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Chapter 28
Microbiology: Microbial Interaction with Humans
| Question | Answer |
|---|---|
| What is an organism that lives on or in another organism and causes disease? | Parasite |
| What is normal flora? | collection of microbes normally found within a healthy body |
| Pathogen | Disease causing parasite |
| Opportunistic pathogen | Causes disease in the absence of normal host resistance |
| Pathogenicity | Ability of parasite to cause disease |
| What is the quantitative measurement of an organisms ability to cause disease? | Virulence |
| Our body is not uniform describes the differences in | temperature, osmotic pressure, water availibility, nutrients, and oxygen availability |
| Epithelial cells have ___ to help wash away microorganisms | mucus. But some microbes have receptors that bind to epithelial cells and go into the cells. |
| Where can microbes grow on the outer surfaces | Moist areas like sweat glands |
| Why is skin good against microbe growth | dry and acidic |
| Eccrine glands | Main sweat glands that are responsible for thermoregulation |
| Apocrine glands | Wherever there is hair |
| Skin Flora: Transients | Organisms that don't grow but are contaminants |
| Skin flora: Residents | Able to grow on skin, most G+ Examples: Staphylococcus, corynebacteria, and P. acne |
| Mouth Protection: Lysozyme | Breaks glycosidic linkages in peptidoglycan |
| Mouth Protection: Lactoperoxidase | Produces toxic singlet oxygen and kills bacteria |
| Normal flora around teeth | Streptococci and Lactobacilli, when teeth grow in we get colonies |
| Dental plaque | Thick layer of bacteria and polymers that they secrete |
| Steps in plaque growth | 1.Deposition (settling) of glycoproteins 2.Attachment of facultative bacteria 3.Colonies form of facultative bacteria and secondary growth 4.decalcification of enamel |
| What are the facultative bacteria of the teeth? | Strepococcus sangula, S. sobrinus, S. mutans, S. mitis |
| what are the secondary growths or the teeth? | Fusobacteria and actinomyses |
| What are the two responsible bacteria causing plaque? | Streptococcus mutans and Streptococcus sobrinus |
| S. mutans | Grows in cracks/crevices between teeth. Produces a very thick glucose polymer. |
| What enzyme does S. mutans use to grow glucose polymer? | Dextransucrase |
| Helicobacter pylori | Causes stomach ulcers |
| Duodenum | Nearest the stomach, fairly acidic, similar flora of stomach |
| Jejunum and Ileum | pH is more alkaline and more bacteria; Enterococci and Lactobacilli |
| Large Intestine Facultative Enterobacteria | E. coli and Enterococcus faecalis |
| Large Intestine Obligative Anaerobes | Bascteroides, Clostridium, and long fusiform (long G- rods) |
| Bioconversions in the large intestine are responsible for | Gas and odor products |
| What are produced in the large intestine? | Vitamin B12 and K and steroids |
| Streptococcus pyogenes | Strep throat and flesh eating bacteria |
| Staphylococcus aureus | Staph infections and boils |
| Corynebacterium diptheriae | diphtheria |
| Steptococcus pneumoniae | pneumonia |
| Smoker's cough | Caused by paralysis of ciliary action by nicotine and other cytotoxins, causes accumulation of mucus and bacteria in the lower respiratory system. |
| Lactobacillus scidophilus | Colonizes the vaginal epithelium and normal flora |
| Onset of puberty in vagina causes secretions of | Glycogen and Lactobacillus |
| Tissue specificity | Organism targets specific type of tissue |
| Host Specificity | Organism only infects only a certain host |
| How is specificity of an organism possible? | Glycocalix (polysaccharides on cell surface) and fimbriae (binds to glycoproteins on cell surface- mannose) |
| Colonization factor antigen (CFA) | fimbriae-like proteins that allow organism (E. coli) to attach to the mucosa of the small intestine |
| Enteropathogenic E. coli | Have CFA's and toxins that produce diarrhea. Large intestine. |
| Transferrin and Lactoferrin | Proteins that bind tightly to iron. So if bacteria want iron they have have to have even stronger siderophores. |
| Siderophores | Iron or ferrin (Fe) binding proteins |
| Aerobactin | Plasmid that carries gene for siderophore and allows bacteria to remove iron from host |
| Localization of infection | pathogens grow locally and do not spread out |
| Bacteremia | Extensive growth in tissue happens some of he organisms can overflow into the blood |
| Septicemia | or systemic infection; continued growth and infection in the blood. |
| Virulence is determined by | toxicity and invasiveness |
| Clostridium tetani | produces a highly toxic exotoxin that makes it very virulent |
| Streptococcus pneumoniae | Highly invasive and multiplies rapidly in lung tissue |
| LD50 | Lethal dose to kill 50% of population |
| ID50 | Infectious dose to infect 50% of population |
| Virulence factors | Any extracellular proteins that are produced by pathogen and is essential for disease causing |
| Salmonella | Combines toxins, invasiveness and virulence factors to be more pathogenic |
| Cytotoxin | Substance having a specific toxic effect on certain cells |
| Enterotoxin | a cytotoxin specific for cells of intestinal mucosa |
| Endotoxin | Toxin produced by certain bacteria and released upon destruction of bacterial cell |
| Attenuation | Bacterial virulence decreases because of mutation of virulence factors (not needing them) |
| Hyaluronidase | breaks down hyaluronic acid that acts as a cell cement, and allows organisms to spread through tissue |
| Collagenase | Breaks down collagen in the tissues causing them to become loose and allows the organism to spread |
| Streptokinase | Dissolves clots and allows organism to spread- used in heart attack victims |
| Coagulase | Promotes fibrin clotting and stops defense from reaching cells |
| Hemolysis | Proteins that lyse cells (best seen in RBC) |
| Leukocidins | Lyse WBC and decrease host resistance |
| Exotoxins | Protein toxins produced and released outside of the cell. Heat sensitive. |
| Diphtheria toxin | produced by C. diptheriae. Inactivates elongation factor 2 that is required in protein synthesis in eukaryotes. |
| Phage beta in C. diptheriae | Unless incorporated into gene C. diptheriae does not produce the toxin |
| Tetanus toxin is produced by | Clostridium tetani in anaerobic wounds, potent neuortoxin by blocking the release of glycine causing spastic paralysis |
| Botulinum Toxin | Produced by clostridium botulinum, grows in food not humans, toxin kills you by blocking acetylcholine release and causes flaccid paralysis |
| Enterotoxins | Form of exotoxins in small intestine and cause massive secretion of fluid into intestine |
| Food poisoning bacteria | Staphylococcus aureus, Clostridium perfringens, and Bacillus cereus |
| Intestinal pathogens | Vibrio cholerae, enteropathogenic E. coli, and Salmonella enteritidis |
| Cholera | Diarrheal disease by cholera enterotoxin (Vibrio cholereae, G-, comma shaped) |
| Endotoxins | G- bacteria produce toxic lipopolysaccharides and are cell bound, but released when cells lyse. |
| Limulus assay | Tests for endotoxins, will lyse amoebocytes in medium |
| Specific host defenses | Against a particular organism or group of organisms |
| Nonspecific host defenses | against all pathogens |
| Tissue Specificity | Organism must colonize specific tissue to survive |
Created by:
Moessymoe
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