Peptidoglycan synthesis and antibiotics (microbiology ex 2)

What does bacteriocidal mean?
What does bacteriostatic mean?

Cidal = kills bacteria

Static = stops bacetria from reproducing/growing

Which is reversible which os irreversible? (Static or cidal)

Static = reversible
Cidal = reversible

1.) inhibits ________________ synthesis
2.) inhibits _____________ synthesis
3.) inhibits _______________ synthesis
4.) disrupting the ______________
5.) inhibiting synthesis of essential _______________

Cell wall
Protein
Nucleic acid
Plasma cell membrane
Metabolites

What is step 1 of synthesis of pep cell wall?

Formation of NAM and NAG in the cytoplasma

What is step 2 of synthesis of pep cell wall?

Transglycosylation
Elongates/polymerization NAM and NAG chains

What is 3rd step of pep cell wall synthesis?

Transpeptidation
Cross Links NAM and NAM in the periplsma

What is another name for transpeptidation?

PBP

Does NAM or NAG contain the penta-peptide?

NAM

What does transglycosylation do?

Links NAM and NAG into long chains

What does PBP do?

Cross links NAM and NAM in the periplasmic space

Which amino acid initiates the transpeptidation step?

Serine

Which part of NAM does the transpeptidation target?

D-Ala, D-Ala

After PBP cross links the NAM and NAM, how many D-Alanines does the molecule have?

Only 1

Where do beta Lactam drugs target?

PBP
Transpeptidation step

Where do non beta Lactam drugs target?

D-Ala, D-Ala

How do beta Lactam work, what is the MOA?

Beta Lactam have D-Ala, D-Ala structure

PBP accidentally binds to the beta Lactam irreversibly which prevents the cross linking of NAM and NAM (the final step)

How do Non beta Lactam work? What is the MOA?

They shield the D-Ala, D-Ala on the NAM which prevents the cross linking of NAM and NAM

Defined as ≥3 log10 CFU/mL reduction in growth at 24 hours

Bactericidal

Defined as <3 log10 UFC/mL reduction in growth at 24 hours

Bacteriostatic

Broad and narrow spectrum are determined by the drugs ________

Structure

Bactericidal and bacteriostatic are determined by the drugs ___________

MOA

Beta Lactam s have primary action by __________ inhibition of PBP

Suicide

Because PBP irreversibly binds to beta Lactam rather than cross linking NAM and NAM

Are beta Lactam cidal or static?

Cidal

Glycopeptide

Vancomycin

What is different about lipoglycopeptide antibiotics?

They target gram + bacteria

What does the lipophilic side chain help with?

Increasing their half life

What is the MOA of vancomycin (non beta Lactam drug)

"Caps" the D-Ala, D-Ala to prevent cross linking by PBP

Which kind of bacteria does daptomycin target?

It has a lipid tail, what is that used for?

Gram +

To bind to the cell membrane

What is the MOA of daptomycin?

Is daptomycin cidal or static?

Binds to cell membrane with its tail and causes depolarization

Cidal

What kind of bacteria do polymyxin's target?

Gram -

What is the MOA of polymyxins?

Are polymyxin cidal or static?

Binds to lipid A of LSP, distrusts the cell membrane causing it to leak

Cidal

What kind of ribosomes do bacteria have? (Numbers)

50s and 30s (total 70s)

Which 5 drugs target 50s?

Macrolides
Lincosamides
Streptogramins
Amphenicols
Oxazolidinones

Which 2 drugs target 30s?

Tetracyclines
Aminoglycosides

What type of bacteria do tetracyclines attack?

Both gram + and -

What is the MOA of tetracyclines?

Are they cidal or static

Binding to 30s, block step one (tRNA from entering)

Static

What type of bacteria do aminoglycosides attack?

Gram -
Aerobes

What is the MOA of Aminoglycosides?

Is it cidal or static?

Bind to 30s

Cidal

Do aminoglycosides target:
1.) gram + or gram -
2.) aberobes, anaerobes, facultative

Gram -
Aerobic

List if the following are cidal or static:
List which subunit it binds to:

Macrolide antibiotics

Static
Binds to 50s

List if the following are cidal or static:
List which subunit it binds to:

Lancosamide

Static
Binds to 50s

What is significant about streptogramins?

Where do they bind
Is it static or cidal?

Binds to 50s

Alone = static
Combo therapy = cidal

List if the following are cidal or static:
List which subunit it binds to:

Amephenicols

Static

Binds to 50 s

List if the following are cidal or static:
List which subunit it binds to:

Oxazikidinones

Static

Binds to 50s

Which drug class targets topoisomerase?

Fluoroquinolones

Where do Fluoroquinolones target?

DNA topoisomerase

Which Fluoroquinolones are used for gram +
Which are used for gram -?

Gram + = newer generations (Moxifloxacin)

Gram - = older generation (Ciprofloxacin)

Which topoisomerase do gram + target?

Topoisomerase IV

Which topoisomerase do gram - target?

Topoisomerase II

What does topoisomerase II do?
What does topoisomerase IV do?

II = unwind DNA

IV = separate DNA

Are fluoroquinolones bactericidal or bacteriostatic?

cidal

Which 2 drugs target RNA polymerase?

Lipiramycin
Rifamycin

Are lipramycin and rifamycin cidal or static?

Cidal

What 2 drug classes target folate synthesis?

Sulfonamides
Benzylpyrimidines (trimethroprim)

What do sulfonamides target?

Dihydropteroate synthetase

What does benzylpyrimidines target?

Dihydrofolate reductase

When sulfonamides and benzylpyrimidines are used, are they cidal or static?

If used together = cidal

If used alone = static

What is the ratio of sulfonamides and benzylpyrimidines

Sulfa 5
Trimethoprim 1

1:5

Which antibiotic targets anaerobes?

Nitroimidazole