Principal Of Antibiotics Flashcards
How is antibiotics classified?
- Type of activity
- Structure
- Target site for activity
What are the two type of antibiotic activity?
Bactericidal and bacteriostatic
What is bactericidal antibiotics
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.
What is bacteriostatic antibiotics
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
What are the two spectrum of antibiotics?
Narrow and broad.
What is cedotaxime?
It is a broad spectrum antibiotic
What is penicillin g
It is a narrow spectrum antibiotic
Name some examples of antibiotics that work on the cell wall.
Penicillins , cephalosporins and vancomycin
Vancomycin is used to treat MRSA
What does quinolone do?
It act on the DNA gyrase to stop DNA-directed RNA polymerase
What does rifampin do?
It act on mRNA
What does chloramphenicol do?
It is a drug that act on the ribosome such as the 5os inhibitors, it is prescribed for conjunctivitis.
What does tetracycline do?
It acts on the 3os part to prevent protein synthesis.
What does polymyxins do?
They act on cell membrane, however it is very toxic and it can affect host cell membranes as well.
What is gram positive?
In gram positive you have a very thick layer of cell Wall and a inner membrane layer.
What is gram negative?
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.
How does bactracin work?
It prevent the dephosphorylation of phospholipid carrier which prevent the regeneration of the carrier for synthesis to continue.
How does cycloserine work?
It block alanine addition to form the precursor to the monomer that makes up the cell wall.
How does vancomycin work?
It presents the incorporation of subunit into growing peptidoglycan.
What is the common function between penicillin and cephalosporin?
They bind and inhibit enzymes that form cross link between the cell wall to prevent growing peptidoglycan.
How does beta lactama work on penicillin binding Protein or transpeptidase
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
Does antibiotics have any other use than to treat infections?
No it can also be used prophylactically to prevent infections. You can give it during peri-operative cover for gut surgery.
Why do we use IV for antibiotics?
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
What are topical antibiotics used for?
Conjunctivitis, superficial skin infections, burns.
Examples are antiseptic cream and heavy metal ointments
Do we give antibiotic combinations?
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
