Welcome to Microbiology 130

What is Microbiology?The study of microorganisms, how they work, interact with the environment, and interact with us.

Microbiology has its roots in the study of bacteria, the largest and most important group of microorganisms.MicrobiologyFrom a cellular perspective, you might think the human body is mostly human. But youd be wrong. It is actually mostly bacterial. The typical adult body is composed of about 100 trillion (1014) cells. It harbors 1-2 x 1015 bacterial cells from at least 500 species about 20 times the number of human cells. MicrobiologyTotal number of microbial cells on Earth is about 5 X 1030.The total amount of carbon present in this population equals that of all plants on Earth.The total amount of nitrogen and phosphorous present in prokaryotes is over 10 times that of all plant biomass.Most prokaryotic cells reside underground in oceanic and terrestrial subsurfaces.Microorganisms: Friends or Foes?As we understand how microbes work, we can devise ways to increase their benefits and decrease their harmful effects.

What would be different about your life if all microorganisms ceased to exist?

The role of the infinitely small in nature is infinitely large. Louis PasteurFactors Responsible for Emerging InfectionsEmerging infections: New, reemerging or drug-resistant infections whose incidence in humans has increased within the past 2 decades or whose incidence threatens to increase in the near future.1992: MDR TB in NYC, 4,000 cases1993: Cryptosporidiosis in Milwaukee, 400,000 cases = 25% of citys population1993: Hantavirus in 4-corners area, 50% mort1995: Ebola in Kikwit, Zaire, 240 deaths1997+: E. coli O157:H7, National outbreaks1999: Nipah virus in Malaysia, encephalitis, 100 die2002: SARS in China2006: Chikungunya in India2007: Salmonella-contaminated peanut butter (48 states)2009: Severe Fever with Thrombocytopenia Syndrome (SFTS) China2014: Largest Ebola outbreak on record in West Africa, >20,000 deaths

Emerging and Reemerging Diseases

Infectious Diseases150 million people have died of AIDS, TB, and malaria alone since 1945 compared with 23 million lost to wars.

160 times more people have died from AIDS, malaria, respiratory and diarrheal diseases than in all natural disasters combined.

About 1/3 of deaths worldwide are due to infectious diseases.

United States9Figure: 01-07a

Caption:Death rates for the 10 leading causes of death in the United States: 1900. Infectious diseases were the leading causes of death in 1900, whereas today they are much less important. Microbial diseases are shown in red, nonmicrobial diseases in green. Data from the United States National Center for Health Statistics.

United States10Figure: 01-07b

Caption:Death rates for the 10 leading causes of death in the United States: 2000. Infectious diseases were the leading causes of death in 1900, whereas today they are much less important. Microbial diseases are shown in red, nonmicrobial diseases in green. Data from the United States National Center for Health Statistics.

Figure 1.3

Leading InfectiousKillers in the World(1998)From: Mokdad, A.H., J.S. Marks, D.F. Stroup, and J.L. Gerberding. Actual Causes of Death in the United States, 2000. JAMA, March 10, 2004. 291(10):1238-1245.

Antoni van Leeuwenhoek and his microscope(1632-1723)

Antoni van Leeuwenhoek (Dutch)Began making and looking through simple microscopes to answer What does it really look like?Often made a new microscope for each specimenExamined everything and visualized tiny animals, fungi, algae, and single celled protozoa; animalculesBy the end of 19th century, these organisms were called microbesLeeuwenhoek is known as Father of MicroscopyThe Early Years of Microbiology

And the motion of the most of these animalcules in the water was so swift, and so various, upwards, downwards, and round about, that twas wonderful to see.-Antoni van Leeuwenhoek, as reported to the Royal Society of London (1674)Leeuwenhoeks microorganisms grouped into five categories: FungiSmall animals (helminths)AlgaeProtozoaProkaryotes (bacteria)What is missing?Carolus Linnaeus (Swedish) - developed a system for naming plants and animals, and grouping similar organisms together (taxonomic system)

How Can Microbes Be Classified?The Microbial Umbrella

Eukaryotic (have membrane-bound nucleus)Obtain food from other organismsPossess cell walls composed of chitinComposed of:Molds multicellular; have hyphae; reproduce by sexual and asexual sporesYeasts unicellular; reproduce asexually by budding; some produce sexual sporesClassified by type of sexual sporeCommon Diseases:RingwormYeast infections (Candidiasis)CoccidioidomycosisHistoplasmosisCryptococcosisPneumocystis pneumoniaFungiFigure 1.4Examples of Fungi:Penicillium chrysogenum--a mold.

Examples of Fungi:Saccharomyces cerevisiae, a yeastParasitic Worms (Helminths)

Wuchereria in bloodTypes of Helminths:Cestodes = Tapeworms (Taenia)Trematodes = Flukes (Schistosoma)Nematodes = Roundworms (Ascaris)Unicellular or multicellularPhotosyntheticSimple reproductive structuresCategorized on the basis of pigmentation, storage products, and composition of cell wallNon-pathogenic except for their role in red tides and shellfish poisoningAlgaeFigure 1.6Examples of Algae:

Spirogyra sp.Figure 1.6Examples of Algae:

Diatoms

Single-celled eukaryotesSimilar to animals in their nutritional needs and cellular structureTypically live freely in water; some live inside animal hostsMost reproduce asexually; some reproduce sexually. Classified by mechanism of motility:Most are capable of locomotion by:Pseudopodia cell extensions that flow in direction of travelCilia numerous, short, hair-like protrusions that propel organisms through environmentFlagella extensions of a cell that are fewer, longer, and more whip-like than ciliaProtozoa

Examples of Protozoa:AmoebaEntamoeba histolytica causesamoebic dysenteryFigure 1.5Examples of Protozoa:

ParameciumBalantidium coli causesdiarrhea & dysenteryFigure 1.5Examples of Protozoa:

Trypanosoma brucei causesAfrican sleeping sicknessOther diseases caused by flagellates:-Chagas disease-Baghdad boil (Leishmania)-GiardiasisUnicellular and lack nucleiMuch smaller than eukaryotesFound everywhere there is sufficient moisture; some found in extreme environments (Archaea)Reproduce asexuallyTwo kindsBacteria cell walls contain peptidoglycan; a few lack cell walls; most do not cause disease and some are beneficialArchaea cell walls composed of polymers other than peptidoglycan; no diseasesProkaryotesFigure 1.7Examples of Prokaryotes:

Streptococcus sp.Viruses

T2 Bacteriophage

Human papillomavirusScientists searched for answers to four questions:Is spontaneous generation of microbial life possible?What causes fermentation?What causes disease?How can we prevent infection and disease?The Golden Age of Microbiology1857-1907Aristotle (384-322 B.C.) Greek philosopher and scientistStudied under PlatoTutored Alexander the GreatPromulgated spontaneous generation living things can arise from nonliving matter; water was key.This idea held for 2000 years1. Is Spontaneous Generation of Microbial Life Possible?Recipe for making miceJ.B. van Helmont 1620 ADIf a dirty undergarment is squeezed into the mouth of a vessel containing wheat, within a few days (say 21) a ferment drained from the garments and transformed by the smell of the grain, encrusts the wheat itself with its own skin and turns it into mice. And what is more remarkable, the mice from the grain and undergarments are neither weanlings or sucklings nor premature but they jump out fully formed.Francesco Redis Experiments(Italian physician 1626-1697)

Late 1600s: New view that animals come only from other animalsMid-1700s: Scientists did not believe large animals could arise spontaneously, but did believe microbes couldJohn Needham boiled beef gravy and plant infusions in vials, tightly sealed them with corksVials turns cloudy after a few daysObservation of microscopial animals of most dimensionsHis theory of a Life Force that causes inanimate matter to spontaneously come to life reinforced the idea of Spontaneous Generation.Needhams Experiments(British scientist 1713-1781)Lazzaro Spallanzani boiled infusions for almost an hour and sealed the vials by melting their slender necks closed.Vials remained clear, unless seals were broken and exposed to air1799: Concluded thatNeedham failed to heat vials sufficiently to kill all microbes or had not sealed vials tightly enoughMicroorganisms exist in air and can contaminate experimentsSpontaneous generation of microorganisms does not occurCritics said sealed vials did not allow enough air for organisms to survive and that prolonged heating destroyed the life forceSpallanzanis Experiments(Italian Catholic priest and scientist 1729-1799)Figure 1.12Louis PasteurFrench chemist (1822-1895)Father of Microbiology

Figure 1.12Pasteurs Experiments (1861)

Debate over spontaneous generation led to development of the scientific methodA group of observations leads scientist to ask question about some phenomenonThe scientist generates hypothesis (potential answer to the question)The scientist designs and conducts experiment to test hypothesisBased on observed results of experiment, scientist either rejects or modifies hypothesisThe Scientific MethodSpoiled wine threatened the livelihood of vintners, so they funded research into how to promote production of alcohol, but prevent spoilage by acid production during fermentationSome believed air caused fermentation reactions, while others insisted living organisms caused fermentationThis debate also linked to debate over spontaneous generation.2. What Causes Fermentation?2. What Causes Fermentation?

PasteurizationPasteurization in the 1800s:A process of heating grape juice just enough to kill most contaminating bacteria without changing the juices basic qualities so that it could then be inoculated with yeast to ensure that alcohol fermentation occurred. Pasteurization today is also used routinely on milk products and in industrial microbiology.Eduard Buchner(German scientist 1860-1917)Demonstrated that fermentation does not require living cellsThe presence of enzymes (cell-produced proteins) can promote the chemical reactions of fermentation.Beginning of biochemistry and microbial metabolismDevelopments Preceding the Germ Theory of Disease:Observations on Contagion:Prior to the 1800s, disease was attributed to evil spirits, astrological signs, imbalances in body fluids, foul vapors, and poisonous miasmasGirolamo Fracastoro (Italian philosopher 1478-1553)In 1546, conjectured that germs of contagion cause diseaseThree forms of contagion:Direct contact- Disease spread by touching infected personFomites- Disease spread by touching contaminated objectDistance- Disease spread by contaminated air and waterPasteur developed the germ theory of disease (1857).Robert Koch (German country doctor and scientist 1843-1910) studied causative agents of diseaseAnthrax; developed famous postulatesExamined colonies of microorganisms on solid media (agar & Petri plates)Because of his achievements, Koch is considered the Father of the Microbiological Laboratory3. What Causes Disease?Louis PasteurRobert Koch(1822-1895)(1843-1910)

Simple staining techniquesFirst photomicrograph of bacteriaFirst photomicrograph of bacteria in diseased tissueTechniques for estimating CFU/mlUse of steam to sterilize mediaUse of solid media and Petri dishesAseptic techniquesBacteria as distinct speciesLaboratory Microbiology Advances by Koch and OthersSuspected causative agent must be found in every case of the disease and be absent from healthy hostsAgent must be isolated and grown outside the hostWhen agent in introduced into a healthy, susceptible host, the host must get the diseaseSame agent must be re-isolated from diseased experimental hostKochs PostulatesTable 1.2Vibrio cholerae (bacterium)

Semmelweis and HandwashingListers Antiseptic TechniqueNightingale and NursingSnow infection control and epidemiologyJenners Vaccine field of immunologyEhrlichs Magic Bullets field of chemotherapy4. How Can We Prevent Infection and Disease?Ignaz Philipp Semmelweis(Hungarian physician 1818-1865)Observed high rate of puerperal fever in women who gave birth in Vienna hospitalHypothesized that cadaver particles from autopsies caused the infectionsAfter requiring medical students to wash hands with chlorinated lime water, mortality dropped significantlyRidiculed, forced to leave, returned to Hungary, and promoted hand-washingUnsuccessful in gaining support from European doctorsBecame depressed, and was committed to a mental hospitalDied from Streptococcus infection (the same microbe that causes puerperal fever)

Ignaz Philipp Semmelweis (1818-1865)Joseph Lister(English physician 1827-1912)

Aseptic Surgery:

An Operation in Edinburgh - 1870Lister began spraying wounds, surgical incisions, and dressings with carbolic acid (phenol)His work was accepted after he showed that it reduced deaths by two-thirdsSemmelweis vindicated

Florence Nightingale(English nurse 1820-1910)Introduced cleanliness and aseptic techniques into nursing practice during Crimean WarFounded the Nightingale School for Nurses

Mapped the cholera outbreak in London in 1854Identified the reservoir as the Broad Street PumpBeginning of epidemiology and infection controlDied of a stroke at age 45John Snow(English physician 1813-1858)

An 1866 cartoon describing cholera transmissionEdward Jenner(English physician 1749-1823)Discovered that vaccination using cowpox provided protection against potentially fatal smallpoxIntentionally inoculated a boy with pus collected from a milkmaids cowpox lesionLater infected same boy with smallpox pus Immunity developedBeginning of field immunology

Edward Jenner vaccinates James Phipps with pus from cowpox, 1798Louis Pasteur Watches the Vaccination of Joseph Meister for Rabies, 1885

Paul Ehrlich(German microbiologist 1854-1915)

Paul Ehrlich(German microbiologist 1854-1915)Discovered that chemicals could be used to kill microbes differentiallySought after a chemical (a magic bullet) that would destroy pathogens while remaining nontoxic to humansDiscovered Salvarsan to treat syphilis in 1909Beginning of chemotherapy

Alexander Fleming discovered Penicillin, 1928Figure 1.19 Some of the many scientific disciplines and applications that arose from the pioneering work of scientists just before and around the time of the Golden Age of Microbiology.

68All new questions:What are the Basic Chemical Reactions of Life? BiochemistryHow Do Genes Work?Microbial GeneticsMolecular BiologyRecombinant DNA TechnologyGene TherapyWhat Role Do Microorganisms Play in the Environment? Environmental MicrobiologyHow Do We Defend Against Disease? ImmunologyChemotherapy

The Modern Age of Microbiology

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