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Medicine Term One > Antimicrobial chemotherapy: mechanisms of bacteria and resistance to bacteria > Flashcards

Antimicrobial chemotherapy: mechanisms of bacteria and resistance to bacteria Flashcards

1
Q

Name two healthcare acquired infections

A

Clostridium difficle

MRSA

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2
Q

What are antibiotics active against

A

bacteria

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3
Q

Bactericidal

Bacteriostatic

A

An antimicrobial that kills bacteria

An antimicrobial that inhibits growth of bacteria

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4
Q

When is an organism considered sensitive

A

it is inhibited or killed by levels of the antimicrobial that are available at the site of an infection

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5
Q

When is an organism considered resistant

A

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

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6
Q

What are the three routes of administration for antibiotics

A

Topical - skin surface
Systemic - Orally/Internally
Parenteral - IV or intramuscularly

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7
Q

What are the three metabolic areas that antibiotics inhibit to kill bacteria

A

Cell wall
Nucleic acid synthesis
Protein synthesis

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8
Q

Why are human cells not affected by antibiotics

A

as human cells do not have a cell wall

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9
Q

What antibiotics inhibit cell wall synthesis

A

Penicillins
Cephalosporins
Glycopeptides

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10
Q

What are Penicillins and Cephalosporins classed as and who do they inhibit call wall growth

A

Beta- Lactams

Disrupt peptidoglycan synthesis by inhibiting enzymes responsible for cross linking the carbohydrate chains

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11
Q

what happens to a bacteria when the cell wall has been disrupted

A

Organism finally killed by autolytic enzymes

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12
Q

What is the structural component of the bacterial cell wall and the enzymes known as

A

Penicillin binding proteins

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13
Q

What was the original B- Lactam discovered and why are gram negative organisms resistant

A

Benzyl Penicillin

Impermeability of gram negative cell wall

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14
Q

Whats a MIC (minimal inhibitory concentration)

A

Min conc of antimicrobial needed to inhibit visible growth of a given organism

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15
Q

What is a MBC (minimal bactericidal concentration)

A

Min conc of the antimicrobial needed to kill a given organism

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16
Q

What are two glycopeptide antibodies

A

Vancomycin and Teicoplanin

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17
Q

How do glycopeptides work

A

Inhibit peptidoglycan precursor acting prior to B-Lactam

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18
Q

What Bacteria can glycopetides not penetrate

A

Gram negative, therefore only act on Gram positive

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19
Q

Where are glycopeptides not absorbed and how are they administrated

A

GI tract

Usually Parentally

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20
Q

What is a common problem with vancomycin

A

toxicity

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21
Q

What antimicrobials inhibit protein synthesis

A

Aminoglycosides
Macrolides and Tetracyclines
Oxazoldinones
Cyclic Lipopeptide

22
Q

What is a common aminoglycoside and and what infections do they provide a useful treatment

A

Gentamicin

Gram negative coliform infections including pseudomonas

23
Q

Why does Gentamicin dosage have to be monitored

A

Because of it toxicity

24
Q

What are Macrolides and Tetracyclines are used as alternatives to penicillin to treat

A

Gram positive infections

25
Q

What are examples of Macrolides

A

erthromysin

clarithromysin

26
Q

What is an example of a Oxazolidinones, and what is it active against

A

Linezolid

Good activity against MRSA and held in reserve for serious infections

27
Q

What is an example of a cyclic lipopeptide and what is it active against

A

Daptomycin
Active against Gram positives and MRSA
Used in serious infections

28
Q

How do antibiotics inhibit nucleic acid synthesis

A

By interrupting the supply of precursors for DNA synthesis

29
Q

What antimicrobials inhibit nucleic acid synthesis

A

Trimethoprim and Sulphamethoxazole

Fluoroquinolones

30
Q

What is Co- Trimoxazole

A

the combined drug of Trimethoprim and Sulphamethoxazole

31
Q

What does Co- Trimoxazole commonly used to treat

A

Urine infections

32
Q

What is an example of a Fluoroquinolones antibiotic and why is it good and more active against

A

ciproflaxin
Inhibits DNA synthesis more directly
Effective against gram negative organisms including pseudomonas

33
Q

Who can ciproflaxin not be used on and why

A

On children can interfere with cartilage growth

34
Q

In some cases all strains of a given species are resistant to antibiotic because

A

Inability of drug to penetrate the bacterial cell wall

35
Q

What is acquired resistance

A

resistance may be present in some strains of species but not in others

36
Q

What are the two ways resistance can be acquired

A

A spontaneous mutation (target has changed)

Genes that code fro resistance transferred via plasmid or transposons

37
Q

How does the widespread of antibiotics cause selective pressure

A

encourages new resistant organisms to outgrow sensitive strains

38
Q

what are b-lactamases

A

Bacterial enzymes that cleave the b-lactam ring of antibiotics = inactive

39
Q

Example of a strain producing b-lactamase and what its resistant to

A

staphylococcus - staph aureas MRSA

resistant to - benzyslpenacillin

40
Q

What is the two ways is B- lactase combats b-lactamase and examples

A

By adding a second component B-lactamase inhibitor
eg co-amoxiclav
Modify antibiotic side chain, (make antibiotic resistant)
eg Flucloxacillin

41
Q

What is a modified from of penicillin

A

Flucloxacillin

42
Q

What is the name of gram negative organisms resistant to carbapems

A

Carbapenemas producing enterobacteriaceae (CPE)

43
Q

CPE organims is worrying because

A

Carbapems is a wide range of antibiotics

and this type of resistance is the same for a multiple form antibiotics

44
Q

What is the two ways micro-organisms develop resistance to B-lactams

A

B-lactamase production to inactivate antibiotic

Alteration of penicillin biding proteins

45
Q

When does the addition of B- lactamase inhibitor make no difference to antibiotic

A

when bacterias penicilian binding sites are altered

46
Q

What is an example of bacteria with altered penicillin binding protein

A

MRSA methicin resistant staph aureas

47
Q

What is MRSA resistant to

A

all penicillins and cephalosporins

48
Q

What are extended spectrum B-lactamases resistant produced by and what are they resistant to

A

produced by some gram negative organisms

resistant to all B-lactam agents

49
Q

What effect do Vancomycin resistant enterococci gram positive bacteria have on the antibiotic

A

peptidoglycan precursor to which the antibiotic vancomysin normally binds on a gram positive bacteria have altered = resistant

50
Q

What antibiotic inhibits purine synthesis

A

trimethoprim

Medicine Term One (59 decks)

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