Infection: Antimicrobials Flashcards
What features would we want in the ideal antimicrobial?
Selective
No Adverse Effects
Needs to be able to reach the site of infection
Give it orally and IV
Have a long half life- so less has to be taken, less often
What are the 4 types of antimicrobial?
Antivirals
Antiprotozoals
Antifungals
Antibacterials
What are the 4 Classes of Antibacterial?
1) Interrupt cell wall synthesis
2) Interfere with protein synthesis
3) Interfere with nucleic acid synthesis
4) Interfere with cell membrane
Give an example of an antibacterial which targets the Cell Wall and how they work
Beta Lactams (Penicillins) - create cross linkages with penicillin binding protein which prevent it from catalysing cross linkages to create a new cell wall
Penicillin: Main against Streptoccoci
Amoxicillin: Gram Negative
Glycopeptide (Vancomycin) - use in gram positive only, prevents cross linkages in cell wall by binding on to the end of peptides
Give an example of an antibacterial which targets protein synthesis
Tetracyclines- interfere with enzyme stages
Broad Spectrum and Oral only
Good against atypical pathogens in pneumonia
Aminoglycosides- (-micins) good against Gram Negative (sepsis)
Can be nephrotoxic
Macrolides- often used instead of Penicillin
Sulphonamides- Inhibit synthesis of Folic Acid
Trimethoprim- used in UTIs
Both treat PCP and MRSA
Give an example of an antibacterial which targets nucleic acid synthesis
Quinolones- prevent coiling of nucleic acid, by inhibiting DNA Girase
What is conjugation?
Direct bacteria to bacteria gene transfer
What is transformation?
Free DNA enters the bacteria
What is transduction?
DNA from Bacteriaphages
Describe Chromosomal Gene Mutation
One bacterium gets a random mutation, when a drug is used, it is found to be resistant, it can divide and creates a resistant population
What are some risk factors of CG Mutation?
Not completing the course
If there was previous exposure
Not a high enough dose of drugs
Resistance: Describe drug inactivation
Enzymes are produced by bacteria.
Usually adds an acetyl or phosphate group which means it cannot bind as well to bacterial ribosomes/protein syntheisis
Resistance: Alteration of Target
Change their binding site which lowers the drug affinity
Resistance: Altered Uptake
Either decrease permeability through the wall or increase efflux, tetracycline, drug is forced out before its effect
Give examples of Antifungals
Polyenes - inhibit cell membrane function, topical treatment for candida
-Azoles - vs yeasts and moulds, inhibit membrane synthesis
