Lecture 291. Know the meaning of loose association, adhesion, and colonizationa. Loose association- come close to mucus but not actually touching the cellsb. Adhesion- the cells come in contact and bind with epithelial cellsc. Colonization- The growth of microbes found at any anatomical sitei. Commonly occurs on mucus membranes, outer layer of epithelia cells that are on the surface of many tissues2. Where are epithelial cells found and what are mucous membranes a. Epithelial cells are found on the outside of separate body cavities facing the lumenb. Mucus membrane- outer layer of epithelial cells that are on the surface of many tissues3. Describe what nutrients are provided on certain skin areas a. Waterb. Amino acidsc. Uread. Saltse. Fatty acids4. Know what environmental stresses microbe have in some skin areas a. Bacterial interference- where no pathogens can inhibit or preventgrowth of pathogens5. Understand why different skin locations have different composition of microbial phyla a. Different parts of the human skin are moist, dry, see sunlight, don’t see sunlight. Some area have sebaceous glands6. Know what anti-microbial enzymes are in saliva and how they protect against some bacteria a. Lactoperoxidase- Makes a reactive species (hypothiocyanate; OSCN) as a product- kills bacteriab. Lysozyme- Enzyme that cleaves peptidoglycan7. Describe the step leading to formation of plaque and tartar a. Begins as layer of glycoprotein on surface of clean toothb. Attachment and colonization by several bacteria that grow into a biofilmc. Continued growth results in thick layer called plaqued. Plaque becomes calcified, resulting in tartar8. Compare dental caries and gingivitis and the role microbes play in development oxf these diseases a. Dental Caries- Occurs when anaerobic microbes in an oral biofilmferment dietary sugars and produce acidsi. The lactic (and other acids) produced by the microbes demineralizes tooth enamelb. Gingivitis is an infection of the gingival crevicei. Infection leads to tissue inflammation and underlying bone loss9. Know how pH and oxygen affect microbial populations and how the stomach acts as a barrier to pathogen entry a. As food travels down the GI tract, the pH gradually changes from acidic to neutral and oxygen is quickly consumed (most of the tract is anaerobic)i. Bacterial populations go from a few in the stomach to around 500 phylotypes in the large intestine. 10. Describe where Helicobacter is found and what disease it causes a. Lives within the mucus lining of the stomachb. Colonization and production of various extracellular factors by H. pylori cells results in tissue damage and the formation of unclers11. Understand in a general way how microbial populations and diversity change as food moves through the intestinal tract a. Less acidicb. More anoxicc. Higher microbial abundanced. Higher microbial diversitye. Small and large intestines provide environments for beneficial microbes that aid the nutrition of their host.12. Describe the locations of the upper and lower respiratory tract and where microbes can be found a. Upper- Sinuses, nasopharynx, pharynx, oral cavity, and larynx) is colonized by many microorganismsi. Normal microflora antagonize pathogens from growingii. In some individuals, pathogenic bacteria are present but do not cause diseases1. Known as carriers b. Lower respiratory tract (trachea, bronchi, lungs) is sterile in healthy individuals13. Know the bacterium that colonizes the vagina and what role it has in protecting against pathogensa. Lactobacillus acidophilus, ferments glycogen and produce acid, creating a pH 5 environment that inhibits most bacteria and pathogens14. Be able to describe the steps involved in pathogenesis, leading from exposure to tissue damage a. Microbial Pathogenesisi. Initiated by exposure of a host to a pathogenii. Adherence to skin or mucosaiii. Invasion through epitheliumiv. Infection- growth and production of virulence factors and toxinsv. Can result in toxicity (toxin effects are local and systemic) or invasiveness (further growth at original distant sites)vi. Tissue damage, disease15. Define an opportunistic pathogen a. Can cause disease because the normal resistance mechanisms of a host are weakened.16. Define virulence, what virulence factors are a. Virulence- A measure of pathogenicity that can be determined in animal modelsb. Virulence factors- Enable a host to replicate and disseminate within a host in part y subverting or eluding host defenses.17. Know the meaning of ID50 and LD50 and how virulence is quantitated a. Can measure virulence by exposing populations of test animals to increasing doses of a bacterial pathogen. b. ID50- infective does that makes 50% sickc. LD50- lethal dose that kills 50% of population18. Know what adherence factors are and how they aid virulence a. The attachment of microoganisms to host tissuesi. Adherence is aided by adherence factorsii. Adherence is usually specific: tissue
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