Microbiology: Antimicrobial Drugs and Infection - Prof. Charlotte L. Powers, Study notes of Microbiology

Download Microbiology: Antimicrobial Drugs and Infection - Prof. Charlotte L. Powers and more Study notes Microbiology in PDF only on Docsity! HSCI 2230 Introduction to Microbiology Spring 2010 Powers Set 2 terms - narrow spectrum agents toxemia broad spectrum agents intoxication selectively toxic necrosis true pathogen localized, systemic, focal infections antigens opportunistic pathogen mixed infection antibodies virulence factors primary & secondary infections chemotaxis sequelae acute, chronic, subacute infections etiologic agent signs, symptoms fomite virulence factors lysosome Chapter 12 1. How many children died of an infectious disease before age 5 in the early 1900s? 1 out of 3 2. Study Table 12.1 characteristics of the ideal antimicrobial drug. Selectively toxic to microbe not host, microbicidal rather than microbistatic, soluble & functions when highly diluted in body fluids, remains potent & isn’t broken down or excreted prematurely, resistant organisms don’t develop, aid host’s defenses, remains active, readily delivered to site of infection, not expensive, and doesn’t cause allergies. 3. Where do most antibiotics come from? What is the natural function of antibiotics? Bacteria in genera Streptomyces and Bacillus; molds in the genera Penicillium and Cephalosporium. Helps compete. 4. What are 4 mechanisms of antimicrobial drug action? Inhibit cell wall synthesis*, inhibit nucleic acid synthesis/function, inhibit protein synthesis, and disrupt cell membrane function. 5. Know how 1) penicillin, 2) vancomycin, 3) zithromax and 4) amoxillcillin work. (1,2,4)*Block synthesis and repair; (3) act upon ribosome and block protein synthesis. 6. What is competitive inhibition? Drug mimics natural substrate of enzyme & competes for active site. 7. List 2 genetic events that cause microbes to become resistant to drugs. Chromosomal mutations and transfer of DNA from a resistant organism. 8. Explain 4 general mechanisms of drug resistance. Synthesis of enzymes that inactivate the drug, decrease uptake of drug, changes in drug targets, and changes in metabolic pathways. 9. Why are there so few antifungal, antiparasitic, and antiviral drugs? Difficult to achieve selective toxicity with eukaryotic pathogens because they are so similar to human cells. Viruses are difficult to target because they grow inside of cells and we have to really understand how they replicate to block their specific processes. 10. What are 3 adverse effects of antimicrobic drugs on the host? Toxicity—direct damage to tissues; liver, kidneys Allergic reactions—most commonly from penicillins Disruption of normal flora—allows for a superinfection or overgrowth of fungi Chapter 13 11. What is the difference between infection and disease? Infection—invasion or colonization of the body by pathogens, presence of pathogens in the body Disease—when the growth of pathogens damages all or part of the body so that it is incapable of performing normal functions. 12. Where do you find normal flora? Skin, upper respiratory tract, most of GI tract, outer opening of urethra, & vagina. 13. Which sites of the body are microbe-free? All internal tissues and organs; fluid within an organ or tissue. 14. List several factors that predispose a person to disease. Old age & extreme youth, genetic defects in immunity, AIDS, surgery & organ transplants, diseases (cancer, diabetes), physical & mental stress, and other infections. 15. List 3 portals of entry. Skin, mucous membrane, and parenteral. 16. Describe an infectious dose. Number of microbes required to initiate an infection; it usually takes more than one microbe to start an infection. 17. List several mechanisms of adherence. Fimbrae, capsules, spikes, hooks, and flagella. 18. List several examples of exoenzymes and their activities. Mucinase—digests protective coating of mucous membranes; hyaluaronidase—digests hyaluaronic acid, which cements cells together; coagulates—causes blood clots; kinases—break clots. 19. What is the difference between exotoxins and endotoxins? Exotoxins: secreted by gram + and – cells, chemical composition is protein, destroyed at 80C, and has various effects on specific cell structure. Endotoxins—part of gram – cell wall, chemical composition is lipid A of LPS, withstands autoclave, and produces fever, weakness, aches & shock. 20. What are the 4 periods of disease and what occurs during each? Incubation period—time from initial contact with microbe; microbe multiplies; Prodromal stage—microbe multiplies, appearance of first symptoms; Period of invasion—microbe multiplies to high levels, exhibits great toxicity, becomes well established in target tissue; Convalescent period—more are cleared, recovery.