Antimicrobial chemotherapy: mechanisms of bacteria and resistance to bacteria Flashcards Preview

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Flashcards in Antimicrobial chemotherapy: mechanisms of bacteria and resistance to bacteria Deck (50):
1

Name two healthcare acquired infections

Clostridium difficle
MRSA

2

What are antibiotics active against

bacteria

3

Bactericidal
Bacteriostatic

An antimicrobial that kills bacteria
An antimicrobial that inhibits growth of bacteria

4

When is an organism considered sensitive

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

5

When is an organism considered resistant

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

6

What are the three routes of administration for antibiotics

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

7

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

Cell wall
Nucleic acid synthesis
Protein synthesis

8

Why are human cells not affected by antibiotics

as human cells do not have a cell wall

9

What antibiotics inhibit cell wall synthesis

Penicillins
Cephalosporins
Glycopeptides


10

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

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

11

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

Organism finally killed by autolytic enzymes

12

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

Penicillin binding proteins

13

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

Benzyl Penicillin
Impermeability of gram negative cell wall

14

Whats a MIC (minimal inhibitory concentration)

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

15

What is a MBC (minimal bactericidal concentration)

Min conc of the antimicrobial needed to kill a given organism

16

What are two glycopeptide antibodies

Vancomycin and Teicoplanin

17

How do glycopeptides work

Inhibit peptidoglycan precursor acting prior to B-Lactam

18

What Bacteria can glycopetides not penetrate

Gram negative, therefore only act on Gram positive

19

Where are glycopeptides not absorbed and how are they administrated

GI tract
Usually Parentally

20

What is a common problem with vancomycin

toxicity

21

What antimicrobials inhibit protein synthesis

Aminoglycosides
Macrolides and Tetracyclines
Oxazoldinones
Cyclic Lipopeptide

22

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

Gentamicin
Gram negative coliform infections including pseudomonas

23

Why does Gentamicin dosage have to be monitored

Because of it toxicity

24

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

Gram positive infections

25

What are examples of Macrolides

erthromysin
clarithromysin

26

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

Linezolid
Good activity against MRSA and held in reserve for serious infections

27

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

Daptomycin
Active against Gram positives and MRSA
Used in serious infections

28

How do antibiotics inhibit nucleic acid synthesis

By interrupting the supply of precursors for DNA synthesis

29

What antimicrobials inhibit nucleic acid synthesis

Trimethoprim and Sulphamethoxazole
Fluoroquinolones

30

What is Co- Trimoxazole

the combined drug of Trimethoprim and Sulphamethoxazole

31

What does Co- Trimoxazole commonly used to treat

Urine infections

32

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

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

33

Who can ciproflaxin not be used on and why

On children can interfere with cartilage growth

34

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

Inability of drug to penetrate the bacterial cell wall

35

What is acquired resistance

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

36

What are the two ways resistance can be acquired

A spontaneous mutation (target has changed)
Genes that code fro resistance transferred via plasmid or transposons

37

How does the widespread of antibiotics cause selective pressure

encourages new resistant organisms to outgrow sensitive strains

38

what are b-lactamases

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

39

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

staphylococcus - staph aureas MRSA
resistant to - benzyslpenacillin

40

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

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

41

What is a modified from of penicillin

Flucloxacillin

42

What is the name of gram negative organisms resistant to carbapems

Carbapenemas producing enterobacteriaceae (CPE)

43

CPE organims is worrying because

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

44

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

B-lactamase production to inactivate antibiotic
Alteration of penicillin biding proteins

45

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

when bacterias penicilian binding sites are altered

46

What is an example of bacteria with altered penicillin binding protein

MRSA methicin resistant staph aureas

47

What is MRSA resistant to

all penicillins and cephalosporins

48

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

produced by some gram negative organisms
resistant to all B-lactam agents

49

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

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

50

What antibiotic inhibits purine synthesis

trimethoprim

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