Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

SA infections > S4) Antimicrobials and Resistance ❌❌❌❌❌ > Flashcards

S4) Antimicrobials and Resistance ❌❌❌❌❌ Flashcards

1
Q

Identify 4 different ways in which antibacterial agents can be classified

A
  • Bactericidal / bacteriostatic (kill/disable)
  • Broad / narrow (spectrum)
  • Mechanism of action (target site)
  • Antibacterial class (chemical structure)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 6 ideal features for antimicrobial agents?

A
  • Selectively toxic
  • Few adverse effects
  • Reach site of infection
  • Oral/IV formulation
  • Long half-life (infrequent dosing)
  • No interference with other drugs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Identify the different classes of antimicrobials based on their different mechanisms of action

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

Identify and describe the different types of resistance

A
  • Intrinsic: no target or access for the drug (usually permanent)
  • Acquired: acquires new genetic material or mutates (usually permanent)
  • Adaptive: organism responds to a stress (usually reversible)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Identify the different mechanisms of resistance and provide examples

A
  • Drug-inactivating enzymes e.g. b-lactamases, aminoglycoside enzymes
  • Altered target (lowered affinity for antibacterial) e.g. resistance to macrolides & trimethoprim
  • Altered uptake

I. ↓permeability e.g. b-lactams

II. ↑efflux e.g. tetracyclines

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

Identify the four Beta-lactam subgroups

A
  • Penicllins
  • Cephalosporins
  • Carbapenems
  • Monobactams
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Provide some examples of penicillins in the Beta-lactam sub-group and describe their use

A
  • Penicillin – active against strep
  • Amoxicillin – active against staph & strep (+ ↑Gneg)
  • Flucloxacillin – active against staph & strep
  • Β-lactamase inhibitor combinations e.g. co-amoxiclav – acitive against staph & strep and anaerobes (↑Gneg)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the use of cephalosporins in the Beta-lactam sub-group and provide some examples

A
  • ↑Gneg and ↓Gpos activity
  • ↑broad-spectrum (no anaerobes)
  • E.g. ceftriaxone has good activity in the CSF IV but associated with C. difficile*
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the use of carbapenems in the Beta-lactam subgroup and provide some examples

A
  • Broad spectrum (+ anaerobes)
  • Active against most Gnegs
  • Safe in penicillin allergy
  • E.g. meropenem and imipenem*
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Provide two examples of glycopeptides

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

Describe the use of vancomycin in the Glycopeptide subgroup

A
  • Active against most Gpos
  • Rare resistance in staphs
  • Oral for C. difficile only (otherwise IV)
  • stops cell wall linkage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the use of teicoplanin in the Glycopeptide subgroup

A
  • Similar activity to vancomycin
  • Easier to administer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Provide two examples of tetracyclines

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

Describe the use of doxycyline & tetracycline in the tetracyline subgroup

A
  • Oral administration
  • Broad-spectrum
  • Gpos (use in pencillin allergy)
  • Active in atypical pathogens in pneumonia & against chlamydia
  • Shouldn’t be given to children < 12 years
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Provide an example of an aminoglycoside

A

Gentamicin

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

Describe the use of gentamicin in the aminoglycoside subgroup

A
  • Activity against Gnegs
  • Good activity in the blood/urine
  • Generally reserved for severe Gram neg sepsis
17
Q

Provide two examples of macrolides

A
  • Erythromycin
  • Clarithromycin
18
Q

Describe the use of erythromycin and clarithromycin in the macrolide subgroup

A
  • Used for mild Gpos infections (alternative to penicillin)
  • Active against atypical respiratory pathogens
19
Q

Provide an example of a quinolone

A

Ciprofloxacin

20
Q

Describe the use of quinolones

A

- Inhibit DNA gyrase

  • Very active against Gnegs
  • Active against atypical pathogens
  • Increasing resistance
  • Risk of C. difficile
21
Q

Describe the use of trimethoprim

A
  • Inhibits folic acid synthesis
  • Used alone in the UK for UTI
22
Q

Identify two subgroups of antifungal agents

A
  • Azoles
  • Polyenes
23
Q

Describe the use of azoles and provide some examples

A

Inhibit cell membrane synthesis:

  • Flucanazole used to treat candida
  • Posaconazole also active against aspergillus
24
Q

Describe the use of polyenes and provide some examples

A

Inhibit cell membrane function:

  • Nystatin for topical treatment of candida
  • Amphotericin for IV treatment of systemic fungal infections
25
Q

Provide some examples of antiviral agents

A
  • Aciclovir
  • Oseltamivir
  • Specialist agents for HIV, HBV, HCV, CMV
26
Q

Describe the use of aciclovir

A
  • Inhibits viral DNA polymerase (when phosphorylated)
  • Used to treat HSV and varicella zoster virus
27
Q

Describe the use of oseltamivir

A
  • Inhibits viral neuraminidase
  • Used to treat influenza A & B
28
Q

Describe the use of metronidazole (antibacterial and antiprotozoal agent)

A
  • Active against anaerobic bacteria
  • Also active against protozoa e.g. amoebae, giardia (diarrhoea), trichomonas (vaginitis)
29
Q

What are the consequences of antibacterial resistance?

A
  • Treatment failure
  • Prophylaxis failure
  • Economic costs
30
Q

Identify and describe the different definitions of antimicrobial resistance

A
  • MDR (multi-drug resistant): non-susceptibility to at least one agent in three or more antimicrobial categories
  • XDR (extensively drug resistant): non-susceptibility to at least one agent in all but two or fewer antimicrobial categories
  • PDR (pan-drug resistant): non-susceptibility to all agents in all antimicrobial categories
31
Q

how to choose an antibiotic

A
  • is it active against target organism
  • does it reach site of infection (can it pass the blood brain barrier)
  • is it available in the right formulation (IV/oral) - eg if they have had bowel surgery then it cant absorb
  • whats the half life
  • does it interact with other drugs
  • is there toxicity issues
  • does it require therapeutic drug monitoring
32
Q

measuring antibiotic activity

A

disc testing - put different antibiotics and then see the spread of bacteria

quick and inexpensive

MIC - but different concentrations of antibiotics and see what conc the bacteria stops growing. sterile control ( only antibiotic and one with only bacteria to see if its growing) MIC is the conc at which it stops growing

MIC - E test - strip with different concs of antibiotcs and then place it with bacteria and see dostance it grows

33
Q

intrinsic antibiotic resistance

A

bacterial species naturally resistant to a certain antibiotic family withiut the need for further mutations of genes

permenant

34
Q

acquired antibiotic resistance

A

when a particular organism obtains the ability to resist the activity of a particular antimicrobial agent to which it was previously susceptible

the change is due to gene mutation or gene transfer via plasmid

mechanisms

enzyme modification // destruction of antibiotics

enzyme alteration of antibiotic

35
Q

adaptive antibiotic resistance

A

responds from stress

36
Q

gram negative bacterial replication

A

punjugation

single strand of plasmid from donor bacteria transfers to new bacteria via the pillus

both manufacture a second strand = 2 complete plasmids

DANGEROUS as they dont have to be the same species

SA infections (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions