Antibiotic Therapies

Question 1

What are bacteriostatic antibiotics

Answer 1

inhibit the growth of bacteria

Question 2

what are bacteriocidal antibiotics

Answer 2

kill bacteria

Question 3

What gives an antibiotic a broad spectrum

Answer 3

act against many gram negative and gram positive bacteria

Question 4

What are the qualities of an ideal antibiotic

Answer 4

selective toxicity
long half-life (no constant administering)
appropriate tissue distribution

Question 5

what is selective toxicity

Answer 5

antibiotic targets the bacteria and not the host

Question 6

is 100% of an oral antibiotic absorbed

Answer 6

no

Question 7

how are oral antibiotics excreted

Answer 7

urine
liver/ biliary tract into faeces

Question 8

What processes are targeted by antibiotics

Answer 8

peptidoglycan synthesis
protein synthesis
nucleic acid synthesis

Question 9

What are common cell wall anti-microbials

Answer 9

penicillins
cephalosporins
glycopeptides

Question 10

which common cell wall antimicrobials are beta-lactam sensitive

Answer 10

penicillin
cephalosporins

Question 11

what are the targets of B-lactams

Answer 11

penicillin binding proteins (PBP)

Question 12

How do B-lactam antimicrobials work

Answer 12

antimicrobials contain B-lactam ring
recognised by cell wall synthesising enzyme
synthesis halted

Question 13

What dipeptide is mistook for B-lactam by enzyme

Answer 13

D-alanine D-alanine terminal

Question 14

How are the penicillins excreted

Answer 14

rapidly via kidneys

Question 15

What are the limitations of the penicillins

Answer 15

patients can be hypersensitive (allergic)
rapid excretion
resistance

Question 16

How have microbes developed a penicillin resistance

Answer 16

clinical overuse
penicillin was exposed to many microbes
resistant strains naturally selected for

Question 17

Which type of organism is flucloxacillin used on

Answer 17

gram positive organisms

Question 18

Which type of penicillin is used on gram negative and gram positive microbes

Answer 18

amoxicillin

Question 19

Which type of penicillin is used on gram negative organisms only

Answer 19

temocillin

Question 20

Why is co-amoxiclav used

Answer 20

contains clavulanic acid which inhibits B-lactamases

Question 21

Why are the benefits of amoxicillin

Answer 21

well absorbed orally
good tissue distribution

Question 22

What are B-lactamases

Answer 22

microbial enzymes that destroy the B-lactam ring

Question 23

What penicillin is prescribed for staphylococci and streptococci only

Answer 23

flucloxacillin

Question 24

What are the properties of cephalosporins

Answer 24

long half life
few side effects
more resistance to B-lactamases
broad range

Question 25

How are cephalosporins excreted

Answer 25

kidneys/urine

Question 26

what is the downside of an antibiotic with a broad range

Answer 26

can have an impact on the host (flora)

Question 27

How do glycopeptides work

Answer 27

binds to end of peptide side chains inhibits peptidoglycan synthesis

Question 28

How are glycopeptides excreted

Answer 28

kidneys/urine

Question 29

why do glycopeptides only work on gram positive organisms

Answer 29

outer membrane in gram negative organisms stops use of glycopeptides

Question 30

How do antibiotics target metabolic pathways

Answer 30

microbes contain pathways unique to them

Question 31

How do protein synthesis inhibitors target prokaryotes

Answer 31

prokaryotic ribosomes differ to eukaryotic ribosomes

Question 32

How do protein synthesis inhibitors work

Answer 32

attach to bacterial ribosomes blocking steps in protein synthesis

Question 33

what type of protein synthesis inhibitor has transient ribosome binding

Answer 33

bacteriostatic - protein synthesis resumed once antibiotic is removed

Question 34

what type of protein synthesis inhibit has permanent ribosome binding

Answer 34

bacteriocidal

Question 35

What are the 3 main classes of protein synthesis inhibitors prescribed

Answer 35

aminoglycosides tetracyclines macroslides

Question 36

What is a common aminoglycoside prescribed

Answer 36

gentamicin

Question 37

What are the properties of gentamicin

Answer 37

given IV (not gut absorbed) mainly used for gm -ve aerobic

Question 38

What is the risk associated with gentamicin

Answer 38

causes damage to kidneys

Question 39

what are the properties of tetracyclines

Answer 39

stops peptide chain elongation broad spectrum

Question 40

what are the risks associated with tetracyclines

Answer 40

increasing resistance destruction to normal gut flora

Question 41

what happens if gut flora is damaged

Answer 41

results in increasing risk to secondary infections to C.diff

Question 42

How do macro slides inhibit protein synthesis

Answer 42

bind to 50s subunit block translocation/release of peptide

Question 43

what antibiotics target nucleic acids

Answer 43

fluoroquinolones metronidazole

Question 44

How do quinolones kill bacteria

Answer 44

bind to DNA subunit and prevent supercoiling - new dna cannot be synthesised

Question 45

What is metronidazole prescribed for

Answer 45

anaerobes Protozoa

Question 46

What intermediate metabolism can be blocked by antibiotics

Answer 46

folic acid synthesis

Question 47

why should bactericidal and bacteriostatic antibiotics never be combined

Answer 47

cancel each other out block protein synthesis - need lytic enzymes

Question 48

why are some antibiotics given in combination

Answer 48

cover broad range of possible infections prevent development of resistance

Question 49

which 4 antibiotics increase the risk of a C.diff infection

Answer 49

Cephalosporins co-amoxiclav ciprofloxacin clindamycin

Question 50

What type of bacteria are tetracyclines used against

Answer 50

intracellular