Chapter 5

1. Chapter 5 Microbiology

2. Learning Outcomes • 5.1 Identify microorganisms including bacteria, viruses, fungi, and protozoa. • 5.2 Recognize terminology used in relation to the growth of microbes. • 5.3 Recall the different types of microbes and the role they play in the cycle of infection. • 5.4 Describe how to prevent or control microbial growth and the spread of infection.

3. Microorganisms • Bacteria – prokaryotic cells that vary widely in size, shape, and cell arrangement; visible with a light microscope • Bacilli – rod shaped • Cocci – spherical • Spirilla – spiral shaped • Diplococci – paired spherical • Streptobacilli – chains of rod-shaped bacteria • Coccobacilli – short, thick, ovoid rods

4. Bacterial Shapes and Arrangements

5. Microorganisms • Bacterial Staining Characteristics • Gram’s stain • Gram-positive – stain blue (retain the stain) • Gram-negative – stain red (do not retain the stain) • Organisms that are hard to stain using Gram’s stain • rickettsia • mycoplasma • treponema • chlamydia • mycobacteria • Legionella pneumophilia

6. Microorganisms • Intermediate organisms – obligate intracellular parasites • Rickettsia • Chlamydia • Mycoplasma • Mycobacterium • Legionella pneumophilia

7. Microorganisms • Viruses • DNA or RNA wrapped in a protein coat • Visible only with an electron microscope • Viron – virus that exists outside a host cell • Bacteriophage – virus with a bacterial host

8. Microorganisms • Fungi – eukaryotic organisms with cellulose or chitin cell walls • Mushrooms • Molds • Yeasts • Protozoa – unicellular eukaryotic organisms of diverse types, once believed to be the lowest forms of animal life

9. Microbial Growth • Growth that is dependent on source of energy and nutrient chemicals; influenced by temperature, pH, moisture content, available nutrients. • Fermentation • Respiration • Photosynthesis • Aerobe • Anaerobe

10. Microbial Growth • Nutritional Types • Heterotrophs – organisms that obtain carbon from organic material • Autotrophs – organisms that use inorganic carbon dioxide as their basic carbon source • Chemotrophs – organisms that use chemical substances as a source of energy • Phototrophs – organisms that use light as a source of energy

11. Microbes and the Human Body • Medical microbiology – study of pathogens and the disease process • Normal (resident) flora – bacteria that are permanent and beneficial residents in the human body

12. Microbes and the Human Body • Host – an organism in which another organism is nourished and harbored • Symbiosis • Mutualism • Commensalism • Parasitism

13. Microbes and the Human Body • Pathogens – disease causing microorganisms • Pathogenicity • Virulence • Infective dose • Contagious disease • Vector • Resistance

14. Microbial Control and Asepsis • Microbial control – prevention of infectious disease using heat, steam, fire, and chemicals to control microbial growth • Asepsis – the condition in which pathogens are absent or controlled • Medical asepsis – procedures used to reduce the number of microorganisms and prevent their spread (clean technique) • Surgical asepsis – elimination of all microorganisms from objects or working areas (sterile technique)

15. Infectious agent Susceptible host Reservoir host Means of entry Means of exit Mode of transmission The Cycle of Infection

16. Microbial Control and Asepsis • Sanitization – reduction of the number of microorganisms • Disinfection – process of removing or killing pathogens (except for spores) • Bactericidal – destructive to bacteria • Bacteriostatic – inhibiting the growth of bacteria • Antisepsis – inhibition of bacterial growth