Micro control in body Flashcards
Importance of normal microflora
they inhibit binding of pathogens, decrease nutrient availability, actively kill pathogens, stimulate our immune system
“Magic Bullet”
ideal antibiotic. Paul Ehrlich.
Methods of action of antimicrobials
Inhibit cell wall, protein, plasma membrane, metabolic pathways, DNA or RNA, attachment to host
Inhibit cell wall synthesis
Penicillin blocks NAG and NAM crosslinking, so cell wall will burst in because they have no wall. Only effective if cell is dividing
Inhibit protein synthesis
Block binding of 30S of 50S subunit, stop a.a. coming in, inhibit elongation
Disrupt cytoplasmic membrane
For fungi (eukaryotes); attaches to unique sterols in membrane and makes pores
Inhibit metabolic pathways
inhibit enzymes; best is noncompetitive
Ideal antimicrobial agent
Readily available (easy to make or isolate), Inexpensive, Chemically stable, Easily administered, Nontoxic and nonallergenic, Selectively toxic against wide range of pathogens (and not to humans)
Evaluation
Spectrum of action (target), Efficacy, Bioavailability, side effects, selective toxicity
Efficacy of antimicrobial
Dosage(s) required, route of administration, overall safety
Problem with minimum inhibitory concentration test and solution
Don’t know if it’s bacteriostatic or bactericidal; run a minimum bactericidal concentration test: plate a clear MIC tube to see CFUs
Septocemia and solution
Causes huge inflammatory response in the blood. Requires high level of antibiotic immediately
Side effects of antibiotics
Toxicity (of it or of metabolites), Allergies, Disruption of normal microbiota
Toxicity of antibiotics
Causes not well understood; genetics; some are toxic to nerves, liver, or kidneys; considerations for pregnant women; combination of meds
Allergic reactions to antibiotics
Some are not allergic but are produced by something else
Disruption of Normal microbiota
Can cause secondary infection; if pathogens overtake normal microbiota can cause superinfections; concern in hospitals
Development of Resistant Organisms
Acquired by mutation of their own DNA, plasmids, or horizontal gene transfer (transduction, transformation, conjugation)
Mechanisms of resistance to antibiotics
Production of enzymes (inactivate it), Slow or prevent entry of the drug (but DNA leaks from dying cells), Alter the receptor for the drug, Alter metabolic chemistry, Multi-drug efflux pumps
Satellite colonies
Colonies that grow near a colony that secretes enzymes against an antibiotic - they are saved
What can occur with the constant use of drugs?
it kills all the sensitive cells, but selects for superbugs (mutate frequently/insensitive), cross resistance (horizontal gene transfer)
Retarding resistance
High [ ] for a long enough time, new variations of drugs, not too many antimicrobials, combination therapies
