Pathology - Antibiotics History Flashcards
Antimicrobial Resistance
When microorganisms evolve to evade antibiotic effects through various mecahnisms
What does Antimicrobial Resistance refer to?
Microorganisms adapt from medications once impacting them to a state they’re resistant.
What are examples of Antibiotics mechanism of action?
Inhibit cell wall synthesis
Interfer with membranes permeability
Inhibitiion on ribosome subunits
Blockage of metabolic steps
Inhibition of nucleic acid synthesis
Intrinsic Resistance
Resistance by a naturually occuring feature typical of bacteria.
Example of Intrinsic Resistance?
Streptococci lack nitroreductases that convert metronidazole to active state required for its activty.
Mutational Resistance
Generational or spontaneous chromosmal mutations, producing resistant strains through naturual selection.
Acquired Resistance
Horizontal acquistion from other microorganisms encoding for genetic resistances through conjugation, transduction and transformation.
Transduction
Translocation of DNA from bacterium to another, utilising bacteriophages
Transformation
Where bacteria acquire DNA segments within the environment.
Alexander Fleming
A bacteriologist whom discovered bacteria when a petri dish containing staphylococci on a bench got contaminated by a fungus affecting growth of nearby bacteria
What fungus inhibited bacterial growth?
Penicillium Notatum
What happened in 1939 after Flemings Discovery?
Howard Florey and Ernst Chain designed a method to culture fungu and produce it to test its antimicrobial abilities.
What was the first experimental test of Penicilllum Notatum?
Injection of mice with fatal doses of streptoccous then treatment with the fungus with surivval rates.
How does penicillin exert its effects?
Upon highly conserved PG cell wall
What is the structure of penicillin
Contains a Beta-Lactam Ring, a Thiazoldine Ring and a 6-Aminopenicillinanic Acid Side chain.
Beta-Lactam Ring
A four membered ring inhibiting transpeptidase by mimicking two of D0alanine of the peptide with irreversible binding to PBP.
Why does Beta-Lactam binding to PBP result in?
Inability of PG cross-linking making cell susceptible to lysis.
Penicillin
A molecule with a beta-lactam based ring
How do Penicillin generations differ from one another?
Different chemical residues with different functions attached to the beta lactam ring
What is an example of the diversity of Penicillins?
Benzylpenicillins are more active against GPB of cocci and bacilli shape, not so effective against GNB
Why are penicillins commonly poor against GNB?
Occurence of OM and ability to produce beta-lactamases.
Beta-Lactamases
Bacteria produced enzymes giving multi-resistance capabilties to beta-lactam antibiotics.
What are some sescond generation penicillins?
Oxacillin, Methicillin and dicloxacillin.
Anti-Staphylococcal Antibiotics
A class of second generations beta lactams used to treat bacterial infections
Aminopenicillins
Third generation group of antibiotics with additional amin groups enhancing antibacterial activity.
When did the first penicillin resistant bacteria develop?
E.Coli in 1940 producing penicillinase
How many S.aureus species were resistant to penicillin by 1960?
80 percent.
What is an example of early mechanisist resistance against penicillin?
1981 methicillin resistant chains altered original PBP to PBP-2a with reduced affinity.
What does ROS do in bacteria?
Induce oxidatitve stress, affects Na/K ATPase pumps etc.
How might genetically engineered E.Coli provide Antibiotic alternatives?
They can secrete antimicrobial peptides in response to quorum sensing molecules
Phage Therapy
Uttilises bacteriophages to target specific bacteira.
What are some alternatives to antibiotics?
Phage Therapy
Metal Nanoparticles
Genetically Engineerd E.Coli
Hygeine
