1. Introduction to
Medical Microbiology
Dr.T.V.Rao MD

2. Program file made for Educational
Resource of IFCAI and University of
Hyderabad
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
2

3. IFCAI is a non-profit organization has been set up with the following objectives:
• To promote and ensure capacity building in Infection control training and research.
IFCAI is collaborating with India’s institute of eminence “University of Hyderabad”
for offering PG Diploma in IPC
• To award recognition in Infection control programmes.
• To undertake all activities aimed at creating awareness to address the increasing
health challenges faced by India.
• To focus on creating higher standards of Hygiene and Infection Control, driving
public health oriented research and consultancy initiatives for shaping Hygiene and
Infection Control policies.
• To offer customized programmes to address India’s Hygiene and Infection Control
needs.
• To create meaningful career prospects and opportunities for Hygiene and Infection
Control professionals.
• To establish standards in Hygiene and Infection Control education by enabling the
formation of an independent accreditation system.
• To create a network of world class institutes and faculty for training and producing
high quality Hygiene and Infection Control professionals.
• IFCAI is run by volunteers like Dr Ranga Reddy Burri, Dr TV Rao, Dr
Mustafa , Dr Shamanna and many others with vast national and
international exposure to Public health and IPC.
About IFCAI its Role and Contributions for present future
Needs to Educate and Control Infectious diseases

4. Aim of the Programme
• The world is going for more and more towards the
Digital learning ( e-learning). The Subject of
Medical Microbiology is wide and deep and given
time period to learn many details becomes
difficult. However students can orient with Digital
modules for rapid learning and makes their online
searches easier for rapid references.
Dr.T.V.Rao MD
Professor of Microbiology
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
4

5. Aims for Learning Medical
Microbiology
• What is medical
microbiology?
• Why is it relevant?
• Some important
concepts.
• Basic classification
of organisms.
• Classifying
bacteria. Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
5

6. What is Microbiology?
Microbes, or microorganisms are minute living
things that are usually unable to be viewed with
the naked eye.
What are some examples of microbes?
Bacteria, fungi, protozoa, algae, viruses
are examples!
Some are pathogenic
“Germ” refers to a rapidly growing cell.
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
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7. What is Microbiology
• Microbiology – study of
microorganisms (simple forms of life
visible only with a microscope)
• Microorganisms may be
–Normal flora
–Pathogenic

8. Why is it Important?
• Infection is one of the most important
causes of mortality and morbidity in the
population.
• Approximately 30% of hospital patients are
on antibiotics at any one time
• 1 in 10 patients acquires an infection whilst
in hospital.
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
8

9. The Early Years of Microbiology contributed by
discovery of Microscope
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
9

10. History of Microbiology started with
1673-1723, Antoni
van Leeuwenhoek
(Dutch) described
live microorganisms
that he observed in
teeth scrapings, rain
water, and
peppercorn
infusions. Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
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11. Pioneers of Microbiology
• Antoni van Leeuwenhoek, DE (1673)
– First observed live microorganisms
(animalcules)
• Schleiden and Schwann, DE
– Formulated Cell Theory: cells are the
fundamental units of life and carry out all
the basic functions of living things
• Pasteur, FR and Tyndall, UK (1861)
– Finally disproved S.G.
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
11

12. Pioneers of Microbiology
• Louis Pasteur (1822-1895), Chemist
– Fermentation (1857)
– Pasteurization: heat liquid enough to kill
spoilage bacteria (1864)
– Vaccine development – rabies
– Proposed the germ theory of disease
– Proposed aseptic techniques (prevent
contamination by unwanted microbes)
– Director of Pasteur Institute, Paris (1894)
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
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13. Pioneers of Microbiology
• Joseph Lister, UK (1867)
– Used phenol (carbolic acid) to disinfect wounds
– First aseptic technique in surgery
• Robert Koch, DE (1876)
– Postulates – Germ theory (1876)
– Identified microbes that caused anthrax (1876),
tuberculosis (1882) and cholera (1883)
– Developed microbiological media & streak plates
for pure culture (1881)
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
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14. The Golden Age of Microbiology
1857-1914
Beginning with Pasteur’s work, discoveries
included the relationship between microbes
and disease, immunity, and antimicrobial
drugs
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
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15. 15
Microbiology
• The study of organisms too small to
be seen without magnification
– bacteria
– viruses
– fungi
– protozoa
– Helminths (Parasites)
– algae
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

16. Classification of Organisms
• All living organisms are classified into:
• Kingdom
• Phyllum (family)
• Genus
• Species
• Organisms that can cause disease are many
and varied and include:
• Viruses
• Bacteria
• Fungi
• Parasites
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
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17. 17
Branches of study within
Microbiology
• Immunology
• Public health microbiology &
epidemiology
• Food, dairy and aquatic microbiology
• Biotechnology
• Genetic engineering & recombinant DNA
technology
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

18. 18
Microbes are involved in
• nutrient production & energy flow
• decomposition
• production of foods, drugs &
vaccines
• bioremediation
• causing disease
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

19. 19
Impact of pathogens
• Nearly 2,000 different microbes
cause diseases
• 10 B infections/year worldwide
• 13 M deaths from infections/year
worldwide
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

20. 20
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

21. 21
Characteristics of microbes
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

22. 22
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

23. 23
Antonie van Leeuwenhoek
• First to observe
living microbes
• his single-lens
magnified up to
300X
(1632-1723) Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

24. Science of Microbiology begins
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
24

25. 25
Scientific Method
• Form a hypothesis - a tentative
explanation that can be supported or
refuted by observation &
experimentation
• A lengthy process of experimentation,
analysis & testing either supports or
refutes the hypothesis.
• Results must be published & repeated
by other investigators.
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

26. Hypothesis becomes Principles
• If hypothesis is supported by a growing body of
evidence & survives rigorous scrutiny, it moves
to the next level of confidence - it becomes a
theory
• Evidence of a theory is so compelling that the
next level of confidence is reached - it becomes
a Law or principle
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
26

27. Spontaneous generation
Early belief that some forms of life
could arise from vital forces present in
nonliving or decomposing matter.
(flies from manure, etc)

28. 28
Louis Pasteur Laid foundations
in Microbiology
• Showed microbes
caused fermentation &
spoilage
• Disproved spontaneous
generation of m.o.
• Developed aseptic
techniques.
• Developed a rabies
vaccine.
(1822-1895) Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

29. Germ theory of disease
Replaces Fate and Sins
Many diseases are caused by the growth
of microbes in the body and not by sins,
bad character, or poverty, etc.

30. Robert Koch
1843 - 1910
A German scientist
• Formulated the
Bacteriological
techniques
• Staining Methods
• Discovered the
Mycobacterium and
Vibrio cholera
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
30

31. 31
Robert Koch
• Established a sequence of
experimental steps to
show that a specific m.o.
causes a particular
disease.
• Developed pure culture
methods.
• Identified cause of
anthrax, TB, & cholera.
(1843-1910) Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

32. Robert Koch establishes many
Principals and postulations
• Koch perfected his methods of diagnostics and expanded on the
work of others.
– Koch invented the method of cultivating bacteria on nutrient
mediums, using potatoes as his source of nutrients for
bacteria, and created a medium that could be stored in dishes
created by his colleague Petri.
• Koch’s work on diseases and diagnostics culminated
with the creation of what are now known as Koch’s
Postulates.
– Koch’s Postulates are the 4 steps necessary to
confirm if a suspected pathogen is indeed the cause
of a disease.:
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
32

33. Robert Koch and Postulates
• Koch’s work on diseases and
diagnostics culminated with the
creation of what are now known as
Koch’s Postulates.
• Koch’s Postulates are the 4 steps
necessary to confirm if a suspected
pathogen is indeed the cause of a
disease.: 33
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

34. How do we know that a given pathogen
causes a specific disease?
• Koch's postulates
– the pathogen must be present in every case of the
disease
– the pathogen must be isolated from the diseased host &
grown in pure culture
– the specific disease must be reproduced when a pure
culture of the pathogen is inoculated into a healthy
susceptible host
– the pathogen must be recoverable from the
experimentally infected host
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
34

35. Koch's Postulates
1. Microorganisms are isolated from dead animals
2. Microorganisms are grown in pure culture
2b. Microorganisms are identified
3. Microorganisms are injected into healthy animals
4. Disease is reproduced in second animal
5. Microorganisms are grown in pure culture
5b. Identification of identical microorganism.
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
35

36. Figure 14.3, steps 1–2
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
36

37. Figure 14.3, steps 3–4
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
37

38. 5
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
38

39. Exceptions to Koch’s Postulates
• Microorganisms that are unable to
be cultured on artificial media
–(example: Treponema pallidum)
• 2 or more organism work in
synergy to cause a disease.
• Symptoms and diseases can be
causes by any one of several
microbes.
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
39

40. Joseph Lister
• Joseph Lister, was a
British surgeon and a
pioneer of antiseptic
surgery. By applying
Louis Pasteur's advances
in microbiology, he
promoted the idea of
sterile surgery while
working at the Glasgow
Royal Infirmary.
• .
40
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

41. Joseph Lister
• He instructed surgeons under his responsibility
to wear clean gloves and wash their hands before
and after operations with 5% carbolic acid
solutions. Instruments were also washed in the
same solution and assistants sprayed the solution
in the operating theatre. One of his additional
suggestions was to stop using porous natural
materials in manufacturing the handles of
medical instruments.
41
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

42. Joseph Lister
• Lister successfully
introduced carbolic
acid (now known as
phenol) to sterilise
surgical instruments
and to clean wounds,
which led to a
reduction in post-
operative infections
and made surgery
safer for patients. 42
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

43. 43
Taxonomy - system for organizing,
classifying & naming living things
• Domain - Archaea, Bacteria & Eukarya
• Kingdom - 5
• Phylum or Division
• Class
• Order
• Family
• Genus
• species
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

44. 44
Domains
• Eubacteria -true bacteria,
peptidoglycan
• Archaea –odd bacteria that live in
extreme environments, high salt,
heat, etc
• Eukarya- have a nucleus, &
organelles Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

45. 45
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

46. 46
Naming Microorganisms
• Binomial (scientific) nomenclature
• Gives each microbe 2 names
– Genus - noun, always capitalized
– species - adjective, lowercase
• Both italicized or underlined
– Staphylococcus aureus (S. aureus)
– Bacillus subtilis (B. subtilis)
– Escherichia coli (E. coli)
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

47. 47
Evolution- living things change
gradually over millions of years
• Changes favoring survival are retained & less
beneficial changes are lost.
• All new species originate from preexisting
species.
• Closely related organism have similar features
because they evolved from common ancestral
forms.
• Evolution usually progresses toward greater
complexity.
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India

48. Bacteria
• 500-800nm
• Capable of independent
replication
• Cause of most infections
seen in hospital
• Pneumonia, bacterial
meningitis, cellulitis,
UTI…
• Many different species
• Treated with antibiotics
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
48

49. Viruses
• Smallest known
infectious agents
• Subcellular
microorganism
– Have only nucleic acid
surrounded by a protein
coat
– Must live and grow in
living cells of other
organisms
Hepatitis virus
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
49

50. Viruses
Small (50-300nm)
Unable to replicate
independently
Invade host cells and use
their cellular machinery to
replicate
Influenza, Chickenpox
(varicella), Herpes,
Rhinovirus, HIV/AIDS
Often difficult to treat
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
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51. Viruses (cont.)
• Illnesses caused by viruses
– Colds
– Influenza
– Croup
– Hepatitis
– Warts
• Vaccines are available for many viruses
– AIDS
– Mumps
– Rubella
– Measles
– Herpes
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
51

52. Fungi
• Complex, large organisms
• Eukaryotes (as are humans!)
• Divided into yeasts &
moulds
• Cause a range of diseases
e.g.:
– Thrush
– Athletes foot
– Invasive & allergic
Aspergillosis
• Many diseases are
opportunistic.
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
52

53. Fungi
• Eukaryotic organisms
with rigid cell wall
• Yeasts
– Single-celled
– Reproduce by budding
• Molds
– Large, fuzzy,
multicelled organisms
– Produce spores
• Superficial infections
– Athlete’s foot
– Ringworm
– Thrush
• Can cause systemic
infections
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
53

54. Multicellular Parasites
• Organisms that live on or in another organism and
use it for nourishment
• Parasitic worms
– Usually due to poor
sanitation
– Roundworms
– Flatworms
– Tapeworms
• Parasitic insects
– Bite or burrow under the
skin
– Mosquitoes
– Ticks
– Lice
– mites
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
54

55. Protozoans
• Single-celled eukaryotic organisms, larger than
bacteria
• Found in soil and water
• Illnesses
– Malaria
– Amebic dysentery
– Trichomoniasis vaginitis
• Leading cause of death in developing countries
Protozoan
Trichomonas vaginalis
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
55

56. Normal Flora
• Human beings are not microbiologically
sterile.
• We are ALL covered with bacteria, fungi
and some parasites.
• Skin, nose, mouth, gastrointestinal tract …
• ~109 bacteria per gram of faeces
• Each person carries more non-human cells
on their body than their own
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
56

57. How Microorganisms Cause
Disease (cont.)
• Localized symptoms
– Swelling
– Pain
– Warmth
– Redness
• Generalized symptoms
– Fever
– Tiredness
– Aches
– Weakness
• Normal flora
– Provides a barrier
– Can cause an infection
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
57

58. How Microorganisms Cause
Disease
• Cause disease in variety of ways
– Use nutrients needed by cells and tissues
– Damage cells directly
– Produce toxins
• May remain localized or become systemic
• Transmission
– Direct contact
– Indirect contact
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
58

59. How Infections Are Diagnosed
• Steps to diagnosis and treatment
1. Examine the patient
• Presumptive diagnosis
• May or may not need additional tests
2. Obtain specimen(s)
• Label properly
• Include presumptive diagnosis
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
59

60. How Infections Are Diagnosed
(cont.)
3. Examine specimen directly
• Wet mount
• Smear
4. Culture specimen
Culture medium – contains nutrients
Examine culture visually and microscopically
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
60

61. How Infections Are
Diagnosed (cont.)
5. Determine
sensitivity to
antibiotics
6. Treat the patient as
ordered
• Antimicrobial – to
kill pathogen or
suppress its growth
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
61

62. Program file Created
by Dr.T.V.Rao MD for
the benefit of
Educational
resources for IFCAI
and University of
Hyderabad India
Dr.T.V.Rao MD @ IFCAI and
University of Hyderabad India
62