Antibiotics, AMR and diagnostics Flashcards
What are antibiotics?
Naturally produced drugs
From penicillin mould
BActeria can be bacteriocidial or bacteriostatic. What do these terms mean?
Kill bacteria
Prevent bacterial replication
Antibiotics can be narrow spectrum or broad spectrum.What are narrow spectrum antibiotics?
Affect few bacteria - too big to penetrate gram negative outer membrane
Organism is identified and targeted
What are broad spectrum antibiotics?
Target a group of microorganisms e.g. gram positive or negative, anaerobes
For unidentified organisms
How do antibiotics work?
Prevent growth and survival of organism without damaging host- try target prokaryotic features
Target enzymes, inhibit DNA synthesis, inhibit protein synthesis, inhibit folic acid synthesis, cell wall synthesis
What is prophylaxis and metaphylaxis?
Pro - treatment given to prevent a disease
Met - mass medication given to group to try eliminate disease
What is minimal inhibitory concentration?
Minimum concentration of a drug given that inhibits bacteria growth
Does resistance develop in a pathogen during treatment?
NO
Except fluoroquinolones and rif
Resistance can be inherent or acquired. Define these terms
Inherent - natural trait
Acquired - developed by mutation or horizontal gene transfer
Plasmids can cause multi drug resistance and co selection. What is co selection?
Resistance to multiple classes of drug
PCR can be used to identify AMR genes, however what is an issue with this?
Does not show whether gene is being expressed
How do pathogens become AMR?
Outer membrane permeability decreases so drug cannot enter
Efflux of drug - drug is pumped out to decrease intracellular concentration
Target is altered so drug can no longer bind
Enzymes produced to breakdown drug (inactivation)
What is antibiotic stewardship?
Improving the use of antibiotics by decreasing use where possible
To prevent AMR
What is aetiology?
The cause of a disease/condition
What are the 3 types of methods to identify microorganisms?
Phenotypic - morphology
Immunological - serology, ELISA
Molecular - Genetics, DNA, PCR
What are the dis/advantages of using microscopes to identify a microorganism?
Not for viruses Immediate Shows number Allows presumed identification Shows host cellular response?
What is a pure culture?
A single species of organism
What test is used for the presence of metabolic enzymes?
Oxidase test
Why can some mycoses be seen under UV light by phenotypic identification
Produce fluorescent metabolites
What is a direct smear examination
Sample of faeces under a microscope to identify pathogen
How do you collect a specimen?
Collect sufficient amount from aseptic site before antimicrobial therapy
Freeze at -80 if storing
Record patient history site, sample type etc
WHat is an example of an antibiotic susceptibility testing method?
Disc diffusion
qualitative - does not show MIC
Quantitative when using dilutions of 1 antimicrobial
Viruses are obligate parasites. What does this mean?
They must grow on living cells
