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2. CHAPTER 1 The Background of Microbiology
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3. Introduction
Microbiology: study of organisms that cannot be seen by gross examination
Microscope is needed
Three types of microscopes
Basic compound microscope
Scanning electron microscope
Confocal laser microscope
(Continues)
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4. Introduction Microorganisms Abundant in/on the body
Many are beneficial (normal flora)
Few cause disease (pathogenic)
Increased ability to produce an infection (virulence)
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5. Classifications of Microorganisms
According to cell type
Protists (one-celled organisms)
Two groups
Prokaryotes (e.g., bacteria, mycoplasmas)
Eukaryotes (e.g., animals, plants)
(Continues)
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6. Eukaryotes and Prokaryote

7. Classifications of Microorganisms
Unclassified microorganisms include
Viruses
Incapable of reproducing on their own
Require a host cell
For example, measles, HIV, common cold
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8. Infectious Proteins Prions Do not fit any cellular category Anucleate
Cause CNS infections
Lack nucleic acid
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9. Eukaryotes Cell membrane Nucleus Outer layer; selectively permeable
Protects; provides passage for nutrient/waste
Nucleus
Control center
Contains DNA
(Continues)
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10. Eukaryotes Cytoplasm Nucleolus Ribosomes Maintains cell shape
Within the nucleus
Needed for protein manufacture
Ribosomes
Site of protein synthesis
Contain RNA
(Continues)
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11. Eukaryotes Mitochondria Golgi apparatus Lysosomes Powerhouses
Store energy in the form of ATP
Golgi apparatus
Combines CHO with proteins
Lysosomes
Synthesized in ER
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12. Prokaryotes Contain Cell membrane, cell wall No nucleus (anucleate)
Nucleoid for storing DNA
Capsule of slime layer to increase resistance to antibacterial agents
(Continues)
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13. Prokaryotes
Cilia (short, fine filaments that move fluid over a surface)
Flagella (long filaments that provide motility for the cell)
Spores (hard outer wall produced by inactive bacterial cells)
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14. Normal Flora versus Pathogens
Exist on, in, or around us; may become pathogenic if they do not remain in intended location of the body
Most prevalent in areas open to the outside
Not found in blood or CSF
Pathogen
Capable of causing disease
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15. Immune System Three lines of defense Protective barriers
Circulatory or bloodstream response
Innate, adaptive response
Phagocyte Neutrophil Monocyte
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16. Protective Barriers Intact skin and its secretions
Respiratory tract (e.g., mucus, sneezing)
GI tract (e.g., saliva, acidic pH of stomach)
GU tract (e.g., expulsion of urine)
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17. Circulatory and Bloodstream Response
Phagocytes (phag/o = to eat)
Neutrophils, monocytes, macrophages, dendritic cells
Lysosomes
May be in fixed locations (e.g., bone marrow, liver) or may roam to location of foreign substance
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18. Innate Immune Response
Exists at birth
Is not pathogen specific
Does not require previous exposure
Kills invading microbes
Begins inflammatory response (redness, swelling, and pain)
Alerts adaptive immune response
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19. Innate/Adaptive Immune Response
Antigen presenting cells (APCs)
Macrophages and dendritic cells kill microbes
Present intruding microorganisms to T cells
Antigen
Marker recognized as foreign
Phagocytic cells engulf pathogen, presenting fragments on its surface, notifying the adaptive immune system of invader
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20. Adaptive Immune Response
Cellular mediated
Recognizes pathogen
Activates T cells (which secrete cytokines)
Humoral response
T cells interact with B cells that produce antibodies (immunoglobulins)
Antibodies destroy antigen
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21. Infection Caused by invasion by microbe Localized or generalized
Virulence determined by
Cell structure
Production of endotoxin (contained within the microbe) or exotoxin (produced by and secreted by the microbe)
(Continues)
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22. Infection

23. Infection Most common disease-causing microorganisms in humans
Bacteria
Viruses
Fungi
Parasites
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24. Bacteria, Virus, Fungi, Parasites

25. Direct and Indirect Disease Transmission
Contact transmission
Direct contact (with the person)
Indirect contact (with fomite, vector, common vehicle, or airborne droplets)
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26. Fever and the Inflammatory Response
Infection accompanied by
Fever
Assists in clearing infections
Important defense mechanism
Inflammation
Part of the innate immune response
Caused by dilatation of blood vessels
Infiltration of infected site by antibodies and WBCs results in death of the microbe
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27. Summary Classification of microorganisms Normal flora Pathogens
Prokaryotic
Eukaryotic
Normal flora
Live on/in body
Pathogens
Cause disease
(Continues)
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28. Summary Immune system response Pathogenicity Virulence Innate Adaptive
Cellular: activates phagocytes, T-cells, release cytokines
Humoral: a person not previously infected, B-cells will produce antibodies
Pathogenicity
Ability of microbes to cause disease
Virulence
Strength of disease-causing microbe
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