated from the experimentally infected
animal.

64. Exceptions to Koch’s Postulates:
1. Some organisms have never been grown in
pure culture on artificial media.
Treponema pallidum - Syphilis

65. Mycobacterium leprae
Leprosy
Never been grown in pure culture on artificial media
Abdominal cavity of the Seven Banded Armadillo
Exceptions to Koch’s Postulates

66. Koch established the Microbial
Etiology of 3 important diseases
of his day:
 1. Cholera (fecal-oral disease)
• Vibrio cholerae
 2. Tuberculosis (pulmonary infection)
• Mycobacterium tuberculosis
 3. Anthrax (sheep and cattle)
• Bacillus anthracis

67. Golden Age of Microbiology 1857 - 1914
 Pasteur
• Pasteurization
• Fermentation
 Joseph Lister
• Phenol to treat surgical wounds – 1st attempt to control infections
caused by microoganisms.
 Robert Koch
• Koch’s Postulates
 Edward Jenner
• vaccination
 Paul Erlich
• 1st synthetic drug used to treat infections.
• Salvarsan - arsenic based chemical to treat Syphilis
• “salvation” from Syphilis

68. References
1) Geo. F. Brooks, et al (2012): Jawetz, Melnick, &
Adelberg’s Medical Microbiology, 24th edition, USA.
2) Farrar, J. et al. (2014): Manson’s Tropical Diseases,
23rd Edit. Elsevier Limited, USA.
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