Antimicrobial chemotherapy: mechanisms of bacteria and resistance to bacteria

Question 1

Name two healthcare acquired infections

Answer 1

Clostridium difficle

MRSA

Question 2

What are antibiotics active against

Answer 2

bacteria

Question 3

Bactericidal

Bacteriostatic

Answer 3

An antimicrobial that kills bacteria

An antimicrobial that inhibits growth of bacteria

Question 4

When is an organism considered sensitive

Answer 4

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

Question 5

When is an organism considered resistant

Answer 5

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

Question 6

What are the three routes of administration for antibiotics

Answer 6

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

Question 7

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

Answer 7

Cell wall
Nucleic acid synthesis
Protein synthesis

Question 8

Why are human cells not affected by antibiotics

Answer 8

as human cells do not have a cell wall

Question 9

What antibiotics inhibit cell wall synthesis

Answer 9

Penicillins
Cephalosporins
Glycopeptides

Question 10

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

Answer 10

Beta- Lactams

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

Question 11

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

Answer 11

Organism finally killed by autolytic enzymes

Question 12

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

Answer 12

Penicillin binding proteins

Question 13

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

Answer 13

Benzyl Penicillin

Impermeability of gram negative cell wall

Question 14

Whats a MIC (minimal inhibitory concentration)

Answer 14

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

Question 15

What is a MBC (minimal bactericidal concentration)

Answer 15

Min conc of the antimicrobial needed to kill a given organism

Question 16

What are two glycopeptide antibodies

Answer 16

Vancomycin and Teicoplanin

Question 17

How do glycopeptides work

Answer 17

Inhibit peptidoglycan precursor acting prior to B-Lactam

Question 18

What Bacteria can glycopetides not penetrate

Answer 18

Gram negative, therefore only act on Gram positive

Question 19

Where are glycopeptides not absorbed and how are they administrated

Answer 19

GI tract

Usually Parentally

Question 20

What is a common problem with vancomycin

Answer 20

toxicity

Question 21

What antimicrobials inhibit protein synthesis

Answer 21

Aminoglycosides
Macrolides and Tetracyclines
Oxazoldinones
Cyclic Lipopeptide

Question 22

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

Answer 22

Gentamicin

Gram negative coliform infections including pseudomonas

Question 23

Why does Gentamicin dosage have to be monitored

Answer 23

Because of it toxicity

Question 24

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

Answer 24

Gram positive infections

Question 25

What are examples of Macrolides

Answer 25

erthromysin | clarithromysin

Question 26

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

Answer 26

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

Question 27

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

Answer 27

Daptomycin Active against Gram positives and MRSA Used in serious infections

Question 28

How do antibiotics inhibit nucleic acid synthesis

Answer 28

By interrupting the supply of precursors for DNA synthesis

Question 29

What antimicrobials inhibit nucleic acid synthesis

Answer 29

Trimethoprim and Sulphamethoxazole | Fluoroquinolones

Question 30

What is Co- Trimoxazole

Answer 30

the combined drug of Trimethoprim and Sulphamethoxazole

Question 31

What does Co- Trimoxazole commonly used to treat

Answer 31

Urine infections

Question 32

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

Answer 32

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

Question 33

Who can ciproflaxin not be used on and why

Answer 33

On children can interfere with cartilage growth

Question 34

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

Answer 34

Inability of drug to penetrate the bacterial cell wall

Question 35

What is acquired resistance

Answer 35

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

Question 36

What are the two ways resistance can be acquired

Answer 36

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

Question 37

How does the widespread of antibiotics cause selective pressure

Answer 37

encourages new resistant organisms to outgrow sensitive strains

Question 38

what are b-lactamases

Answer 38

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

Question 39

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

Answer 39

staphylococcus - staph aureas MRSA | resistant to - benzyslpenacillin

Question 40

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

Answer 40

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

Question 41

What is a modified from of penicillin

Answer 41

Flucloxacillin

Question 42

What is the name of gram negative organisms resistant to carbapems

Answer 42

Carbapenemas producing enterobacteriaceae (CPE)

Question 43

CPE organims is worrying because

Answer 43

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

Question 44

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

Answer 44

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

Question 45

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

Answer 45

when bacterias penicilian binding sites are altered

Question 46

What is an example of bacteria with altered penicillin binding protein

Answer 46

MRSA methicin resistant staph aureas

Question 47

What is MRSA resistant to

Answer 47

all penicillins and cephalosporins

Question 48

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

Answer 48

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

Question 49

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

Answer 49

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

Question 50

What antibiotic inhibits purine synthesis

Answer 50

trimethoprim