ER - Antibacterials & Drug Efflux Flashcards
What are antimicrobials?
Medicines used to prevent and treat infections caused by microorganisms in humans, animals and plants
What is antimicrobial resistance?
When the microorganisms change or mutate over time and get to a point where they no longer respond to medicines previously used to treat them
What are the informal bacterial groups based on Gram staining? (4)
- Gracilicutes (Gram-negative): Photobacteria (photosynthetic) & Proteobacteria (non-photosynthetic)
- Firmicutes (Gram-positive)
- Mollicutes (Gram-variable), e.g. Mycoplasma
- Mendocutes (uneven Gram stain; “methanogenic bacteria,” now known as Archaea)
What are the differences between Gram-negative, Gram-positive, and mycobacteria cell walls?
- Gram-negative bacteria: Thin peptidoglycan layer in periplasmic space between inner and outer lipid membranes, with lipopolysaccharide (LPS) on the surface
- Gram-positive bacteria: Thick peptidoglycan layer and lipoteichoic acid, anchored to a single lipid membrane by diacylglycerol
- Mycobacteria: Thin peptidoglycan and arabinogalactan layers with a thick mycolic acid layer surrounding a single lipid membrane
What are some basic characteristics of bacterial cell structure? (3)
- No nucleus or membrane-bound organelles
- Due to their rigid cell wall, bacteria maintain definite shapes
- Common shapes include bacillus (rod), coccus (sphere), and vibrio (spiral)
also filamentous, box-shaped, appendaged and pleomorphic bacteria
What is the ESKAPEE group of antibiotic-resistant bacteria?
Enterococcus faecium (Gram-positive; spherical; facultative anaerobe)
Staphylococcus aureus (Gram-positive; spherical; facultative anaerobe)
Klebsiella pneumoniae (Gram-negative; rod-shaped; facultative anaerobe)
Acinetobacter baumannii (Gram-negative; round/rod-shaped; aerobic)
Pseudomonas aeruginosa (Gram-negative; rod-shaped; aerobic-facultatively anaerobic)
Enterobacteriaceae (Gram-negative; rod-shaped; facultative anaerobe)
Escherichia coli (Gram-negative; rod-shaped; facultative anaerobe)
What does the term “facultative anaerobe” mean?
Organisms that make ATP by aerobic respiration if oxygen is present but can switch to fermentation if oxygen is absent
Why is the ESKAPEE group particularly dangerous? (2)
- They are highly virulent
- Can escape commonly used antibiotics due to increasing multi-drug resistance (MDR)
What is the Common ‘Pool’ Problem? (2)
Common ‘pool’ problem
* Production of antibiotics is slowing - insufficient funding, less academic research, clinical research is challenging, limited markets.
- Resistance is increasing - Overuse in treatment, inappropriate use of treatment, environmental pollution, inappropriate use in agriculture
How does antimicrobial resistance happen? (4)
- Lots of germs and some are drug resistant
- Antibiotics kill the bacteria causing the illness as well as the good bacteria protecting the body from infection
- The drug resistant bacteria is now able to grow and take over
- Some bacteria also give their drug resistance to other bacteria (transduction, conjugation, transformation)
What are mobile genetic elements? (3)
Plasmids: Circles of DNA that can move between cells.
Transposons: Small DNA segments that can insert into and change the DNA of a cell.
Phages: Viruses that transfer DNA between bacteria.
How do mobile genetic elements spread antibiotic resistance genes?
Transduction: Phages transfer resistance genes between bacteria.
Conjugation: Resistance genes are exchanged when bacteria physically connect.
Transformation: Bacteria pick up resistance genes from nearby live or dead bacteria.
What are some methods bacteria use to develop antimicrobial resistance? (4)
- Downregulating porins to prevent antibiotics from entering the cell
- Efflux pumps to remove antibiotics from the cell
- Generating enzymes to inactivate antibiotics
- Protecting target proteins from antibiotics
What is a biofilm and how does it form? (5)
A structured community of bacteria and other microorganisms that attach to a surface and produce a protective, sticky matrix of extracellular polysaccharides
1. Reversible attachment of planktonic cells (seconds)
1. First colonisers become irreversibly attached (seconds, minutes)
1. Growth and cell division (hours, days)
1. Production of extracellular polysaccharide matrix (EPS) and formation of water channels (hours, days)
1. Attachment of secondary colonisers and dispersion of microbes to new sites (days, months)
How do biofilms protect bacteria?
The EPS matrix entraps bacteria and creates channels that protect the internal environment while facilitating nutrient delivery and waste removal
