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Microbiology Chap 10
Controlling Microbial Growth in the Body: Antimicrobial Drugs
| Question | Answer |
|---|---|
| Chemotherapeutic agents | drugs that act against diseases |
| Antimicrobial agents | drugs that treat specific infections |
| Penicillium mold | produces a substance that kills gram-positive bacteria |
| Alexander Fleming | Discovered Penicillin is released from Penicillium |
| Semisynthetics | natural, but chemically altered antibiotics that are more effective than naturally occuring ones |
| Synthetic | antimicrobials that are completely synthesized in a lab |
| Antibiotics | products of or derived from living microorganisms |
| Selective toxicity | a drug should harm the <b>pathogen</b> but not the host |
| Most common agents prevent | cross-linkage of NAM subunits |
| Inhibition of bacterial cell wall synthesis | *Most common agents prevent cross-linkage of NAM subunits *Beta-lactams =most prominent in this group -functional groups are beta-lactam rings -beta-lactams bind to enzymes that crosslink NAM subunits *Bacteria have weakened cellwalls& eventually lyse |
| Semisynthetic derivatives of beta-lactams | *More stable in acidic environments *More readily absorbed *Less susceptible to deactivation *<b>More active against more types of bacteria (altered spectrum)</b> |
| Inhibition of synthesis of bacterial walls | *Prevent bacteria from increasing amount of peptidoglycan *Have no effect on existing peptidoglycan later <b>*Effective only for growing cells</b> |
| Quinolones & fluoroquinolones | active against prokaryotic DNA gyrase |
| Prevention of Virus Attachment | *Attachment antagonists block viral attachment or receptor proteins *New area of antimicrobial drug development |
| Routes of Administration *Topical *Oral route *Intramuscular *Intravenous | *Topical application of drug for external infections (Neosporin) *requires no needles and is self-administered (pills or liquid) |
| *Intramuscular *Intravenous | *intramuscular administration delivers drug via needle into muscle (inject in muscle) *intravenous administration delivers drug directly to bloodstream (IV, usually = hospitalization) |
| Toxicity | -adverse effect usually on organ *cause of many adverse reactions poorly understood *drugs may be toxic to kidneys, liver, or nerves *Consideration needed when prescribing drugs to pregnant women |
| Allergies | *Allergic reactions are rare but may be life threatening *Anaphylactic shock (life threatening allergi reaction, happens quickly) |
| Oral candidiasis (thrush) | involves white curd-like growth on the mucous membrane of the mouth |
| Resistance by bacteria acquired in two ways | *new mutations of chromosomal genes (lower probability) *Acquisition of R-plasmids via transformation, transduction, and conjugation (rapid spread through bacterial populations) |
| At least 6 methods of microbial resistance | *Produce enzyme that destroys or deactivates the drug *Slow or prevent entry of drug into the cell *alter target of drug so it binds less effectively |
| At least 6 methods of microbial resistance (cont.) | *alter their metabolic chemistry *pump antimicrobial drug out of the cell before it can act *biofilms retard drug diffusion & slow metabolic rate |
| *Pathogen can acquire **Common when | *resistance to more than one drug **R-plasmids exchanged |
| Slowing down development of resistance: | <b>*use antimicrobials only when necessary</b> *develop new variations of existing drugs *search for new antibiotics, semisynthetics, and synthetics |
Created by:
jklemz
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