Microbiology Flashcards
what is an antibiotic
a drug that kills and inhibits the growth of bacteria by interfering with the biochemistry of bacterial cells. It has no effect on viruses, but can negatively impact the beneficial bacteria in our bodies. So, the ideal antibiotic would be selectively toxic only to the bacteria that can do us harm. Because bacteria are prokaryotic cells, they are evolutionary different to our eukaryotic cells, so antibacterial target the cell structures that eukaryotic cells don’t have. This reduces side effects of the drugs.
give me an adverse effect of antibiotics
beta lactam antibiotics can cause hypersensitivity and trigger the immune response. Also, this type of antibiotic isn’t always able to distinguish between pathological bacteria and bacteria that is beneficial to us, so it can disrupt the microbiome of the gut. This can cause diarrhoea. Beta lactam antibiotics can also cause neurotoxicity as they can cross the blood-brain barrier and disrupt the inhibitory load, causing seizures.
TELL ME EVERYTHING YOU KNOW ABOUT DRUG RESISTANCE - explain the 3 ways it occurs
DRUG RESISTANCE = where microorganisms like bacteria develop the ability to defeat the drugs designed to kill them. Bacteria cells can become resistant to antibiotics in 3 ways: spontaneous mutations, acquisition of new genes, and natural selection.
Resistance due to natural selection is the idea that bacteria with an advantage will survive better against antibiotics. Antibiotics can aid the development of more advantaged strains of bacteria as they kill the less adapted bacteria, which gives the drug-resistant strains the perfect environment to grow. This happens a lot when the full course of an antibiotic isn’t taken.
Resistance due to the acquisition of new genes is the idea that bacteria can gain genetic material from other bacteria or microorganisms. For example, a bacteria can make a physical connection with another bacteria using an f-pili and pass their plasmid along. This carries genetic material, and is the way one bacterium can pass a resistant gene variant to another species or strain of bacteria. However, bacteria are preyed on by viruses, as viruses can inject their genetic code into the bacteria. This allows the virus to pick up resistant genes from the bacteria, and spread resistance to even more bacteria.
Resistance due to spontaneous mutations can happen at any time. This could be through deletions, insertions, or repeats in the DNA sequence. A genetic mutation can alter the antimicrobial target site, so the antibiotic cant bind or interact with the bacteria anymore, this usually happens to erythromycin. The membrane permeability of the bacteria can change, so it can start to reject antibiotics and not let them in. the membrane can also pump the antibiotic out. Finally, antibiotic-inactivating enzymes can destroy beta lactam antibiotics.
This type of mutation spreads through the bacterial population rapidly due to cell reproduction.
briefly descrube what drug resistance is
DRUG RESISTANCE = where microorganisms like bacteria develop the ability to defeat the drugs designed to kill them. Bacteria cells can become resistant to antibiotics in 3 ways: spontaneous mutations, acquisition of new genes, and natural selection.
describe how antibiotic resistance due to natural selection occurs
Resistance due to natural selection is the idea that bacteria with an advantage will survive better against antibiotics. Antibiotics can aid the development of more advantaged strains of bacteria as they kill the less adapted bacteria, which gives the drug-resistant strains the perfect environment to grow. This happens a lot when the full course of an antibiotic isn’t taken.
describe how antibiotic resistance due to gaining new genes occurs
Resistance due to the acquisition of new genes is the idea that bacteria can gain genetic material from other bacteria or microorganisms. For example, a bacteria can make a physical connection with another bacteria using an f-pili and pass their plasmid along. This carries genetic material, and is the way one bacterium can pass a resistant gene variant to another species or strain of bacteria. However, bacteria are preyed on by viruses, as viruses can inject their genetic code into the bacteria. This allows the virus to pick up resistant genes from the bacteria, and spread resistance to even more bacteria.
describe how antibiotic resistance due to spontaneous mutations occurs
Resistance due to spontaneous mutations can happen at any time. This could be through deletions, insertions, or repeats in the DNA sequence. A genetic mutation can alter the antimicrobial target site, so the antibiotic cant bind or interact with the bacteria anymore, this usually happens to erythromycin. The membrane permeability of the bacteria can change, so it can start to reject antibiotics and not let them in. the membrane can also pump the antibiotic out. Finally, antibiotic-inactivating enzymes can destroy beta lactam antibiotics.
compare prokaryotic cells to eukaryotic cells in terms of prokayotes cell structure
No nuclear envelope – the DNA is sat in the cytoplasm
Capsule – only some have this
Plasma membrane – similar to eukaryotic cells
Plasmid DNA – circular transmissible elements. Bacteria can swap and share this with eachother, which is how antibiotic resistance can spread as well as virus DNA
Pila – allows bacteria to clump together or adhere to other cells
Flagellum – motility.
TELL ME THE DIFFERENT TYPES OF ANTBIOTICS WHAT CAN BE USED, IN TERMS OF THE CELL WALL OF A BACTERIUM
Structural and defensive cell wall – this is a target for many antibiotic drugs, such as penicillin-like antibiotics. Gram positive bacteria have this cell wall on the outside, whereas gram negative bacteria have their cell wall between 2 membranes. Gram positive bacteria are therefore easier to attack. We can determine which type of cell wall a bacteria has as they stain differently with a dye. To kill the bacteria without cell walls, we use erythromycin.
Beta lactam antibiotics are the group of antibiotics that target the cell wall to damage the bacteria, eg penicillin. It does this by inhibiting the action of the enzyme that builds the structure of the cell wall of the bacterium (blocks cell wall synthesis). This is damaging to the bacteria because it relies on its cell wall to maintain the cell’s integrity. Without it, the bacteria will fall apart and die, which is how the antibiotic controls the population of the bacteria.
However, beta lactam antibiotics can cause hypersensitivity and trigger the immune response. Also, this type of antibiotic isn’t always able to distinguish between pathological bacteria and bacteria that is beneficial to us, so it can disrupt the microbiome of the gut. This can cause diarrhoea. Beta lactam antibiotics can also cause neurotoxicity as they can cross the blood-brain barrier and disrupt the inhibitory load, causing seizures.
Erythromycin is a type of antibiotic that blocks a crucial binding pore as well as the function of bacterial ribosomes. These ribosomes are important in bacterial cells as it translates RNA, so without ribosomes the cell dies.
briefly describe the importance of bacterium’s cell wall
Structural and defensive cell wall – this is a target for many antibiotic drugs, such as penicillin-like antibiotics. Gram positive bacteria have this cell wall on the outside, whereas gram negative bacteria have their cell wall between 2 membranes. Gram positive bacteria are therefore easier to attack. We can determine which type of cell wall a bacteria has as they stain differently with a dye. To kill the bacteria without cell walls, we use erythromycin.
describe how beta lactam antibiotics operate
Beta lactam antibiotics are the group of antibiotics that target the cell wall to damage the bacteria, eg penicillin. It does this by inhibiting the action of the enzyme that builds the structure of the cell wall of the bacterium (blocks cell wall synthesis). This is damaging to the bacteria because it relies on its cell wall to maintain the cell’s integrity. Without it, the bacteria will fall apart and die, which is how the antibiotic controls the population of the bacteria.
tell me some adverse effects of beta lactam antibiotics
However, beta lactam antibiotics can cause hypersensitivity and trigger the immune response. Also, this type of antibiotic isn’t always able to distinguish between pathological bacteria and bacteria that is beneficial to us, so it can disrupt the microbiome of the gut. This can cause diarrhoea. Beta lactam antibiotics can also cause neurotoxicity as they can cross the blood-brain barrier and disrupt the inhibitory load, causing seizures.
describe how the antibiotic erythromycin operates
Erythromycin is a type of antibiotic that blocks a crucial binding pore as well as the function of bacterial ribosomes. These ribosomes are important in bacterial cells as it translates RNA, so without ribosomes the cell dies.
define conjugation
cell to cell transfer of resistance genes
describe what pharmacogenomics is, including why its useful
the study of how gene variants occurring in a patients genome can influence how they respond to medicines. It helps to inform the best therapeutic choice. For example it can look at whether a patient carries a gene that makes them more susceptible to side effects of a drug, it can make decisions about dosing according to a patient’s metabolism, and make decisions on drug choice based whether a gene variant makes them more susceptible to an adverse reaction to a drug. Genetic variations between individuals likely drive differences in the pharmacodynamics and pharmacokinetic processes
