Dr.T.V.Rao MD 1

A BEGINNING TO

MEDICAL MICROBIOLOGY

Dr.T.V.Rao MD

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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 pathogenicMany are beneficial as Commensal bacteria

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Microbiology defined as the study of organisms too small to be seen with the naked eye. These organisms include viruses, bacteria, algae, fungi, and protozoa. Microbiologists are concerned with characteristics and functions such as morphology, cytology, physiology, ecology, taxonomy, genetics, and molecular biology.

Defining Microbiology

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What is Microbiology

• Study of different Microorganisms

• Can be Bacteria Viruses Parasites Fungus

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Microbial World is Fascinating

•Viruses•Bacteria (Eubacteria) and Archaeabacteria

•Fungi (Yeasts and Molds)•Protozoa•Microscopic Algae

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What are Microorganisms

•Microbes are products of evolution, Consequence of Natural selection operating upon vast array of genetically diverse organisms

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History of Microbiology1673-1723, Antoni van Leeuwenhoek (Dutch) described live microorganisms that he observed in teeth scrapings, rain water, and peppercorn infusions.

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Scientific History of Microbiology

The Germ Theory of Disease1835: Agostino Bassi showed a silkworm

disease was caused by a fungus.1865: Pasteur believed that another silkworm

disease was caused by a protozoan.1840s: Ignaz Semmelweis advocated

handwashing to prevent transmission of puerperal fever from one OB patient to another.

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The Germ Theory of Disease• 1860s: Joseph Lister used a

chemical disinfectant to prevent surgical wound infections after looking at Pasteur’s work showing microbes are in the air, can spoil food, and cause animal diseases.

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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 dispprove S.G.

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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.

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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)

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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)

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History of microbiology Anton van Leeuwenhoek (1632–1723): was the first microbiologist and the first person to observe bacteria using a single-lens microscope of his own design. Louis Pasteur (1822–1895): Pasteur developed a process (today known as pasteurization) to kill microbes. pasteurization is accomplished by heating liquids to 63° to 65°C for 30 minutes or to 73° to 75°C for 15 seconds. Robert Koch (1843–1910): was a pioneer in medical microbiology and worked in cholera, anthrax and tuberculosis. He was awarded a Nobel prize in 1905 (Koch's postulates) he set out criteria to test. Alexander Fleming (1929): Discovered penicillin.

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Joseph Lister•1860s: Joseph Lister used a chemical disinfectant to prevent surgical wound infections after looking at Pasteur’s work showing microbes are in the air, can spoil food, and cause animal diseases.

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Learning Objectives •To teach the basic immunological principles

•Immunological methods for the study immunological disorders

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We all should be Familiar with

•General Microbiology

•Bacteriology•Mycology•Virology•Immunology•Parasitology

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Microbes in Our Lives•Microorganisms are organisms that are too small to be seen with the unaided eye.

•“Germ” refers to a rapidly growing cell.

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Microbes make the Universe

•There are > 5 x 1030 types Microbes in the world

•Humans have intimate relation with Microbes > 90% of the cells in our Body are Microbes

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Classification of Microorganisms

•Three domains•Bacteria•Archaea•Eukarya

• Protists• Fungi• Plants• Animals

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Naming and Classifying Microorganisms

• Carolus Linnaeus (1735) established the system of scientific nomenclature.

• Each organism has two names: the genus and specific epithet.

• Are italicized or underlined. The genus is capitalized and the specific epithet is lower case.

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Edward Jenner Vaccinating a

Child

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Louis Pasteur1922 - 1995

•Contributed best in Microbiology

•Sterilization•Hot Air oven•Autoclave•Anthrax vaccine•Rabies vaccine•Built the Pasteur Institute

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Louis Pasteur•Vacca – Cow cow pox virus are given for the prevention of Small Pox

•Louis Pasteur considered the father of Modern Microbiology

•Pasteur coined the word Vaccine

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Robert Koch1843 - 1910

•A German scientist•Formulated the Bacteriological techniques

•Staining Methods•Discovered the Mycobacterium and Vibrio cholera

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Koch's Postulates1. 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.

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Koch’s Postulates

Dr.T.V.Rao MD 28Figure 14.3, steps 1–2

Dr.T.V.Rao MD 29Figure 14.3, steps 3–4

Dr.T.V.Rao MD 30Figure 14.3, step 5

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Exceptions to Koch’s Postulates

• Microorganisms that are unable to be cultured on artificial media

• (example: Treponema pallidum)

• More organism work in synergy to cause a disease.

• Symptoms and diseases can be causes by any one of several microbes.

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Biological Principles illustrated by Microbiology

Microbiology

Biochemistry MolecularBiology Genetics

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Microorganisms

Non-cellular organism

Prokaryotes

Eukaryotes

Others Prions Viroid

Fungi

Bacterium

Virus

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Organisms included in the study of Microbiology

1. Bacteria2. Protozoans3. Algae4. Parasites5. Yeasts and Molds

Fungi6. Viruses

BacteriologyProtozoologyPhycologyParasitology

MycologyVirology

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How to Study Medical Microbiology?

Fundamentals of Microbiology

Bacteriology

Virology

Mycology

•Biological Properties• Morphology, identification, • Antigenic structure

•Pathogenesis and Pathology• Clinical findings

•Diagnostic Laboratory Tests•Immunity•Treatment & Prevention

• Epidemiology & Control

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Basic Classification of Microorganism

•Eukaryotes Large in size Mitochondria Present Membrane bound Nucleus Eg Algae Protozoa Fungi Slime Moulds Contains all enzymes for

production of metabolic energy

Prokaryotes Small in Size DNA not separated from

cytoplasm Mitochondria absent

Eg Bacteria

Contains all enzymes like Eukaryotes

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Prokaryotic Cell Structure

Prokaryotic cells are about 10 times smaller than eukaryotic cells. A typical Escherichia coli cell is about 1 μm wide and 2 to 3 μm long. Structurally, prokaryotes are very simple cells when compared with eukaryotic cells, and yet they are able to perform the necessary processes of life. Reproduction of prokaryotic cells is by binary fission, the simple division of one cell into two cells, after DNA replication and the formation of a separating membrane and cell wall.

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Bacteria•Prokaryotes•Peptidoglycan cell walls

•Binary fission•For energy, use organic chemicals, inorganic chemicals, or photosynthesis

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Bacterial Cell Wall The structure of bacterial cell walls is quite different from the relatively simple structure of eukaryotic cell walls, although they serve the same functions, providing rigidity, strength, and protection. The main constituent of most bacterial cell walls is a complex macromolecular polymer known as peptidoglycan (murein), consisting of many polysaccharide chains linked together by small peptide (protein) chains. Peptidoglycan is only found in bacteria. The thickness of the cell wall and its exact composition vary with the species of bacteria. The cell walls of “Gram-positive bacteria” have a thick layer of peptidoglycan combined with teichoic acid and lipoteichoic acid molecules. The cell walls of “Gram-negative bacteria” have a much thinner layer of peptidoglycan, but this layer is covered with a complex layer of lipid macromolecules, usually referred to as bacteria capsule.

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Figure 1-9: Gram Stain

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Figure 3-1. Various forms of bacteria, including single cocci, diplococci, tetrads, octads, streptococci, staphylococci, single bacilli, diplobacilli, streptobacilli, branching bacilli, loosely coiled spirochetes, and tightly coiled spirochetes.

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Capsule stain. The capsule stain is an example of a negative staining technique. The bacterial cells and the background stain, but the capsules do not. The capsules are seen as unstained “halos” around the bacterial

cells.

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. Flagellar arrangement. The four basic types of flagellar arrangement on bacteria: peritrichous, flagella all over the surface; lophotrichous, a tuft of flagella at one end;

amphitrichous, one or more flagella at each end; monotrichous, one flagellum.

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Binary fission. Note that DNA replication must occur before the actual splitting (fission) of the parent cell.

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Pathogenic Prokaryotes

Mycoplasma

Bacteria

Spirochetes

Rickettsia

Chlamydiae

Actinomyces

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Viruses

Viruses lack many of the attributes of cells, including the ability to replicate. Only when it infects a cell does a virus acquire the key attribute of a living system: reproduction

A viral particle consists of a nucleic acid molecule, either DNA or RNA, enclosed in a protein coat, or capsid

Viruses are known to infect all cells, including microbial cells. Host-virus interactions tend to be highly specific

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Discovery of Virus•Iwanovski

•a Russian chemist, 1892

•Tobacco Mosaic Disease

•Beijerinck confirmed•Walter Reed, USA

•Yellow fever virus•Ist human virus

Tobacco mosaic disease, caused by the tobacco mosaic virus

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Viruses• A virus is not a cell!• Viruses are replicated

only when they are in a living host cell

• Consist of DNA or RNA core

• Core is surrounded by a protein coat

• Coat may be enclosed in a lipid envelope

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What are Viruses• Viruses Dependent on Host

cells for necessary functions and Multiplication

•Intracellular parasites

•Contain either DNA or RNA never both.

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PrionA kind of infectious protein that can resist the digestion of proteinase

The cellular form of the prion protein (PrPc) is encoded by the host’s chromosomal DNA

An abnormal isoform of this protein (PrPres) is the only known component of the prion and is associated with transmissibility.

Kuru, Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker disease, fatal familial insomnia, and Bovine spongiform encephalopathy (BSE)

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ViroidSmall, single-stranded, covalently closed circular RNA molecules existing as highly base-pairedrod-like structures; they do not possess capsids

They range in size from 246 to 375 nucleotides in length. The extracellular form of the viroid is naked RNA—there is no capsid of any kindThe RNA molecule contains no protein-encoding genes, and the viroid is therefore totally dependent on host functions for its replicationThe RNAs of viroids have been shown to containinverted repeated base sequences at their 3' and 5' ends, a characteristic of transposable elements and retroviruses. Thus, it is likely that they have evolvedfrom transposable elements or retroviruses by the deletion of internal sequences

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1928: Alexander Fleming discovered the first antibiotic.

He observed that Penicillium fungus made an antibiotic, penicillin, that killed S. aureus.

1940s: Penicillin was tested clinically and mass produced.

Scientific era of Antibiotics

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Discovery of Antibiotics• Alexander Fleming (1881-1955)

Sir Alexander Fleming Ernst Boris Chain Sir Howard Walter Florey

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Microbes are used to produce Antibiotics

Penicillin Penicillin

• Mold • Pencillium notatum

• 1928 Alexander Fleming

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How to Study Medical Microbiology?

Fundamentals of Microbiology

Bacteriology

Virology

Mycology

•Biological Properties• Morphology, identification, • Antigenic structure

•Pathogenesis and Pathology• Clinical findings

•Diagnostic Laboratory Tests•Immunity•Treatment & Prevention

• Epidemiology & Control

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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

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•Staphylococcus aureus•Staphylococcus epidermidis

•Streptococcus pneumonia

•Vibrio cholera•Rhodospirillium rubrum•Bacillus subtilis•Micrococcus luteus

•Escherichia coli•Bacillus anthrasis•Salmonella enteridis•Streptococcus pyogenes•Steptococcus lactis•Streptococcus faecalis•Erlichia canis•Campylobacter jujuni•Helicobacter pylori•Enterobacter aerogenes

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Microbes Benefit Humans1.Bacteria are primary decomposers - recycle nutrients back into the environment (sewage treatment plants)

2. Microbes produce various food products •cheese, pickles, sauerkraut, green olives•yogurt, soy sauce, vinegar, bread•Beer, Wine, Alcohol

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Microbes are also capable of causing many diseases

Pneumonia Whooping CoughBotulism Typhoid Fever MeaslesCholera Scarlet Fever MumpsSyphilis Gonorrhea Herpes 1Chlamydia Tuberculosis Herpes 2Meningitis Tetanus RMSVStrep Throat Lyme Disease AIDSBlack Plague Diarrhea Gangrene

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Progress of Hepatitis Viruses

• 1947, concepts of hepatitis A and serum-transmitted hepatitis

• 1970, Dane particle was observed (hepatitis B virus)

• 1973, hepatitis A virus• 1978, non-A, non-B hepatitis viruses

(NANBV)• 1989, hepatitis C virus (HCV), hepatitis E

virus (HEV)• 1990-1994, non A-E hepatitis viruses• 1995, hepatitis G virus (HGV)• 1997, TT virus (TTV)

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Human Immunodeficiency Virus & AIDS

•1981, the first cases report about AIDS

•1983, HIV was isolated•1990s, HAART (cocktail therapy) was employed

•So far, no effective vaccine available

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HIV – AIDS •Luc Montaigner and Robert Gallo announce their discovery of the immunodeficiency virus (HIV) believed to cause AIDS. (American Society for Microbiology Archives)

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Parasitology• Parasitology is the study of

parasites .and their interactions with their hosts. The science of parasitology has a long history and has its roots in zoology, with its emphasis on the identification and classification of parasites and of life cycles,

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Taxonomic classification of parasitic organisms

•The classification of parasites is controversial - there is no universally accepted system

•Parasites form part of the animal kingdom which comprises some 800,000 identified species categorised into 33 phyla (but it is estimated that there may be ~10m species in total)

•The parasitic organisms that are of importance for human health are eukaryotes - they have a well defined chromosome in a nuclear membrane (as opposed to prokaryotes which have no nuclear membrane, e.g. bacteria)

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What Are Fungi• Considerable variation in

size.• Internal Molecular system• Well defined cell wall

composed of polysaccharides

• Gaining importance in Immunosupressed patients and increased use of Antibiotics

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Zoonotic Diseases

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How Humans Respond to Infections

Study of Immunology•In spite of Infection we survive with our ability to protect with a system inherent in our Body

•Called the Immune response comprises the Medical Immunology

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Modern Developments in Microbiology

•Immunology is the study of immunity. Vaccines and interferons are being investigated to prevent and cure viral diseases.

•The use of immunology to identify some bacteria according to serotypes (variants within a species) was proposed by Rebecca Lancefield in 1933.

Figure 1.4 (3 of 3)

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PathogenesisImmunity

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Why we should learn Medical Microbiology

•We study the Microbes which infects and causes Diseases

•We study their Diagnosis Prevention Treatment

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Modern Developments in Microbiology

• Immunology is the study of immunity. Vaccines and interferons are being investigated to prevent and cure viral diseases.

• The use of immunology to identify some bacteria according to serotypes (variants within a species) was proposed by Rebecca Lancefield in 1933.

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Must learn•Natural History of the Disease•Etiology•Pathogenesis•Laboratory Diagnosis•Treatment and Control and Prevention

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We must be familiar with Knowledge On

….• Names of the Microbes• Names of the diseases• Mode of transmission• Pathogenic Microbes• Commensal Organisms• Identify wether Bacteria,

Virus, Parasite or Fungi• Treating and Preventing

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The Birth of Modern Chemotherapy

• Treatment with chemicals is chemotherapy.• Chemotherapeutic agents used to treat infectious

disease can be synthetic drugs or antibiotics.• Antibiotics are chemicals produced by bacteria and fungi

that inhibit or kill other microbes.• Quinine from tree bark was long used to treat malaria.• 1910: Paul Ehrlich developed a synthetic arsenic drug,

salvarsan, to treat syphilis.• 1930s: Sulfonamides were synthesized.

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Commonly Used Antibiotics

•Penicillin•Cephalosporins,•Tetracycline's •Quinolones•Vancomycin•Chloramphenicol•Drugs for Tuberculosis eg Streptomycin

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Vaccines Produce Immunity

and Prevents Several Infections

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Commonly used Vaccines

•Small pox eradicated•BCG,•MMR•Polio oral Vaccine•Triple Antigen•Hepatitis B Vaccine

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Course objectives•To provide the student with the basic knowledge of micro-organisms in general

•To study the main characteristics of Microbes of medical importance

•To teach aseptic techniques•To provide an understanding of antimicrobial agents

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What Skills You should Develop

Able to identify the Infective ConditionsTimely DiagnosisChoosing appropriate testsSelection of AntibioticsImplement measures to prevent diseases in patients and Society

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Protect Yourself from Infections

•Certain infections can infect you

•Eg HIV, Hepatitis B infections,Tuberculosis,Many respiratory infections

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Working In the Hospital•Hospitals are not safe •Follow Universal precaution protect yourself as our patients can be source of Infection if you don't handle the matters with scientific knowledge.

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Medical Microbiology advanced Beyond our Imagination

Can we handle it ???

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Major Selected Nobel Prizes in Physiology or Medicine

* The first Nobel Prize in Physiology or Medicine.

1901* von Behring Diphtheria antitoxin1902 Ross Malaria transmission1905 Koch TB bacterium1908 Metchnikoff Phagocytes1945 Fleming, Chain, Florey Penicillin1952 Waksman Streptomycin1969 Delbrück, Hershey, LuriaViral replication1987 Tonegawa Antibody genetics1997 Prusiner Prions

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Students requirement for the course

•Timetable •Literature – books, etc •Practical manual•Laboratory coat•Attendance and active participation•Seek advice timely

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•The Programme Created by Dr.T.V.Rao MD for medical and paramedical Students in the

Developing World •Email

•doctortvrao@gmail.com