INTRODUCTION 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 pathogenic Many are beneficial Dr.T.V.Rao MD
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Defining Microbiology 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. Dr.T.V.Rao MD
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What is Microbiology • Study of different Microorganisms • Can be Bacteria Viruses Parasites Fungus Dr.T.V.Rao MD
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What are Microorganisms • Microbes are products of evolution, Consequence of Natural selection operating upon vast array of genetically diverse organisms Dr.T.V.Rao MD
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History of Microbiology 1673-1723, Antoni van Leeuwenhoek (Dutch) described live microorganisms that he observed in teeth scrapings, rain water, and peppercorn infusions.
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Anton van Leeuwenhoek 1674 - 1st person to actually see living microorganisms
荷兰人吕文虎克 （Leeuwenhoek）1632-1723
“wee animalcules” Dr.T.V.Rao MD
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History of Microbiology The Germ Theory of Disease 1835: 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. Dr.T.V.Rao MD
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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. Dr.T.V.Rao MD
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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. Dr.T.V.Rao MD
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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. Dr.T.V.Rao MD
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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 Dr.T.V.Rao MD
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Other Objectives • To teach the basic immunological principles • Immunological methods for the study immunological disorders Dr.T.V.Rao MD
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Coverage of subject • General Microbiology • Bacteriology • Mycology • Virology • Immunology • Parasitology Dr.T.V.Rao MD
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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. Dr.T.V.Rao MD
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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 Dr.T.V.Rao MD
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Classification of Microorganisms • Three domains – Bacteria – Archaea – Eukarya • Protists • Fungi • Plants • Animals Dr.T.V.Rao MD
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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. Dr.T.V.Rao MD
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Edward Jenner Vaccinating a Child
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Louis Pasteur 1922 - 95 • Contributed best in Microbiology • Sterilization • Hot Air oven • Autoclave • Anthrax vaccine • Rabies vaccine • Built the Pasteur Institute Dr.T.V.Rao MD
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Louis Pasteur • Pasteur coined the word Vaccine • Vacca – Cow cow pox virus are given for the prevention of Small Pox • Louis Pasteur considered the father of Modern Microbiology Dr.T.V.Rao MD
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Robert Koch 1843 - 1910 • A German scientist • Formulated the Bacteriological techniques • Staining Methods • Discovered the Mycobacterium and Vibrio cholera
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Biological Principles illustrated by Microbiology
Microbiology
Biochemistry
Molecular Biology Dr.T.V.Rao MD
Genetics
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Microorganisms Non-cellular organism Virus
Prokaryotes Bacterium Eukaryotes Others
Fungi Prions Viroid Dr.T.V.Rao MD
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Organisms included in the study of Microbiology 1. Bacteria
2. Protozoans 3. Algae 4. Parasites 5. Yeasts and Molds Fungi
6. Viruses
Bacteriology Protozoology Phycology Parasitology
Mycology Virology Dr.T.V.Rao MD
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Man has Evolved So also the Microbes
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How to Study Medical Microbiology? Fundamentals of Microbiology Bacteriology Virology
•Biological Properties •Morphology, identification, •Antigenic structure •Pathogenesis and Pathology •Clinical findings •Diagnostic Laboratory Tests •Immunity •Treatment & Prevention •Epidemiology & Control
Mycology Dr.T.V.Rao MD
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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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Summary of differences between prokaryote and eukaryote cells Prokaryotic cells
Eukaryote cells
Small cell (< 5µm)
Larger cells (> 10 µm)
Always unicellular
Often multicellular
No nucleus or any membrane bound organelles
Always have nucleus and membranes bound organelles.
DNA circular, without proteins
DNA is linear and associated with proteins to form chromatin.
Ribosomes are small 70S
Ribosomes are large 80S
No cytoskeleton
Always have cytoskeleton
Motility by rigid rotating flagellum made from flagellin
Motility by flexible waving cilia or flagella made from tubulins.
Cell division is by binary fission
Cell division is by meiosis and mitosis.
Reproduction is always asexual
Reproduction is sexual and asexual.
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.
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.
Figure 1-9: Gram Stain
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.
Figure 3-3. Morphologic arrangements of bacteria.
Figure 1-10: 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.
Figure 1-11. 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.
Figure 1-13. Binary fission. Note that DNA replication must occur before the actual splitting (fission) of the parent cell.
Pathogenic Prokaryotes Bacteria Mycoplasma
Spirochetes Chlamydiae Rickettsia Actinomyces Dr.T.V.Rao MD
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Bacteria • Prokaryotes • Peptidoglycan cell walls • Binary fission • For energy, use organic chemicals, inorganic chemicals, or photosynthesis Dr.T.V.Rao MD
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Viruses A viral particle consists of a nucleic acid molecule, either DNA or RNA, enclosed in a protein coat, or capsid
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
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 Dr.T.V.Rao MD
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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 Dr.T.V.Rao MD
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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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Prion A 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), GerstmannSträussler-Scheinker disease, fatal familial insomnia , and Bovine spongiform encephalopathy (BSE) Dr.T.V.Rao MD
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Viroid Small, single-stranded, covalently closed circular RNA molecules existing as highly base-paired rod-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 The RNA molecule contains no protein-encoding genes, and the viroid kind is therefore totally dependent on host functions for its replication The RNAs of viroids have been shown to contain inverted repeated base sequences at their 3' and 5' ends, a characteristic of transposable elements and retroviruses. Thus, it is likely that they have evolved from transposable elements or retroviruses by the deletion of internal sequences
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Koch’s Postulates 1 The bacterium should be constantly associated with lesions of Disease 2 It should be possible to isolate the bacterium in pure culture from the lesions 3 Inoculation of such pure culture into laboratory animal should reproduce the lesions of the disease 4 It is possible to reisolate the bacterium in pure culture from the lesions produced in the experimental animal
Additional criterion specific antibodies in the serum of patients suffering with disease Dr.T.V.Rao MD
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Koch’s postulates
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Scientific era of Antibiotics 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. Dr.T.V.Rao MD
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Discovery of Antibiotics • Alexander Fleming (1881-1955)
Sir Alexander Fleming
Ernst Boris Chain
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Sir Howard Walter Florey
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Microbes are used to produce Antibiotics • Penicillin • Mold – Pencillium notatum
• 1928 Alexander Fleming
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Modern Developments • Bacteriology is the study of bacteria. • Mycology is the study of fungi. • Parasitology is the study of protozoa and parasitic worms. • Recent advances in genomics, the study of an organism’s genes, have provided new tools for classifying microorganisms.
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Microbes and Human Disease • Normal micro biota prevent growth of pathogens. • Normal micro biota produce growth factors such as folic acid and vitamin K.
• Resistance is the ability of the body to ward off disease. • Resistance factors include skin, stomach acid, and antimicrobial chemicals. Dr.T.V.Rao MD
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How to Study Medical Microbiology? Fundamentals of Microbiology Bacteriology Virology
•Biological Properties •Morphology, identification, •Antigenic structure •Pathogenesis and Pathology •Clinical findings •Diagnostic Laboratory Tests •Immunity •Treatment & Prevention •Epidemiology & Control
Mycology Dr.T.V.Rao MD
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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 Dr.T.V.Rao MD
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• Staphylococcus aureus • Staphylococcus epidermidis
• Streptococcus pneumonia • Vibrio cholera • Rhodospirillium rubrum
• Bacillus subtilis • Micrococcus luteus
• • • • • • • • • •
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Escherichia coli Bacillus anthrasis Salmonella enteridis Streptococcus pyogenes Steptococcus lactis Streptococcus faecalis Erlichia canis Campylobacter jujuni Helicobacter pylori Enterobacter aerogenes 56
Microbes Benefit Humans 1.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 Cough Botulism Typhoid Fever Measles Cholera Scarlet Fever Mumps Syphilis Gonorrhea Herpes 1 Chlamydia Tuberculosis Herpes 2 Meningitis Tetanus RMSV Strep Throat Lyme Disease AIDS Black Plague Diarrhea Dr.T.V.Rao MD Gangrene
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Progress of Hepatitis Viruses • 1947, concepts of hepatitis A and serumtransmitted 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) Dr.T.V.Rao MD
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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 Dr.T.V.Rao MD
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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, Dr.T.V.Rao MD
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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)
Taxonomic classification of parasitic organisms • Parasites are classified into 2 sub-kingdoms: protozoa (unicellular) and metazoa (multicellular) • Protozoan (unicellular) parasites are classified according to morphology and means of locomotion. There are 45,000 protozoa species. Most species that cause human disease belong to the phylum's sarcomastigophora and apicomplexa • Metazoa (multicellular) include the worms (helminths) and arthropoda (posses an external skeleton) e.g. ticks, lice • Note that the genus starts with a capital letter and the species is always written in italics, e.g. Plasmodium falciparum, Giardia
lamblia
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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 Dr.T.V.Rao MD
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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 Dr.T.V.Rao MD
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Pathogenesis Immunity
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Immunity Protects the Living by Complex Mechanisms
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Why we should Medical Microbiology • We study the Microbes which infects and causes Diseases • We study their Diagnosis Prevention Treatment Dr.T.V.Rao MD
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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 Dr.T.V.Rao MD
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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 Dr.T.V.Rao MD
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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. Dr.T.V.Rao MD
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Commonly Used Antibiotics • • • • • • •
Penicillin Cephalosporins, Tetracycline's Quinolones Vancomycin Chloramphenicol Drugs for Tuberculosis eg Streptomycin Dr.T.V.Rao MD
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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 Dr.T.V.Rao MD
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What Skills You should Develop Able to identify the Infective Conditions Timely Diagnosis Choosing appropriate tests Selection of Antibiotics Implement measures to prevent diseases in patients and Society Dr.T.V.Rao MD
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Protect Yourself from Infections • Certain infections can infect you • Eg HIV, Hepatitis B infections,Tubercul osis,Many respiratory infections Dr.T.V.Rao MD
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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. Dr.T.V.Rao MD
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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 1901*
von Behring
Diphtheria antitoxin
1902
Ross
Malaria transmission
1905
Koch
TB bacterium
1908
Metchnikoff
Phagocytes
1945
Fleming, Chain, Florey
Penicillin
1952
Waksman
Streptomycin
1969
Delbrück, Hershey, Luria
Viral replication
1987
Tonegawa
Antibody genetics
1997
Prusiner
Prions
* The first Nobel Prize in Physiology or Medicine. Dr.T.V.Rao MD
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Students requirement for the course • • • • • •
Timetable Literature – books, etc Practical manual Laboratory coat Attendance and active participation Seek advice timely Dr.T.V.Rao MD
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• The Programme created by Dr.T.V.Rao MD for Medical students in the Developing world • Email •
[email protected]
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