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Immunology and infection > Antimicrobial Therapies > Flashcards

Antimicrobial Therapies Flashcards

1
Q

What is an antibiotic

A

Antimicrobial agent produced by a microorganism that kills or inhibits other microorganisms

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2
Q

What does bacteriocidal bacteria do

A

Kills bacteria

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3
Q

What does bacteriostatic bacteria do

A

Stops bacteria from growing

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4
Q

Why is antibiotic resistance bad

A 
Requirement for additional surgeries
More expensive therapy
More toxic drugs
Less effective second choice drug
Increased time to effective therapy
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5
Q

What type of antibiotic is aminoglycosides

A

Bactericidal

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6
Q

What do aminoglycosides target

A 
Protein synthesis (30s ribosomaml subunit), RNA proofreading and causes damage to cell membrane
Toxicity is high - hearing loss
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7
Q

What type of antibiotic is rifampicin

A

Bactericidal

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8
Q

What does rifampicin target

A

RpoB subunit of RNA polymerase
Secretions go orange/red
Spontaneous resistance is frequent

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9
Q

What type of antibiotic is vancomycin

A

Bactericidal

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10
Q

What does vancomycin target

A

Lipid II component of cell wall biosynthesis as well as wall crosslinking via D-ala residues
Used against MRSA

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11
Q

What type of antibiotic is linezolid

A

Bacteriostatic

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12
Q

What does linezolid do

A

Inhibits the initiation of protein synthesis by binding to 50s rRNA subunit
Does not affect gram negative bacteria due to LPS in the membrane

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13
Q

What type of antibiotic is daptomycin

A

Bactericidal

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14
Q

What does daptomycin target

A

Bacterial cell membrane
Cannot target LPS in gram negative
Toxicity limits dose - only inpatient settings

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15
Q

What type of antibiotic is beta-lactams

A

Bacteriostatic

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16
Q

What do beta-lactams target

A

Interfere with synthesis of peptidoglycan compoment of the bacterial cell wall

17
Q

What is selective toxicity

A

Target things in bacteria which aren’t present in humans

e.g. LPS layer and peptidoglycan layer

18
Q

What do macrolides target

A

Gram positive but sometimes gram negative

Targets 50s ribosomal subunit preventing amino-acyl transfer and truncation of polypetides

19
Q

What do quinolones target

A

DNA gyrase in gram neg
Topoisomerase 4 in gram pos
DNA damage and death of organism

20
Q

What type of antibiotic is quinolones

A

Bactericidal

21
Q

What is the breakpoint of antibiotics

A

Clinically-achieveable concentration of given antibiotic in host tissues

22
Q

What is the minimal inhibitory concentration

A

Lowest concentration of drug to inhibit growth

23
Q

What are the 4 mechanisms of antibiotic resistance

A

Altered target site
Inactivation of antibiotic
Altered metabolism
Decreased drug accumulation

24
Q

What is the action of altered target sites

A

Mutation in gene encoding target site
MRSA - alternative penicillin binding protein with low affinity to beta-lactams
Streptococcus pneumoniae - acquires genes which encodes enzyme that methylates target site

25
Q

What is the action of inactivation of antibiotic

A

Beta-lactamase enzyme which inhibits the beta lactame ring
Enzymatic degradation of alteration of antibiotic
ESBL and NDM-1 - broad-spectrum beta-lactamase

26
Q

What is the action of altered metabolism

A

Enzymes substrates are produced that outcompete target site

Bacteria switch to other metabolic pathways

27
Q

What is the action of decreased drug accumulation

A

Decrease penetration of antibiotic

Increase efflux of AB out of the cell

28
Q

What are some exogenous causes of antibiotic resistance

A

Plasmids - extra-chromosomal circular DNA
Transposons - DNA that jumps, integrate into chromosomal DNA
Naked DNA - DNA from dead bacteria

29
Q

How to bacteria take up DNA

A

Transformation - take up DNA from environment
Transduction - Virus infect bacteria, take up DNA and then infect other bacteria
Conjugation - bacterial sex to share plasmids

30
Q

Non-genetic mechanisms for treatment failure

A 
Matrix incased communities of bacteria
Intracellular location
Slow growth - doesn't replicate fast
Spores - antibiotic, antiseptic, heat resistant
Persisters - dormant organisms
31
Q

Other reasons for treatment failure

A

Inappropriate choice of organisms
Poor penetration of target site
Inappropriate dose
Inappropriate administration

32
Q

What are some hospital acquired infections

A 
Methicillin-resistant S. aureus
Vancomycin-insensitive S aurues
Clostridium difficle
Vancomycin-resistant enterococci
E coli
P aeruginosa
Acineterbacter baumannii
Stenotrophomonas maltophilia
33
Q

Risk factors for HAI

A 
High number of ill people
Crowded wards
Presence of pathogens
Broken skin
Indwelling devices
Transmission by staff
34
Q

How do we address resistance

A 
Tighter control
Temporary withdrawal of antibiotics
Restriction for serious infections
Reduce use of broad-spectrum antibiotics
Quicker identification of infections
Combination therapy
35
Q

How can beta lactams be modified to be more effective

A

Methicillin - prevent cleavage of beta-lactams

Augmentin - beta-lactamase inhibitor

36
Q

How can we prevent the gut flora biome from being destroyed

A

Use of non-pathogenic competitor strains

Immunology and infection (14 decks)

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