1. INTRODUCTION TO MICROBIOLOGY
Dr Nazia Khan
Assistant professor
College of medicine
Majmaah university

2. LEARNING OBJECTIVES
AFTER STUDYING THIS CHAPTER, YOU SHOULD BE ABLE TO:
Explain fundamentals of microbiology and its medical importance
Give brief history of evolution of microbiology with special contribution of Robert Koch and Louis Pasteur
Describe branches of microbiology
Describe basic characteristics of bacteria, viruses, parasites and fungi with examples of common diseases

3. INTRODUCTION The Science of Microbiology: Introduction
Microbiology is the study of microbes), a large and diverse group of microscopic organisms that exist as single cells or cell clusters; it also includes viruses, which are microscopic but not cellular.
Humans also have an intimate relationship with microorganisms; more than 90% of the cells in our bodies are microbes

4. The various categories of microbes include viruses, bacteria, archaea, protozoa, and certain types of algae and fungi.

5. WHY STUDY MICROBIOLOGY
our bodies has 10 times as many microbes as the total number of cells(indigenous microflora (or indigenous microbiota) and, for the most part, they are of benefit to us
Some colonize (inhabit) our bodies opportunistic pathogens (or opportunists).
essential for life on this planet. For example, some microbes produce oxygen by the process known as photosynthesis

6. involved in the decomposition of dead organisms and the waste products of living organisms(decomposers or saprophytes).
By definition, a saprophyte is an organism that lives on dead or decaying organic matter.
Saprophytes aid in fertilization by returning inorganic nutrients to the soil.
Algae and bacteria serve as food for tiny animals
Some microbes live in the intestinal tracts of animals, where they aid in the digestion of food

7. 7. Some bacteria and fungi produce antibiotics
8. Microbes are essential in the field of genetic engineering. such as insulin, various types of growth hormones, interferons, and materials for use as vaccine
9. For many years, microbes have been used as “cell models.”
10. They cause diseases
Infectious diseases are leading cause of death in the world and the third leading cause of death in the United States (after heart disease and cancer)

8. TERMINOLOGIES
Mutualism, one that benefits all of the contributing parties
Symbiosis: a continuing association of different organisms
Parasitism: If the exchange operates primarily to the benefit of one party, the association is described as parasitism, a relationship in which a host provides the primary benefit to the parasite
Disease-causing microorganisms are technically known as pathogens (also referred to as infectious agents)
The vast majority of known microbes are nonpathogens— microbes that do not cause disease.
GLOBAL BURDEN OF DISEASES- WHO 2013

9. GLOBAL BURDEN OF DISEASES- WHO 2013

10. PIONEERS IN THE SCIENCE OF MICROBIOLOGY .
Bacteria and protozoa were the first microbes to be observed by humans.
Among the most significant events in the early history of microbiology were
the development of microscopes,
bacterial staining procedures,
Techniques that enabled microorganisms to be cultured (grown) in the laboratory, and steps that could be taken to prove that specific microbes were responsible for causing specific infectious diseases.

11. Anton van Leeuwenhoek (1632–1723)
Anton van Leeuwenhoek was the first person to see live bacteria and protozoa,
“Father of Microbiology,” the “Father of Bacteriology,” and the “Father of Protozoology”.
He was a fabric merchant, a surveyor, a wine assayer, and a minor city official in Holland.
As a hobby, he ground tiny glass lenses, which he mounted in small metal frames, thus creating what today are known as single-lens microscopes or simple microscopes.
During his lifetime, he made more than 500 of these microscopes

12. Louis Pasteur (1822–1895) French chemist,
Below are some of his most significant contributions:
While attempting to discover why wine becomes contaminated with undesirable substances, Pasteur discovered what occurs during alcoholic fermentation
The theory of spontaneous generation.
He introduced the terms “aerobes” (organisms that require oxygen) and “anaerobes” (organisms that do not require oxygen).
He developed the process called Pasteurization to kill microbes

13. Contn……
He discovered the infectious agents that caused the silkworm diseases that were crippling the silk industry in France. He also discovered how to prevent such diseases.
Pasteur made significant contributions to the germ theory of disease—the theory that specific microbes cause specific infectious diseases.
Pasteur championed changes in hospital practices to minimize the spread of disease by pathogens.
Pasteur developed vaccines to prevent chicken cholera, anthrax, and swine erysipelas (a skin disease).
Pasteur developed a vaccine to prevent rabies in dogs and successfully used the vaccine to treat human rabies.

14. ROBERT KOCH(1843–1910) German physician He developed Koch’s Postulates
He discovered that B. anthracis produces spores, capable of resisting adverse conditions.
Koch developed methods of fixing, staining, and photographing bacteria.
Koch developed methods of cultivating bacteria on solid media. He obtained pure cultures of bacteria. He discovered the bacterium (M. tuberculosis) that causes tuberculosis and the bacterium (Vibrio cholerae) that causes cholera.
Koch’s work on tuberculin (a protein derived from M. tuberculosis) ultimately led to the development of a skin test valuable in diagnosing tuberculosis

15. KOCH’S POSTULATES
The microorganism or other pathogen must be present in all cases of the disease
The pathogen can be isolated from the diseased host and grown in pure culture
The pathogen from the pure culture must cause the disease when inoculated into a healthy, susceptible laboratory animal
The pathogen must be re-isolated from the new host and shown to be the same as the originally inoculated pathogen

17. Exceptions to Koch’s Postulates
Certain pathogens will not grow on artificial media OR fastidious (meaning fussy )Ex: viruses, rickettsias, chlamydias and the bacteria that cause leprosy and syphilis.
It is necessary to infect laboratory animals with the pathogen being studied( many pathogens are species-specific, meaning that they infect only one species of animal. For example, some pathogens that infect humans will only infect humans).
Some diseases, called synergistic infections, are caused not by one particular microbe, but by the combined effects of two or more different microbes. It is very difficult to reproduce such synergistic infections in the laboratory.
certain pathogens become altered when grown in vitro. Some become less pathogenic, whereas others become nonpathogenic. Thus, they will no longer infect animals after being cultured on artificial media.
not all diseases are caused by microbes

18. Branches of microbiology
Bacteriology: The study of bacteria
Mycology: The study of fungi
Protozoology: The study of protozoa
Parasitology: The study of parasites
Immunology: The study of the immune system
Virology: The study of viruses
Nematology: The study of the nematodes
Branches of microbiology

19. GEN CHARACTERISTICS-BACTERIA
Small (0.2 um in diameter and 2-8 um in length) - Need simple microscope
Prokaryotic
No specific nucleus
One chromosome only
DNA and RNA
No membrane bound organelle
70S ribosome
Replicate by binary fission
Cell membrane without sterol (except Mycoplasma)
Cell wall-Peptidoglycans
e.g. E.coli, Staph aureus

20. GEN CHARACTERISTICS-VIRUSES
Very Minute- Need electron microscope
Acellular
No nucleus
Either DNA or RNA
Replicates in host cells only
No ribosome
No functional cell membrane
No cell wall
e.g. Human immuno-deficiency virus, Varicella zoster virus

21. GEN CHARACTERISTICS-FUNGI
Small
Eukaryote
Proper nucleus, nuclear memb
More than 1 chromosome
Mitochondria & other cell bound organelle
80S ribosome
Cell membrane Ergosterol
Complex carbohydrate cell wall – Chitin, Mannan, Glucans
e.g. Candida albicans, Aspergillus

22. PROPERTIES OF MICROORGANISMS
Features
Viruses
Bacteria
Fungi
Parasites
Size µ
0.3-2µ
3-10µ
15-25µ#
Cell Type
Acellular
Prokaryote
Eukaryote
DNA/ RNA
Either
Both
Nucleic acid replication
Host cell
Continuous
G & S phase
Replication
Complex
Binary fission
Mitosis/ Meiosis
Organelle
Uses host
Not membrane bound
Membrane bound
Ribosomes
None
70S(30S+50S)
80S(40S+60S)
Cell memb
Env/Non env
No sterol #Mycoplasma
Ergosterol
Cholesterol
Cell wall
Peptidoglycan
Chitin, Glucan

26. Self assessment
Which of the following bacteria was not discovered by Robert Koch?
a)      Bacillus anthracis
b)      Mycobacterium tuberculosis
c)       Salmonella typhi
d)      Vibrio cholera
The primary use of Koch's postulates is to
Clearly identify and characterize a particular organism
Isolate organism from diseased individual
Demonstrate that the disease is caused by a microorganism
Develop vaccine for specific disease

27. Pasteurization is a process of sterilizing milk and it was discovered by
koch
Louis
Anton
Newton
Write the exceptions of koch’s postulates
Enlist the different branches of microbiology and their definition
Write the general characterstics of viruses
Write two infectious diseases caused by bacteria ,fungi, protozoa and viruses