PHARMACOLOGY OF AGENTS THAT TARGET PATHOGENIC ORGANISMS: Mode of Action of Antibiotics

Mode of Action of Antibiotics

Bactericidal

destroys or kills the bacteria

Bacteriostatic

slows down the growth of bacteria

Cell membrane

The first type of antibiotic is the one that targets the _______________

Antibiotics that targets the cell membrane

These antibiotics will disrupt the cell membrane function which means that they disrupt the phospholipid bilayer

cell membrane, phospholipid bilayer

These cell membrane antibiotics will disrupt the ___________________ function which means that they disrupt the ________________________

alter, more permeable

The antibiotic binds to the cell membrane. It will ______ the cell membrane structure and will make it ______________

leakage, increase, cell death

Disrupting the osmotic balance causing ______ of cellular molecules and essentially it will _______ the uptake leading to ________.

polymyxins and polyenes

Examples of Antibiotic drugs that targets the cell membrane

Polyenes

specifically used against fungal pathogens but you can use it also to target some cell membranes in fungi

Antibiotic classes that target the cell wall

These antibiotics will inhibit cell wall synthesis, so these drugs are therefore bactericidal

Penicillin, Cephalosporin, and Bacitracin

Examples of Antibiotics that target the cell wall synthesis.

Penicillin, Cephalosporin, Beta-lactams, Bacitracin, and other glycopeptides

what drugs prevent the synthesis of cell walls?

Cell walls, cell death

_________ are important to bacteria disrupting a cell wall preventing cell wall synthesis will result in _______.

Gram negative bacteria

has thin peptidoglycan and has an outer cell membrane

Gram positive bacteria

has thick peptidoglycan layer but no outer cell membrane.

Peptidoglycan layer

a specific derivative of glucose/ carbohydrates that is made up of NAM and NAG.

Beta-lactams

It is a 5 ring structure and 4 ring structure

Penicillin

• Treats in gram(+) and gram(-)

• Cover Streptococcal bacteria

• Treats syphilis

• Bactericidal

• Certain bacteria become resistant

Autolytic enzymes

Penicillin binds to Penicillin binding protein and stimulates _______________.

transpeptidase, disrupted

Whenever the Penicillin binding protein is stimulated, it inhibits the _____________. Therefore, cell wall is ___________ and water can leak in.

Amoxicillin

• Same MOA with Penicillin

• Susceptible to beta-lactams

• Should give together with clavulanic acid that will inhibit the beta lactamase enzyme

• Treats UTI, Respiratory Infections, meningitis, salmonella, otitis media.

Cephalosporin

• Same MOA with Penicillin

• Treatment for S. aureus, S. pyrogens.

• Tx for Pseudomonas

• Tx for Meningitis

• Tx for Klebsiella (pneumonia)

• Tx for Enterobacteria

• 1st gen: cephalexin

• 2nd gen: cefuroxime

• 3rd gen: ceftriaxone

• 4th gen: cefepime

Name the 4 generations of Cephalosporin

Cephalexin

1st gen of Cephalosporin

Cefuroxime

2nd gen of Cephalosporin

Ceftriaxone

3rd gen of Cephalosporin

Cefepime

4th gen of Cephalosporin

1st and 2nd generation Cephalosporin

What generations of Cephalosporin that mainly treats gram(+) bacteria

3rd and 4th generation Cephalosporin

What generations of Cephalosporin that mainly treats gram(-) bacteria

Vancomycin

• Kills MRSA (Methicillin resistant staphylococcus aureus)

• Treats gram(+) bacteria

• Tx for C. diff (diarrhea)

• Resistant coagulase (bacteria)

• Hinders peptide bond formation

Binds to carboxyl end that can’t form peptide bond

What is the MOA of Vancomycin?

peptide bond formation, disrupted, cell lysis

MOA of Vancomycin: Binds to carboxyl end that cant form peptide bond. It hinder _____________. As a result, the Cell wall will be __________ and water flows in and the ________.

Quinolones and Nalidixic acid

What antibiotic drugs that will inhibit DNA or RNA synthesis

Rifamycin

What antibiotic drug that prevents RNA synthesis and therefore protein synthesis

Protein synthesis

It is carried out typically by ribosomes which translate mRNA into proteins.

True

True or False:

Bacteria needed to make proteins in order to survive

Erythromycin and Chloramphenicol

What antibiotic drugs that target 50s subunit of ribosomes

Tetracycline, streptomycin, and gentamycin

What antibiotic drugs that target 30s subunit of ribosomes

Disrupt, unable to make proteins

Tetracycline, streptomycin, and gentamycin target 30s subunit either way this will ________ the ribosomes from making proteins which will result in bacteria being _____________.

Bacteriostatic

These antibiotics that target protein synthesis are called _____________.

PABA (Para - aminobenzoic acid)

• It is a precursor to folate

• Normally can be metabolized to folic acid within the bacteria

Folic acid or folate

• Essential for the synthesis of adenine and thymine

• 2 of the 4 nucleic acids that make up DNA

Sulfonamide and Trimethoprim

These antibiotics prevent the conversion of PABA to folate and therefore prevent proper DNA synthesis

True

True or False:

Humans do not synthesize folic acid and so these folic acid antibiotics inhibitors are okay to take for humans and are selective towards bacteria