Antibiotics

Question 1

what do you need for bacteria to grow

Answer 1

nutrients

appropriate physical and chemical environment

Question 2

4 stages of bacterial growth graph

Answer 2

lag phase - active and growing and if nutrients plentiful go to log
log/exponential phase
stationary phase - build up waste produces promote cell death
death phase

Question 3

what features do you look for in a good antibiotic

Answer 3

effective 
safe 
slow emergence of resistance 
long half life 
good tissue distribution 
oral bioavailability 
cheap

Question 4

what ribosomes do bacteria have

Answer 4

70S

Question 5

can antibiotics halt exponential growth giving chance for immune system to bring it down or be bacterialcidal and deplete them cause them to rupture

Answer 5

yes

Question 6

name an aerobic bacteria

Answer 6

gram negative neisseria.spp

Question 7

name an anaerobic bacteria

Answer 7

clostridium.spp gram postiive

Question 8

what are staphcoccus, strept, listeria, klebseilla, e coli all examples of

Answer 8

facultative anaerobes - replicate in aerobic but cn switch if conditions dictate it

Question 9

what are the 5 classifications of antibiotic mode of action

Answer 9

Inhibition of cell wall synthesis 
metabolic antagonism 
interference with nucleic acid synthesis 
inhibition of protein synthesis 
action on membrane

Question 10

what type of cell wall does bacteria have

Answer 10

Peptidoglycan ( N-acetylglucosamine and N-acetylmuramic acid amino acid crosslinked)

Question 11

examples of antibiotics that destroy the cell wall

Answer 11

penicillins e.g. amoxicillin

Penicillins work by bursting the cell wall of bacteria. Drugs in the penicillin class work by indirectly bursting bacterial cell walls. They do this by acting directly on peptidoglycans, which play an essential structural role in bacterial cells

Question 12

how does metabolic antagonism work

Answer 12

Interrupting bacterial metabolic pathways that dont exist in humans
Interrupt bacterial metabolic pathways - folic acid

Question 13

why is folic acid needed in bacteria

Answer 13

Folic acid is an essential nutrient necessary for protein and nucleic acid synthesis (DNA and RNA). Folic acid is synthesized by bacteria from the substrate, para-amino-benzoic acid (PABA), and all cells require folic acid for growth.

Question 14

examples of antibiotics that inhibit metabolic pathways

Answer 14

Eg trimethoprim ( competitive ) and sulfadiazine ( abtruct it thus preventing Dna synthesis so inhibit further replication)

Question 15

which enzymes unwinds DNA

Answer 15

DNA gyrase

Question 16

Quinoloes such as ciprofloxacin inhibit what enzyme

Answer 16

DNA gyrase

Question 17

rifamycins such as rifampicin inhibit what enzyme

Answer 17

RNA polymerase

Question 18

what is a pro drug

Answer 18

Drugs can be metabolized by several tissues and organs, such as the kidneys, lungs and intestines, but the main site of metabolism is the liver, which is rich in enzymes. A prodrug is a medication that the body converts into a pharmacologically active drug after it is administered.

Question 19

during inhibition of protein synthesis you can use macrocodes , aminoglycosides and tetracyclines
what do ahminoglycosides do

Answer 19

potent bactericidal antibiotics that act by inhibiting bacterial protein synthesis , thereby binding bacterial 30S and 50S ribosomal subunit, inhibiting the translocation of peptidyl-tRNA from the A site to the P site and also causing misreading of mRNA

e.g. gentamicin

Question 20

what are macrocodes e.g. clarithromycin

Answer 20

treat respiratory and skin and sexually transmitted infections
bind to 50S subunit of the ribosome and inhibit protein synthesis

Question 21

fucntion of tetracycline such as doxycycline

Answer 21

repsriaotry tract infections

Reversibly binds to receptors on the 30S ribosomes subunit of the bacteria preventing attachment of tRNA to RNA complex

Question 22

in the 5th mechanism of bacteria destruction antibiotics can attack the cell membrane - Colistimethate sodium can be used but for what bacteria is this normally reserved for

Answer 22

reserved for gram-negative infections resistant to other antibacterials

Question 23

what is the pneumonic to remember bactericidal (kills bacteria) antibiotics

Answer 23

BANG Q RIP 
beta-lactams 
aminoglycosides 
nitroimidazoles 
glycopeptides 
quinolones 
rifampicin 
polymyxins

Question 24

what is the pneumonic for bacteriostatic( stops bacteria from reproducing) antibiotics

Answer 24

Ms.COLT 
marcolides 
sulfonamides 
chloramphenicol 
oxazolidinones 
lincosamides 
tetracyclines

Question 25

is gentamicin absorbed from the go tract

Answer 25

no

Question 26

mutated/acquired bacteria produce beta-lactamase - what does this do

Answer 26

enzyme that provides multi-resistance to Beta lactame antibiotics such as penicillin

Question 27

what are the 4 mechanisms of acquired antibiotic resistance

Answer 27

1. Spontaneous mutation- when multiplying in DNA changing susceptibility of bacteria to drug
2. Conjugation- bacterial sex uses plasmids taking DNA from bacteria to another
3. Transduction - phage mediated - virus that infects bacteria- taking DNA
4. Transformation - bacterial able to incorporate making DNA into its genome
   These are all hrizontl transformations from one bacteria to another

Question 28

4 main modes of resistance

Answer 28

Altered uptake - reduce mutations entry to bacteria by removing transporter,
promote removal of drug

Drug inactivation- -beta lactamase

Altered target site - altering subunit within ribosomes

Altered metabolic pathway