Anti-microbial Chemotherapy Flashcards

1
Q

What is MIC

A

the minimal inhibitory concentration is defined as the minimum concentration of antimicrobial needed to inhibit visible growth of a given organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is MBC

A

the minimal bactericidal concentration is defined as the minimum concentration of antimicrobial of the antimicrobial needed to kill the given organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does it mean for an organism to be sensitive

A

If it is inhibited or killed by levels of the antimicrobial that are available at the site of action

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what does it mean for an organism to be resistant

A

If it is not killed or inhibited by levels of the antimicrobial that are available at the site of the infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a Bactericidal

A

an antimicrobial that kills bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a Bacteriostatic

A

An antimicrobial that inhibits growth of bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The mechanism of action of antibacterial drugs

A

inhibition of cell wall synthesis

inhibition of protein synthesis

Inhibition of nucleic acid synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Inhibition of cell wall synthesis

A

Penicillins and cephalosporins - contail B-lactams, inhibit enzymes responsible for cross-linking carbohydrates to form peptidoglycan chains

Glycopeptides - vancomycin and teicoplanin, act on stage prior to when B-lactams act, inhibiting the production os peptidogylcan precursor, only act on gram +ve bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Inhibition of Protein synthesis

A

Aminoglycosudes- gentamicin, mainly used to treat Gram -ve infections

macrolides and tetracyclines - erythromycine, clarithromycin, used in gram +ve infections, mainly used to treat haemophilus influenza

Oxazolidinones - linezolid, used against MRSA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

inhibition of nucleic acid synthesis

A

trimethoprim and sulphamethoxazole - inhibit different steps in purine synthesis, ised in combined form, co-trimoxazole for chest infections, trimwethoprim for UTI’s

Fluoroquinolones - ciprofloxacin, inhibit DNA synthesis more directly, effective against gram -ve infection, cannot be used in children due to danger of cartilage growth interference

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

the mechanism of action for antifungal drugs

A

polyenes, azoles, allylamines, echinocandins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

action of polyenes

A

bind to erosterol and make cell wall more permeable

amphoyericin B is used to treat serious fungal and yeast infections but is toxic

nystatin is used topically or in oral suspension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

action of azoles

A

inhibit ergosterol synthesis

fluconazole is used to treat yeast infections, but not all are sensitive

voriconazole and itraconazole used to treat aspergilliosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

action of allylamines

A

suprerss ergosterol synthesis but at a differet stage than azoles

terbinafine is the only one in use

mainly used against deratophytes and clinical use is restricted to infection of skin and nail

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

action of echinocandins

A

inhibit the production of glucan ploysaccharide

casofungin is used in serious candida and aspergillus infection

it is a safe, IV only drug

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

clinically significant resistant mechanisms to combat B-lactam activity

A

some organisms (staph. aureus) produse B-lactamase enxymes which can break down penicillins and cephalosporins

flucloxallin is lactamase resistant and so can still treat these bacteria

some organisms (MRSA) have altered binding sites to which the drugs cannot adhere rendering MRSA immune to all penicillins and cephalosporins

some gram -ve bacteria produce extended spectrum B-lactamase which renders them resistant to all B-lactams