Brainscape's Knowledge GenomeTM

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


See full index

POM Flashcards (Y1) > Antimicrobial Therapies > Flashcards

Antimicrobial Therapies Flashcards

1
Q

Define antibiotic

A

Antimicrobial agent produced by a microorganism that kills or inhibits other microorganisms.
Target many different bacterial processes and are SELECTIVELY TOXIC

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

What are most antibiotics used today produced by?

A

Soil-dwelling fungi or bacteria

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

Define antimicrobial

A

Chemical that selectively kills or inhibits microbes (bacteria, fungi, viruses)

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

Define bactericidal

A

Kills bacteria

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

Define bacteriostatic

A

Stops bacteria growing

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

Define antiseptic

A

Chemical that kills or inhibits microbes, that is usually used to prevent infection

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

What was the first example of a sulphonamide antibiotic?

A

Prontosil

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

What is prontosil used to treat?

A

Urinary tract infections
Respiratory tract infections
Bacteraemia
Prophylaxis for HIV + individuals

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

What is the mechanism of prontosil?

A

Inhibits dihydropteroate synthase which is critical for synthesis of folate

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

What are the reasons for why antibiotic resistance may lead to increased mortality, morbidity and cost?

A

Increased time to effective therapy
Requirement for additional approaches e.g - surgery
Use of expensive therapy (newer drugs)
Use of more toxic drugs e.g- vancomycin
Use of less effective ‘second choice’ antibiotics

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

Give two examples of aminoglycosides

A

Gentamicin

Streptomycin

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

What is the mechanism of aminoglycosides?

A

Targets 30S ribosomal subunit
Causes damage to cell membrane
Targets protein synthesis and RNA proofreading (aberrant protein production)

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

What do aminoglycosides treat?

A

Severe infections of abdomen and urinary tract
Bacteraemia
Prophylaxis against endocarditis

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

Are aminoglycosides bactericidal or bacteriostatic?

A

Bactericidal

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

What has led to increasing use of aminoglycosides?

A

Resistance to other antibiotics

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

What is the mechanism of rifampicin?

A

Targets RpoB subunit of RNA polymerase (blocks transcription - bactericidal)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What colour does rifampicin make your secretion go?

A

Orange/red - affects compliance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is a frequent issue with Rifampicin?

A

Spontaneous resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the mechanism of vancomycin and is it bactericidal or bacteriostatic?

A

Targets Lipid II component of cell wall biosynthesis, as well as wall cross-linking via D-ala residues
Bactericidal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What has lead to increasing use of vancomycin, despite toxicity?

A

Resistance to other antibiotics, e.g MRSA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the mechanism of linezolid?

A

Inhibits the initiation of protein synthesis by binding to 50S rRNA subunit (bacteriostatic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What spectrum of activity does linezolid have?

A

Gram positive spectrum of activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What limits the dose of daptomycin?

A

Toxicity (has to be delivered intravenously)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the mechanism of daptomycin?

A

Bactericidal - targets bacterial cell membrane

25
Q

What is the spectrum activity of daptomycin?

A

Gram-positive spectrum

26
Q

Give 2 examples of beta-lactams

A

Penicillin

Methicillin

27
Q

What is the mechanism of beta-lactams?

A

Interfere with the synthesis of the peptidoglycan component of the bacterial cell wall (bind to penicillin-binding proteins)
Bactericidal

28
Q

Give 2 processes that are unique to bacterial cells

A

Production of peptidoglycan

Maintenance of LPS layer of gram negative bacteria

29
Q

Give 2 examples of macrolides

A

Erythromycin

Azithromycin (can be used for gonococcal infections)

30
Q

What spectrum of infections do macrolides target?

A

Gram-positive

Some Gram-negative infections

31
Q

Describe the mechanism of macrolides

A

Targets 50S ribosomal subunit preventing amino-acyl transfer

Thus truncation of polypeptides

32
Q

What are quinolones?

A

Synthetic, broad spectrum, bactericidal antibiotics

33
Q

What do quinolones target?

A 
DNA gyrase (Gram -)
Topoisomerase IV (Gram +)
34
Q

What are quinolones used to treat?

A

Lower respiratory tract infection, blood infections, UTIs (e.g gonococcal) and skin infections

35
Q

What is meant by resistance?

A

If a bacterium can grow at or above the breakpoint concentration (minimal inhibitory concentration of antibiotic)

36
Q

Why might there be more of a resistance to penicillin in hospitals than the community?

A

Routine use of penicillin in hospitals provides a selection pressure
For the acquisition and maintenance of resistance genes

37
Q

What are the 4 distinct mechanisms by which antibiotic resistance can occur?

A

Altered target site
Inactivation of antibiotic
Altered mechanism (bypass processes inhibited by AB)
Decreased drug accumulation

38
Q

Give 2 examples in which a target site can be altered

A

MRSA encodes alternative PBP with low affinity for beta lactams

Acquisition of erm gene by streptococcus pneumoniae encodes an enzyme that methylates AB target site in 50S ribosomal subunit

39
Q

How does inactivation of antibiotic occur?

A

Enzymatic degradation or alteration, rending antibiotic ineffective.

E.g beta-lactamases (bla) and chloramphenicol acetyl-transferase (cat)

40
Q

What is one of the greatest threats to antibiotic use at the moment?

A

Bacteria that encode broad-spectrum beta-lactamases

Such as ESBL and NDM-1 which can degrade a wide range of beta-lactams

41
Q

How does the altered metabolism pathway occur within antibiotic resistance?

A

Increased production of enzyme substrate can out-compete antibiotic for target site, e.g increased PABA production - resistance to sulphonamides
Bacteria can switch to other metabolic pathways, reducing requirement for PABA

42
Q

How does decreased drug accumulation occur?

A

Reduced penetration of AB into bacterial cell
Or increased efflux pumps to keep AB out of cell
Makes it so that AB doesn’t reach concentration in cell to be effective

43
Q

What gram negative bacteria is associated with cystic fibrosis, burn wound infections and survives on abiotic surfaces?

A

Pseudomonas aeruginosa

44
Q

What gram negative bacteria is associated with GI infection, neonatal meningitis, septicaemia and UTI?

A

E.coli

45
Q

What gram negative bacteria is associated with GI infection and typhoid fever?

A

Salmonella spp.

46
Q

What gram negative bacteria is associated with opportunistic infections, wounds, UTI, pneumonia and survives on abiotic surfaces?

A

Acinetobacter baumannii

47
Q

What gram positive bacteria is associated with wound and skin infections, pneumonia, scepticaemia and infective endocarditis?

A

Staphylococcus aureus

48
Q

What gram positive bacteria is associated with pseudomembranous colitis and antibiotic-associated diarrhoea?

A

Clostridium difficile

49
Q

What gram positive bacteria is associated with UTI, bacteraemia and infective endocarditis?

A

Enterococcus spp

50
Q

What are the 3 sources of antibiotic resistant genes and how do they work?

A

Plasmids - extra-chromosomal circular DNA, often carry multiple AB resistant genes and selection for one maintains resistance for all
Transposons - integrate into chromosomal DNA and allow transfer of genes from plasmid to chromosome and vice versa
Naked DNA - DNA from dead bacteria released into the environment

51
Q

Describe the 3 ways that bacteria can spread their AB resistant genes.

A

Transformation - uptake of extracellular DNA
Transduction (phage-mediated) - viruses infect bacteria and take up some of their DNA and then go on to infect other bacteria, passing on the DNA
Conjugation - bacterial sex to share plasmids between them

52
Q

Give some of the non-genetic mechanisms of resistance/treatment failure.

A

Biofilm - matrix encased communities of bacteria that are highly drug tolerant will minimise penetrative effect of antibiotics
Intracellular location - harder for antibiotics to get to bacteria
Slow growth - hard for antibiotics to inhibit replication processes if they do not occur as much
Spores - resistant to heat, antibiotics, antiseptics; spore coat is impermeable to antibiotics, preventing access to target organelles
Persisters - dormant bacteria that are not carrying out the processes that antibiotics inhibit

53
Q

What are three solutions to reducing antibiotic resistance?

A

Phage antibiotic combination therapy
Modifications of existing antibiotics (prevent cleavage)
Combination of inhibitor and antibiotic

54
Q

In what sectors are antibiotics used more?

A

Critical care

Wards

55
Q

What are some of the risk factors for HAI?

A 
High number of ill people
Crowded wards
Presence of pathogens
Broken skin - surgical wound/IV catheter
Indwelling devices - intubation
AB therapy - may suppress normal flora
Transmission by staff - contact with multiple patients
56
Q

How might AB therapy impair commensal flora?

A

AB therapy removes commensal organisms
Pathogen has no competition leading to overgrowth
Pathogen produces toxins and damages host-symptomatic infection
Spreads to other patients

57
Q

Give some of the methods we might use to address resistance

A

Prescribing strategies - tighter controls, temporary withdrawal of certain classes and restrictions of ABs for certain serious infections
Reduced use of broad spectrum antibiotics
Quicker identification of infections caused by resistant strains
Combination therapies
Clinicians should have knowledge of local strains and resistance patterns

58
Q

What 3 broad classes of conditions are caused by fungi?

A

Allergy - allergic reactions to fungal products, e.g ABPA
Mycotoxicoses - ingestion of fungi and their toxic products, e.g aflatoxin
Mycoses - superficial, subcutaneous or systemic colonisation, invasion and destruction of human tissue.

59
Q

What do fungi cell membranes contain instead of cholesterol?

A

Ergosterol

Also have a cell wall

POM Flashcards (Y1) (28 decks)

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