Chapter 10 Videos Flashcards

Question

Disruption of Cytoplasmic Membranes methods

Answer 1

* Some drugs form channel through cytoplasmic membrane and damage its integrity * Polyenes (Amphotericin B) * attaches to ergosterol in fungal membranes * Disrupting the membrane and causing lysis

Answer 2

* Antimetabolic agents can be effective when pathogen and host metabolic processes differ * Metabolic antagonists * Antimetabolic agents * Example: Sulfonomides (sulfa drugs) * They are structurally analog * As analog they compete for the active site of the enzyme for a specific pathway * Effect: termination of metabolism - cell death

Answer 3

* Several drugs block DNA replication or RNA transcription * Drugs often affect both eukaryotic and prokaryotic cells * Not normally used to treat infections * Used primarily in research and perhaps to slow cancer cell replication * Quinolones and fluoroquinolones * Act against prokaryotic DNA gyrase * Inhibitors of RNA polymerase * Reverse transcriptase inhibitors * Act against an enzyme HIV uses in its replication cycle * Do not harm people because humans lack reverse transcriptase * Examples: Nucleotide or nucleoside analogs * Interfere with function of nucleic acids * Distort shapes of nucleic acid molecules and prevent further replication, transcription, or translation * Most often used against viruses * Effective against rapidly dividing cancer cells

Answer 4

* Attachment is an essential step during the virus replication * Attachment of viruses can be blocked ther by interrupting the viral replication * Example: Attachment antagonists * Pleconaril (to treat some cold viruses)

Answer 5

* Some pathogens are naturally resistant * In nature, microbes are constantly evolving in order to overcome the antimicrobial compounds produced by other microorganisms. * Human development of antimicrobial drugs and their widespread clinical use has simply provided another selective pressure that promotes further evolution.

Answer 6

* Antibiotic resistance does not mean that your body is becoming resistant to antibiotics; * it is that bacteria (microbes) have become resistant to the antibiotics designed to kill them. * Antibiotic resistant infection are: * Difficult, and sometimes impossible, to treat * Can require extended hospital stays * additional follow-up doctor visits * costly and toxic alternatives.

Answer 7

1. New chromosomal mutations * Can be transferred vertically to subsequent microbial generations 2. Acquisition of R plasmids * via horizontal gene transfer

Answer 8

1. Lots of germs. A few are drug-resistant. 2. Antibiotics kill bacteria that cause illness, and good bacteria protect the body from infection. 3. The drug-resistant bacteria are now allowed to grow and take over. 4. Some bacteria give their drug-resistance to other bacteria, causing more problems.

Answer 9

* Microbes change or destroy the antibiotics with enzymes, proteins that break down the drug. * Example: beta-lactamase or penicillinase Once the B-lactam bond is broken, the drug loses its antibacterial activity.

Answer 10

Slow or prevent entry of drug into the cell * Microbes restrict access by changing the entryways or limiting the number of entryways. * Microbes change the structure or electrical charge of cytoplasmic membrane proteins * Example: Porins

Answer 11

Drug Binding Site Alter * Microbes change the antibiotic's target so the drug can no longer fit and do its job. * Preventing drug binding * Example: Genetic changes impacting the active site of penicillin-binding proteins (PBPs) can inhibit the binding of B-lactam drugs and provide resistance to multiple drugs within this class.

Answer 12

* By increasing the concentration of targeted enzymes * overproduce the target enzyme such that there is a sufficient amount of antimicrobial-free enzyme to carry out the proper enzymatic reaction. * By developing new cell processes that avoid using the antibiotic's target. * By absorbing its product from the environment.

Answer 13

Prevention of Cellular Uptake or Efflux * Microbes get rid of antibiotics using pumps in their cell walls to remove antibiotic drugs that enter the cell. * One single efflux pump can have the ability to translocate multiple types of antimicrobials. * Example: Efflux Pumps * actively transport an antimicrobial drug out of the cell and prevent the accumulation of drug to a level that would be antibacterial.

Answer 14

* bacteria in biofilms can resist antimicrobials * Retard diffusion of the drugs * Slow metabolic rate reduces drug effectiveness

Answer 15

* Microbes produces a protein (mimics the target) that binds to the target of an antimicrobial drug * Preventing the drugs from binding to their target. * Example: Mycobacterium tuberculosis produces MfpA protein, that binds DNA gyrase, preventing the binding of fluoroquinolone drugs

Answer 16

Multiple resistance: * Pathogen can acquire resistance to more than one drug * Resistant to three or more different drugs Cross-resistance: * Pathogen can acquire resistance to similar drugs * This occurs when drugs are similar in structure.

Answer 17

* Synergism: * One drug enhance the effect of a second drug * Use antimicrobials only when necessary * limiting usage of antibiotics in health care, agriculture industry, animal husbandry * Develop new variations of existing drugs * Search for new antibiotics, semisynthetics, and synthetics