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Microbiology for medical graduates
 

Microbiology for medical graduates

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Microbiology for medical graduates

Microbiology for medical graduates

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    Microbiology for medical graduates Microbiology for medical graduates Presentation Transcript

    • MICROBIOLOGY FOR MEDICAL GRADUATES WHAT YOU SHOULD KNOW Dr.T.V.Rao MDDR.T.V.RAO MD 11/16/2012 1
    • 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 11/16/2012 2
    • WHAT IS MEDICAL MICROBIOLOGY? The study of microorganisms “ (including bacteria, viruses, fungi and parasites) which are of medical importance and are capable of causing diseases in human beings”DR.T.V.RAO MD 11/16/2012 3
    • THE EARLY YEARS OF MICROBIOLOGY CONTRIBUTED BY DISCOVERY OF MICROSCOPEDR.T.V.RAO MD 11/16/2012 4
    • THE FIRST OBSERVATIONS• 1673-1723, Antoni van Leeuwenhoek described live microorganisms that he observed in teeth scrapings, rain water, and peppercorn infusions. DR.T.V.RAO MD 11/16/2012 5 Figure 1.2b
    • THE EARLY YEARS OF MICROBIOLOGY• How Can Microbes Be Classified? • Carolus Linnaeus (Swedish) developed taxonomic system for naming plants and animals and grouping similar organisms together • Leeuwenhoek’s microorganisms grouped into six categories as follows: • Fungi • Protozoa • Algae • Bacteria • Archaea • Small animals DR.T.V.RAO MD 11/16/2012 6
    • WHAT IS MEDICAL MICROBIOLOGY? THE PURPOSE OF LEARNINGWhat organisms cause infection?How they cause infection.How to treat them.How to prevent infection.DR.T.V.RAO MD 11/16/2012 7
    • 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 11/16/2012 8
    • THE HISTORICAL CONTRIBUTION IN THE SUBJECT OF MICROBIOLOGY BY … Darwin• Linnaeus • • Salk• Jenner • Watson & Crick • Jacob and Monod• Hooke • McClintock Woese• Leeuwenhoek • • Venter?• Lister• Pasteur• Koch DR.T.V.RAO MD 11/16/2012 9
    • DEFINITIONS• 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.• Proteomics is looking at the gene products DR.T.V.RAO MD 11/16/2012 10
    • LEARN THE CLASSIFICATION OF ORGANISMS• All living organisms are classified into: • Kingdom • Phylum (family) • Genus • Species• Organisms that can cause disease are many and varied and include: • Viruses • Bacteria • Fungi • Parasites DR.T.V.RAO MD 11/16/2012 11
    • RELEVANCE OF CLASSIFICATION• Different: • Diseases • Modes of transmission • Treatment-e.g. routinely use antibiotics don’t cure vira lfungalinfectionsDR.T.V.RAO MD 11/16/2012 12
    • THE GOLDEN AGE OF MICROBIOLOGY LOUIS PASTEUR CHANGES THE FUTURE OF MICROBIOLOGYDR.T.V.RAO MD 11/16/2012 13
    • FERMENTATION AND PASTEURIZATION• Pasteur demonstrated that these spoilage bacteria could be killed by heat that was not hot enough to evaporate the alcohol in wine.• Pasteurization is the application of a high heat for a short time. DR.T.V.RAO MD 11/16/2012 14 Figure 1.4 (1 of 3)
    • THE GOLDEN AGE OF MICROBIOLOGYDR.T.V.RAO MD 11/16/2012 15
    • THE GOLDEN AGE OF MICROBIOLOGY• Koch’s Postulates • Suspected causative agent must be found in every case of the disease and be absent from healthy hosts • Agent must be isolated and grown outside the host • When agent is introduced into a healthy, susceptible host, the host must get the disease • Same agent must be reisolated from now- diseased experimental hostDR.T.V.RAO MD 11/16/2012 16
    • NORMAL MICROBIOTA• Normal Microbiota prevent growth of pathogens.• Normal Microbiota 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.• Biofilms are extremely important in microbial ecology DR.T.V.RAO MD 11/16/2012 17
    • NORMAL MICRO BIOTA ON THE HUMAN BODYDR.T.V.RAO MD 11/16/2012 Table 18 14.1
    • NORMAL MICROBIOTA• Animals, including humans, are usually germfree in utero.• Microorganisms begin colonization in and on the surface of the body soon after birth.• Microorganisms that establish permanent colonies inside or on the body without producing disease make up the normal microbiota.• Transient microbiota are microbes that are present for various periods and then disappear. DR.T.V.RAO MD 11/16/2012 19
    • WE HAVE MORE MICROBES OCCUPYING OUR BODY THAN OUR OWN CELLS DR.T.V.RAO MD 11/16/2012 20
    • CLASSIFYING BACTERIAWhy bother?Different bacteria:• cause different diseases• are susceptible/resistant to different antibiotics• some bacteria are common normal flora whilst other closely related species are pathogensDR.T.V.RAO MD 11/16/2012 21
    • CLASSIFYING BACTERIAHow?• 1st into broad groups based on microscopic appearance• Then divided into species based on a range of different properties-often biochemical reactions e.g. some may be able to metabolise a sugar that others cannot.DR.T.V.RAO MD 11/16/2012 22
    • GRAM STAINMethod of differentiating bacteria.Can be either Gram +ve or Gram – ve depending on how they appear with the stain.Can then be further grouped based on shape (rod=long thin or coccus=round).Thus we end up with 4 combinations:G+ rod, G+ coccus, G- rod, G- coccusDR.T.V.RAO MD 11/16/2012 23
    • BACTERIAL CELL WALL MAKES THE BASIC DIFFERENCEDR.T.V.RAO MD 11/16/2012 24
    • GRAM STAIN G+ve G-ve• STAIN the slide with crystal violet for 1-2 min.• Flood slide with Grams iodine for 1-2 min.• Decolourise by washing the slide briefly with acetone (2-3 seconds).• Stain with safranin counterstain for 2 min.• View under microscope DR.T.V.RAO MD 11/16/2012 25
    • GRAM STAINGives an initial idea of the possible identity of the organism.Can be done without growing the organism (i.e. rapid result)Thus can be done on pus, joint fluid, sputum, CSF1st result available on blood culturesDR.T.V.RAO MD 11/16/2012 26
    • GRAM STAINRelevance of Gram reaction.• Gram +ve and gram –ve organisms ae susceptible to different groups of antibiotics.• Cause different diseases• Differ in their ability to survive in the environment- cleaning, infection control, outbreak management.DR.T.V.RAO MD 11/16/2012 27
    • GRAM POSITIVE COCCI • Clusters: usually characteristic of Staphylococcus spp., such as S. aureus • Chain or pairs: usually characteristic of Streptococcus spp., such as S. pneumoniaeDR.T.V.RAO MD 11/16/2012 28
    • GRAM POSITIVE BACILLI • Thick : usually characteristic of Clostridium spp., such as C. perfringens, C. difficle, C. tetani • Thin: e.g. Listeria spp.DR.T.V.RAO MD 11/16/2012 29
    • GRAM NEGATIVE BACILLI • Thin rods: usually characteristic of enterobacteriaceae (coliforms), such as E. Coli • Coccobacilli: usually characteristic of Haemophilus spp., such as H. influenzaeDR.T.V.RAO MD 11/16/2012 30
    • GRAM NEGATIVE BACILLI • Curved: usually characteristic of Vibrio spp.or Campylobacter spp., such as V. cholerae C. jejuni • Thin needle shape: usually characteristic of Fusobacterium spp.DR.T.V.RAO MD 11/16/2012 31
    • GRAM NEGATIVE COCCI • Diplococci: usually characteristic of Neisseria spp., such as N. meningitides or N. gonorrhea. Though In addition, Moraxella spp. and Acinetobacter spp.are often diplococcal in morphology. • Coccobacilli: usually characteristic of Acinetobacter spp., which can be either Gram-positive or Gram- negative, and is often called Gram- variable.DR.T.V.RAO MD 11/16/2012 32
    • WHAT CAN YOU SEE ON THE SLIDE?1. Gram +ve cocci2. Gram +ve bacilli3. Gram –ve cocci4. Gram –ve bacilli 53% 47% 0% 0% Staphylococcus aureus – 100x i lli lli i cc cc ci ci co co ba ba e e e e +v –v +v –v m m m m ra ra ra ra G G G G DR.T.V.RAO MD 11/16/2012 33
    • WHAT CAN YOU SEE ON THE SLIDE?1. Gram +ve cocci2. Gram +ve bacilli Streptococcus pneumoniae3. Gram –ve cocci4. Gram –ve bacilli 68% 16% 11% 5% i lli lli i cc cc ci ci co co ba ba e e e e +v –v +v –v m m m m ra ra ra ra G G G G DR.T.V.RAO MD 11/16/2012 34
    • WHAT CAN YOU SEE ON THE SLIDE?1. Gram +ve cocci2. Gram +ve bacilli3. Gram –ve cocci4. Gram –ve bacilli 36% 36% 14% 14% Pseudomonas aeruginosa i lli lli i cc cc ci ci co co ba ba e e e e +v –v +v –v m m m m ra ra ra ra G G G G DR.T.V.RAO MD 11/16/2012 35
    • VIRUSESSmall (50-300nm)Unable to replicateindependentlyInvade host cells and usetheir cellular machinery toreplicateInfluenza, Chickenpox(varicella), Herpes,Rhinovirus, HIV/AIDSOften difficult to treat DR.T.V.RAO MD 11/16/2012 36
    • 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 11/16/2012 37
    • PROTOZOA• Eukaryotes• Absorb or ingest organic chemicals• May be motile via pseudopods, cilia, or flagella DR.T.V.RAO MD 11/16/2012 38 Figure 1.1c
    • MULTICELLULAR ANIMAL PARASITES • Eukaryote • Multicellular animals • Parasitic flatworms and round worms are called Helminths. • Microscopic stages in life cycles.DR.T.V.RAO MD 11/16/2012 39 Figure 12.28a
    • THE ETIOLOGY OF INFECTIOUS DISEASES• Koch’s postulates are criteria for establishing that specific microbes cause specific diseases.• Koch’s postulates have the following requirements:(a) the same pathogen must be present in every case of the disease;(b) the pathogen must be isolated in pure culture;(c) the pathogen isolated from pure culture must cause the same disease in a healthy, susceptible laboratory animal;(d) the pathogen must be reisolated from the inoculated laboratory animal. DR.T.V.RAO MD 11/16/2012 40
    • KOCH’S POSTULATESDR.T.V.RAO MD 11/16/2012 41 Figure 14.7
    • EXCEPTIONS TO KOCH’S POSTULATES• Koch’s postulates are modified to establish etiologies of diseases caused by viruses and some bacteria, which cannot be grown on artificial media.• Some diseases, such as tetanus, have unequivocal signs and symptoms.• Some diseases, such as pneumonia and nephritis, may be caused by a variety of microbes.• Some pathogens, such as S. pyrogenes, cause several different diseases.• Certain pathogens, such as HIV, cause disease in humans only. DR.T.V.RAO MD 11/16/2012 42
    • Diseases and Infections • Disease-causing microorganisms are called pathogens. • Pathogenic microorganisms have special properties that allow them to invade the human body or produce toxins. • When a microorganism overcomes the body’s defenses, a state of disease results.DR.T.V.RAO MD 11/16/2012 43
    • PATHOLOGY, INFECTION, AND DISEASE• Pathology is the scientific study of disease.• Pathology is concerned with the • etiology (cause), • pathogenesis (development), • effects of disease – structural and functional changes brought about by disease.• Infection is the invasion and growth of pathogens in the body.• A host is an organism that shelters and supports the growth of pathogens.• Disease is an abnormal state in which part or all of the body is not properly adjusted or is incapable of performing normal functions.• Infection disease – presence of particular microorganism in part of the body where is not usually found. DR.T.V.RAO MD 11/16/2012 44
    • IMMUNITY PROTECTS FROM EVENTS WITH INFECTIONSDR.T.V.RAO MD 11/16/2012 45
    • CLASSIFYING INFECTIOUS DISEASES• Every disease alters body structures and functions• A patient may exhibit • symptoms (subjective changes in body functions) • Pain or body discomfort • signs (measurable changes), which a physician uses to make a diagnosis (identification of the disease) • Fever, swelling, paralysis• A specific group of symptoms or signs that always accompanies a specific disease is called a syndrome. DR.T.V.RAO MD 11/16/2012 46
    • MICROORGANISMSDR.T.V.RAO MD 11/16/2012 47 Figure 1.1
    • CLASSIFYING INFECTIOUS DISEASES• Communicable diseases are transmitted directly or indirectly from one host to another. • Chicken pox, genital herpes, • A contagious disease is one that is easily spread from one person to another.• Noncommunicable diseases are caused by microorganisms that normally grow outside the human body and are not transmitted from one host to another • Tetanus, Clostridium tetani DR.T.V.RAO MD 11/16/2012 48
    • THE MODERN AGE OF MICROBIOLOGYDR.T.V.RAO MD 11/16/2012 49
    • THE MODERN AGE OF MICROBIOLOGY• Microbial Genetics • Avery, MacLeod, and McCarty determined genes are contained in molecules of DNA • Beadle and Tatum established that a gene’s activity is related to protein function • Translation of genetic information into protein explained • Rates and mechanisms of genetic mutation investigated • Control of genetic expression by cells described DR.T.V.RAO MD 11/16/2012 50
    • THE MODERN AGE OF MICROBIOLOGY• Molecular Biology • Explanation of cell function at the molecular level • Genome sequencing • Pauling proposed that gene sequences could • Provide understanding of evolutionary relationships and processes • Establish taxonomic categories that reflect these relationships • Identify existence of microbes that have never been cultured • Woese determined that cells belong to bacteria, archaea, or eukaryotes • Cat-scratch fever caused by unculturable organism DR.T.V.RAO MD 11/16/2012 51
    • THE MODERN AGE OF MICROBIOLOGY • Recombinant DNA Technology • Genes in microbes, plants, and animals manipulated for practical applications • Production of human blood- clotting factor by E. coli to aid hemophiliacs • Gene Therapy • Inserting a missing gene or repairing a defective one in humans by inserting desired gene into host cellsDR.T.V.RAO MD 11/16/2012 52
    • DISCOVERY OF ANTIMICROBIAL AGENTS _________  Alexander Fleming (1881 – 1955), a Scottish biologist and pharmacologist, observed bacterial staphylococci colonies disappearing on plates contaminated with mold.  Fleming extracted the compound from the mold responsible for destruction of the bacterial colonies.  The product of the mold was named penicillin, after the Penicillium mold from which it was derived.  Nobel Prize in Physiology of Medicine in 1945. Images: Penicillium mold, PHIL #8396; Staphylococcus aureus on DR.T.V.RAO MD 11/16/2012 53 antibiotic test plate, PHIL #2641; Poster attached to a mailboxFrom the Virtual Microbiology Classroom on ScienceProfOnline.com offering advice to World War II servicemen, 1944, NIH
    • THE MODERN AGE OF MICROBIOLOGY• How Do We Defend Against Disease? • Serology • The study of blood serum • Von Behring and Kitasato – existence in the blood of chemicals and cells that fight infection • Immunology • The study of the body’s defense against specific pathogens • Chemotherapy • Fleming discovered penicillin • Domagk discovered sulfa drugs DR.T.V.RAO MD 11/16/2012 54
    • 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 11/16/2012 55
    • THE BIRTH OF MODERN CHEMOTHERAPY • 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 11/16/2012 56
    • 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. DR.T.V.RAO MD 11/16/2012 57 Figure 1.4 (3 of 3)
    • MODERN BIOTECHNOLOGY AND GENETIC ENGINEERING• Biotechnology, the use of microbes to produce foods and chemicals, is centuries old.• Genetic engineering is a new technique for biotechnology. Through genetic engineering, bacteria and fungi can produce a variety of proteins including vaccines and enzymes.DR.T.V.RAO MD 11/16/2012 58
    • 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 DR.T.V.RAO MD 11/16/2012 59
    • SELECTED NOVEL PRIZES IN PHYSIOLOGY OR MEDICINE1901* von Behring Diphtheria antitoxin1902 Ross Malaria transmission1905 Koch TB bacterium1908 Metchnikoff Phagocytes1945 Fleming, Chain, Florey Penicillin1952 Waksman Streptomycin1969 Delbrück, Hershey, Luria Viral replication1987 Tonegawa Antibody genetics1997Prusiner Prions2003Agre, Mackirron water and ion channels2005 Marshall, Warren Helicobacter and ulcers2008 Hausen Papilloma and viruses * The first Nobel Prize in Physiology or Medicine. DR.T.V.RAO MD 11/16/2012 60
    • UNIVERSAL PRECAUTIONS SET UP BY CDC• Use gloves, gowns, masks and goggles• Minimize risk of needle sticks• Disinfections procedure• Preventative treatment after exposure• Reduce risk• Treat all patients the same• HBV greater risk than HIV DR.T.V.RAO MD 11/16/2012 61
    • DEAR STUDENTS NEVER FORGET TO WASH HANDS AFTER HANDLING PATIENTS OR INFECTED MATERIALDR.T.V.RAO MD 11/16/2012 62
    • VISIT ME FOR MORE ARTICLES OF INTEREST ON MICROBIOLOGY, INFECTIOUS DISEASES…DR.T.V.RAO MD 11/16/2012 63
    • • Programme Created by Dr.T.V.Rao MD for Undergraduate Medical and Paramedical Students for orientation in Learning Medical Microbiology • email • doctortvrao@gmail.comDR.T.V.RAO MD 11/16/2012 64