Introduction to Antimicrobials Flashcards
Symptoms of severe allergic reaction =
> Anaphylaxis > Urticaria (Hives) > Angio-oedema > Bronchospams > Severe skin rash
What is the major component of bacterial cell wall?
Peptidoglycan.
What do Quinolones and Fluroquinolones do?
Inhibit enzymes DNA Gyrase and Topoisomerase IV. (END IN FLOXACIN)
GENERAL Adverse Effects include:
> Nausea, vom, headache > Allergic and Infusion > Anti'b resistance > Fungal infection - C.diff > Ototoxicity (ear) > Renal impairment
What is Peptidoglycan made from?
Hint : Gly –> Think Glucose
Polymer of:
> NAM = N-acetyl Muramic Acid.
> NAG = N-acetyl glucosamine.
What anti’bs commonly cause C.Diff?
Hint: Think “C”
> Cephalosporins
Ciprofloxacin (Quinolones and Flouroquinolones)
Clindamycin
Define: Synergism (antimicrobials)
Activity of two antimicrobials together = greater than their individual activity.
How do aminoglycosides work?
Bind to 30S subunit.
What is Co-trimoxazole made up of?
> Trimethoprim
> Sulfamethoxazole
What is an example of a plasma membrane agent?
Daptomycin.
Antibacterial Mechanisms target what kind of cells?
Enzymes & other critical processing cells.
Aminoglycoside adverse effect =
Reversible renal impairment.
How do Tetracyclines work?
Bind to 30S subunit.
Think “T’s” !!
> –I RNA TRANSLATION
> Interfere with tRNA bind to rRNA.
What drug can you use in pt’s with severe penicillin allergy?
AZT (Monobactam)
What forms 70S initiation complex?
50S and 30S.
What component do animal cell walls lack?
Peptidoglycan –> good for selective toxicity.
When should single dose anaphylaxis be used?
Surgical Prophylaxis.
Determinants of Bacterial Killing are:
Concentration and Time Dependant where Anti’b > MIC.
Conc Dependant = Aminoglycosides
Time Dependant = B-lactams
Examples of cell wall synthesis inhibitors?
> Beta-lactams - MAIN ANTIBIOTIC.
> Glycopeptides
What type of spectrum do Carbapenems have?
Very Broad.
Stages of bacteria protein synthesis?
> Initiation
Elongation
Termination
Ribosome recycling
What type of bacteria do Monobactams only work on?
Gram-negative bacteria.
> AZT
Less commonly precipitating anti’bs to C.diff?
> Aminoglycosides
> Glycopeptides
What does Trimethoprim treat?
UTI’s.
How do Macrolides, Lincosamides Streptogramins (MLS) work?
Bind to 50S subunit - inhibit protein elongation.
ALL END IN MYCIN
What is a common feature of all B-Lactams?
B-lactam ring - Analogue of D-alanyl-D-alanine.
Antibiotic is also known as?
Anti-bacterial agent.
Define: Antibiotics
Chemical products of microbes –> kill/inhibit other organisms.
What does Glycopeptide binding prevent?
Transpeptidase binding –I Peptidoglycan cross-linking.
What does Rifampicin target?
RNA Polymerase –I Stop mRNA forming.
Linezolid adverse effect =
Bone marrow depression
What does Bacteriostatic mean?
Inhibit bacteria growth/division –I Protein synthesis.
What are Aminoglycosides?
Protein synthesis inhibitors.
> Gentamicin, Amikacin
How do Glycopeptides work?
Bind to D-Alanyl-D-Alanine (B Lactam Ring) on NAM - Peptidoglycans.
What drugs can you use in pt’s with minor penicillin allergy?
Carbapenems and Cephalosporins.
Define: Selective Toxicity
Toxic to bacteria, not to host.
- Attack target present in bacteria, not in human.
- Attack significantly different target in human host.
Where does protein synthesis in bacteria occur?
Ribosome.
B-lactams adverse effect =
ALLERGIC REACTION
General = ~10%
Anaphylaxis = 0.01%
What does a Ribonucleoprotein complex consist of?
2/3 RNA, 1/3 Protein
What strain of C.Diff causes severe disease?
Hypervirulent strain 027.
What do enzymes DNA Gyrase and Topoisomerase IV do?
Supercoiling/strand seperation - DNA remodelling during replication.
Define: Indifference (antimicrobials)
Anti’m activity unaffected if another added.
Synergism - Streptococcal endocarditis therapy. Which drug combo?
Beta-lactam & Aminoglycoside.
What does Trimethoprim target?
Dihydrofolate Reductase.
Which types of bacteria have peptidoglycan?
Gram +ve and Gram -ve.
What does Bactericidal mean?
KILL Bacteria –> Cell wall - active agents.
What type of bacteria do Glycopeptides work on?
ONLY Gram +ve.
> Can’t penetrate Gram -ve outer membrane.
What type of spectrum do Penicillins have?
Narrow.
What do Sulphonamides target?
Dihydroperoate Synthetase
What most commonly causes anti-b assc diarrhoea?
C.Difficile Infection –> make toxins A/B.
Define : Minimum Inhibitory Concentration
MIC = Minimum anti’b concentration @ which visible growth inhibited.
What is Benzylpenicillin?
A Beta Lactam.
How do Oxazolidinones work?
Bind to 50S (maybe 70S) –I Protein synthesis.
–I Initiation complex forming.
How do Plasma Membrane Agents work?
CYCLIC LIPOPEPTIDE- Have lipophilic tail and peptide ring.
> Insert tail into membrane –> depolarise –> ion loss
> Gram +ve only.
What type of spectrum do Cephalosporins have?
Broad.
Define: Antagonism (antimicrobials)
One agent diminishes another’s activity
How do B-Lactams work?
They interfere with penicillin binding proteins.
> Transpeptidase enzymes involved in peptideoglycan cross linking.
What do Trimethoprim and Sulphonamides inhibit?
Folate synthesis (Folid acid = Purine synthesis precursor)
Combination Therapy reasons =
> Synergistic combination
Polymicrobial infection
Sepsis treatment
Reduce resistance, anti-TB chemo