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2. CHAPTER 1 The Background of Microbiology 1-2

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) 1-3

4. Microorganisms –Abundant in/on the body –Many are beneficial (normal flora) –Few cause disease (pathogenic) –Increased ability to produce an infection (virulence) Introduction 1-4

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) 1-5

6. Classifications of Microorganisms Unclassified microorganisms include –Viruses Incapable of reproducing on their own Require a host cell For example, measles, HIV, common cold 1-6

7. Infectious Proteins Prions –Do not fit any cellular category –Anucleate –Cause CNS infections –Lack nucleic acid 1-7

8. Eukaryotes Cell membrane –Outer layer; selectively permeable –Protects; provides passage for nutrient/waste Nucleus –Control center –Contains DNA (Continues) 1-8

9. Eukaryotes Cytoplasm –Maintains cell shape Nucleolus –Within the nucleus –Needed for protein manufacture Ribosomes –Site of protein synthesis –Contain RNA (Continues) 1-9

10. Eukaryotes Mitochondria –Powerhouses –Store energy in the form of ATP Golgi apparatus –Combines CHO with proteins Lysosomes –Synthesized in ER 1-10

11. Prokaryotes Contain –Cell membrane, cell wall –No nucleus (anucleate) –Nucleoid for storing DNA –Capsule of slime layer to increase resistance to antibacterial agents (Continues) 1-11

12. 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) 1-12

13. Normal Flora versus Pathogens Normal flora –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 1-13

14. Immune System Three lines of defense –Protective barriers –Circulatory or bloodstream response –Innate, adaptive response 1-14

15. 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) 1-15

16. 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 1-16

17. 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 Innate Immune Response 1-17

18. 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 1-18

19. 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 1-19

20. 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) 1-20

21. Infection Most common disease-causing microorganisms in humans –Bacteria –Viruses –Fungi –Parasites 1-21

22. Direct and Indirect Disease Transmission Contact transmission –Direct contact (with the person) –Indirect contact (with fomite, vector, common vehicle, or airborne droplets) 1-22

23. 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 1-23

24. Summary Classification of microorganisms –Prokaryotic –Eukaryotic Normal flora –Live on/in body Pathogens –Cause disease (Continues) 1-24

25. Summary Immune system response –Innate –Adaptive Cellular Humoral Pathogenicity –Ability of microbes to cause disease Virulence –Strength of disease-causing microbe 1-25