كلية العلوم الطبيه التطبيقيه قسم تقنية المختبرات الطبيه

GENERAL MEDICAL MICROBIOLOGY MDL 234

Dr. Heavin Hannan

Microbial World and You

What is Microbiology? w Micro - too small to be seen with the naked eye w Bio - life w ology - study of or ( Science )

A Brief History of Microbiology The First Observations w 1. Robert Hooke observed that cork was composed of “little boxes”; he introduced the term cell (1665). w 2. Hooke’s observations laid the groundwork for development of the cell theory, the concept that all living things are composed of cells.

w 3. Anton van Leeuwenhoek, using a simple microscope, was the first to observe microorganisms (1673). w 4. Louis Pasteur demonstrated that microorganisms are in the air everywhere and offered proof of biogenesis (1861). w 5. Pasteur’s discoveries led to the development of aseptic techniques used in laboratory and medical procedures to prevent contamination by microorganisms.

Microbes in Our Lives w 1. Living things too small to be seen with the unaided eye are called microorganisms. w 2. Microorganisms are important in the maintenance of an ecological balance on Earth. w 3. Some microorganisms live in humans and other animals and are needed to maintain good health. w 4. Some microorganisms are used to produce foods and chemicals. w 5. Some microorganisms cause disease.

Organisms included in the study of Microbiology w 1. Bacteria w 2. Protozoans w 3. Algae w 4. Parasites w 5. Yeasts and Molds Fungi w 6. Viruses w Bacteriology w Protozoology w Phycology w Parasitology w Mycology w Virology Microorganisms - Microbes - Germs

5 Kingdoms of Living Organisms w 1. Animalia w 2. Plantae w 3. Fungi w 4. Protista w 5. Monera - Bacteria and Cyanobacteria w Eukaryotic vs. Prokaryotic

Difference between prokaryotic and eukaryotic cells (1/3): EukaryoticProkaryotic ExampleFungi, human cellBacteria Nuclear Material True nucleus Absent Nuclear membrane Nucleoli Multiple chromosome Single chromosome Histones associated with DNA No histone

Difference between prokaryotic and eukaryotic cells (2/3): EukaryoticProkaryotic DivisionMitosisSimple binary fission Cytoplasmic Structure MitochondriaPresentAbsent Microtubular cytoskeleton PresentAbsent Rough endoplasmic reticulum PresentAbsent Ribosome80S70S

Difference between prokaryotic and eukaryotic cells (3/3): EukaryoticProkaryotic Cytoplasmic membrane Contain sterolNo sterol (mycoplasma contains cholsesterol) No mesosomeMesosome Contain lipoprotein lipoprotein Cell wallAbsent (fungi have chitin instead) Present (except in mycoplasma)

5 Characteristics of Life w 1. Cells w 2. Maintain structure by taking up chemicals and energy from the environment w 3. Respond to stimuli in the external environment w 4. Reproduce and pass on their organization to their offspring w 5. Evolve and adapt to the environment

Taxonomic Classification w Kingdom w Phylum w Class w Order w Family w Genus w species w Escherichia coli w Non assigned for bacteria w Proteobacteria w Gamma-Proteobacteria w Enterobacteriales w Enterobacteriaceae w Escherichia w coli

Naming and Classifying Microorganisms w In a nomenclature system designed by Carolus Linnaeus (1735), each living organism is assigned two names. w The two names consist of a Genus and a species w Genus and species are either underlined or italicized

Binomial System of Taxonomic Classification w Genus species w Escherichia coli w Staphylococcus aureus w Genus is always capitilized w species is never capitilized

Classification System w 3 Domains 1978 Carl Woese 1. Bacteria Unicellular prokaryotes with cell wall containing peptidoglycan 2. Archaea Unicellular prokaryotes with no peptodoglycan in cell wall 3. Eukarya Protista Fungi Plantae Animalia

Domain Comparison BACTERIAARCHEAEUKARYA Nuclear Envelope Absent Present Membrane Organelles Absent Present Peptidoglycan Cell Wall PresentAbsent RibosomesPresent

Tree of Life

Bacterial Classification The old system of classification Based on phenotypic characteristics Bacteria were classified into: 1. Higher bacteria: a. Actinomyces (filamentous branching organism). b. Leptothrices (filamentous non branching organism).

2. Lower bacteria: Simple unicellular organisms classified on the basis of some traits as: a. Shape of the bacterial cell: cocci: spherical. bacilli: rod- shaped. Vibrios: comma- shaped. spirilla: spiral- shaped

b. Ability to form spores. c. Method of energy production: glycolysis for anaerobes cellular respiration for aerobes d. Nutritional requirements.

e. Reaction to the Gram stain It differentiates bacteria into two groups: Gram-positive bacteria (violet in color) Gram-negative bacteria (pink in color) it distinguishes between two fundamentally different kinds of bacterial cell walls.

f. Pathogenicity: Saprophytes: live on dead material, soil, water, dust... etc. They almost never cause disease. Parasites: live in the body of living creatures, they can be pathogenic or non pathogenic.

pathogenic: cause disease e.g. Mycobacterium tuberculosis Neisseria gonorrhoeae Non pathogenic (commensal bacterial flora) : Bacteria which don't normally cause diseases and can be found in healthy individuals.

The New System of Classification w The new system of classification is based on genotypic characteristics which introduce new criteria for bacterial relatedness.

Examples for new criteria introduced by genotypic characteristics 1- Nucleotide base composition: The parameter most often used is the mol percent of guanine plus cytosine (G + C) in the total DNA. For any one species, the G + C content is relatively fixed and this provides a basis for classification.

w 2- Nucleic base homology: w Organisms can be classified into groups on the basis of the homology of their DNA base sequences. w When a mixture of DNA from two related species is used, hybrid pairs of DNA strands are produced.

3 - More recently, Genome sequencing : It is nucleotide base sequences especially of their ribosomal RNA (rRNA) is being used in the classification. This technique is based on base sequence homologies in ribosomal RNA. It has provided new insights into the evolutionary relationships among the bacteria.

Bacteria - what comes to mind? w Diseases w Infections w Epidemics w Food Spoilage w Only 1% of all known bacteria cause human diseases w About 4% of all known bacteria cause plant diseases w 95% of known bacteria are non-pathogens

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

3. Microbes are used to produce Antibiotics w Penicillin w Mold Penicillium notatum w 1928 Alexander Fleming

4. Bacteria synthesize chemicals that our body needs, but cannot synthesize w Example: E. coli B vitamins - for metabolism Vitamin K - blood clotting w Escherichia coli Dr. Escherich Colon (intestine)

5. Biochemistry and Metabolism w Very simple structure w rapid rate of reproduction w provides “instant” data

6. Microbial Antagonism w Our normal microbial flora prevents potential pathogens from gaining access to our body

7. Insect Pest Control w Using bacteria to control the growth of insects w Bacillus thuringiensis caterpillars bollworms corn borers

8. Bioremediation w Using microbes to clean up pollutants and toxic wastes w 2 Genera Pseudomonas sp. Bacillus sp.

9. Recombinant DNA Technology Gene Therapy Genetic Engineering w Bacteria can be manipulated to produce enzymes and proteins they normally would not produce Insulin Human Growth Hormone Interferon

10. Microbes form the basis of the food chain w Marine and fresh water microorganisms

Koch - 1st to use Agar to solidify culture media

Golden Age of Microbiology w Pasteur Pasteurization Fermentation w Joseph Lister Phenol to treat surgical wounds – 1 st attempt to control infections caused by microoganisms w Robert Koch Koch’s Postulates w Edward Jenner vaccination w Paul Erlich 1 st synthetic drug used to treat infections Salvarsan - arsenic based chemical to treat Syphilis “salvation” from Syphilis

Naming of Bacteria w Genus and species - Binomial System of Taxonomic Classification w Information usually given: 1. Describes an organism 2. Identifies a habitat 3. Honors a scientist or researcher

Microbes do benefit us, but they are also capable of causing many diseases w PneumoniaWhooping Cough w Botulism Typhoid Fever Measles w Cholera Scarlet Fever Mumps w Syphilis Gonorrhea Herpes 1 w Chlamydia Tuberculosis Herpes 2 w Meningitis Tetanus RMSV w Strep Throat Lyme Disease AIDS w Black Plague Diarrhea Gangrene