Principal Of Antibiotics

Question 1

How is antibiotics classified?

Answer 1

1. Type of activity
2. Structure
3. Target site for activity

Question 2

What are the two type of antibiotic activity?

Answer 2

Bactericidal and bacteriostatic

Question 3

What is bactericidal antibiotics

Answer 3

Bactericidal is when the antibiotic kills the bacteria and it is usually used when the host defence mechanism are impaired. Normally used in endocarditis and kidney infection.

Question 4

What is bacteriostatic antibiotics

Answer 4

Bacteriostatic antibiotics inhibit bacteria and work with the host defence mechanism to combat infections. It stops bacteria from growing but it doesn’t work on more dangerous and fast acting bacteria such as pneumonia as you want something fast acting

Question 5

What are the two spectrum of antibiotics?

Answer 5

Narrow and broad.

Question 6

What is cedotaxime?

Answer 6

It is a broad spectrum antibiotic

Question 7

What is penicillin g

Answer 7

It is a narrow spectrum antibiotic

Question 8

Name some examples of antibiotics that work on the cell wall.

Answer 8

Penicillins , cephalosporins and vancomycin

Vancomycin is used to treat MRSA

Question 9

What does quinolone do?

Answer 9

It act on the DNA gyrase to stop DNA-directed RNA polymerase

Question 10

What does rifampin do?

Answer 10

It act on mRNA

Question 11

What does chloramphenicol do?

Answer 11

It is a drug that act on the ribosome such as the 5os inhibitors, it is prescribed for conjunctivitis.

Question 12

What does tetracycline do?

Answer 12

It acts on the 3os part to prevent protein synthesis.

Question 13

What does polymyxins do?

Answer 13

They act on cell membrane, however it is very toxic and it can affect host cell membranes as well.

Question 14

What is gram positive?

Answer 14

In gram positive you have a very thick layer of cell Wall and a inner membrane layer.

Question 15

What is gram negative?

Answer 15

They have a smaller polydoglycan membrane on the outer layer but they also have another layer of phospholipid bilateral over it which is very selective permeable with potions.

It is more difficult for antibiotics to get trough the phospholipid layer to act on the cell wall.

Question 16

How does bactracin work?

Answer 16

It prevent the dephosphorylation of phospholipid carrier which prevent the regeneration of the carrier for synthesis to continue.

Question 17

How does cycloserine work?

Answer 17

It block alanine addition to form the precursor to the monomer that makes up the cell wall.

Question 18

How does vancomycin work?

Answer 18

It presents the incorporation of subunit into growing peptidoglycan.

Question 19

What is the common function between penicillin and cephalosporin?

Answer 19

They bind and inhibit enzymes that form cross link between the cell wall to prevent growing peptidoglycan.

Question 20

How does beta lactama work on penicillin binding Protein or transpeptidase

Answer 20

Beta lactam diffuses through the potion and bind to the penicillin binding protein and transpeptidase and this inhibit the induction of auto lyric enzymes and this disrupts the peptidoglycan.

They do not work on gram positive

Question 21

Does antibiotics have any other use than to treat infections?

Answer 21

No it can also be used prophylactically to prevent infections. You can give it during peri-operative cover for gut surgery.

Question 22

Why do we use IV for antibiotics?

Answer 22

Because it produce tepid delivery and high blood concentration so it’s more effective against more serious infections.

You can also give intramuscular in cases of meningitis

Question 23

What are topical antibiotics used for?

Answer 23

Conjunctivitis, superficial skin infections, burns.

Examples are antiseptic cream and heavy metal ointments

Question 24

Do we give antibiotic combinations?

Answer 24

Yes we give it to patients with life threatening infections before the exact microorganism is identified.

In can also be given in polymicrobial infections such as abcess, GI perforation anaerobes and aerobes

However the individual drugs that are given as a combination needs to be less toxic and synergy is also nice to have. Such as penicillin and gentamicin

Question 25

Why do we use empirical therapy for antibiotics?

Answer 25

If we don’t have the lab result showing us which microorganism caused it we need to use our best educated guess using symptoms and prescribe what we think will work.

Question 26

What are the three stages of antibiotic therapy?

Answer 26

Stage one is given the first two days when the clinical information is unstable so you are not sure about the type of infection and pathogen so you use an empirical and parenteral treatment.

Stage 2 is when the pathogen is stable and having the site and pathogen identified, this is usually between 2-7 days

Rationalised therapy and parental monotheist occurs next.

Question 27

What cause failure of antibiotic therapy?

Answer 27

Inappropriate drug prescription

Improper route of admission

Inadequate dose

Increase drug excretion than anticipated

Host could be immunocompromised

retained infected body

Host could have poor circulation or damaged tissue

Bacteria could have acquired natural resistance.

There could be dual infection

Laboratory error in identifying the bacteria