Antimocrobial Therapy Flashcards
Ideal characteristics for antibiotics
Selective toxicity, slow emergence of resistance
How do you select antibiotics
By working out the likely pathogen is and susceptibility to specific agents, antimicrobial resistance patterns, PharmaKinetics and patient factors
What is bad about broad-spectrum antibiotics
They have a higher risk of resistance and side-effects
What is empirical treatment
Start antibiotic therapy before knowing the causative microorganism
What is bacteriostatic
It is where the antibiotic stops growth of bacteria and the immune system takes over
What is bactericidal
Where the antibiotic kills the bacteria completely
How do you beta-lactams work
They inhibit cell wall synthesis by inhibiting enzymes which bind the cell wall- peptidoglycan synthesis is inhibited by beta-lactamase
How do you overcome beta-lactamase
You overcome this resistance by using a beta-lactamase inhibitor which is irreversible
What is good about chemically modified penicillin
It has a long half life and can be taken orally and is a broad spectrum antibiotic eg amoxicillin
What is a risk with beta-lactamase
Allergies to penicillin
Amoxicillin is
A broad spectrum antibiotic
Why do you have to be careful of amoxicillin
Allergies and one of the side-effects is gastro intestinal disturbances
What are some examples of beta-lactams
Cephalosporins (broad spectrum)
What do glycopeptides do
Inhibit cell wall, only active in gram positive bacteria and the antibiotic can only be taken by IV not orally
Vancomycin Is only used
Through IV and on gram-positive bacteria, it can be ototoxic
What type of ribosomes do we have
80 S ribosomes which has two subunits 60 S and 40 S
What type of ribosomes do bacteria have
70 S ribosomes with a 50 S and 30 S subunit
How do macrolides work
They inhibit protein synthesis, they can be bacteriostatic and bacteriocidal and a broad spectrum
Clarithromycin
Is a broad spectrum antibiotic, it affects bacteria without and with a cell wall as it works by inhibiting protein synthesis
Side effects of clarithromycin
Nausea, arrhythmias
Aminoglycosides are
Bacteriocidal, nephrotoxicity, ototoxicity 
Tetracyclines are
Broad-spectrum antibiotics that are bacteriostatic
Tetracyclines side effects
Phototoxicity – chelation of metal ions can cause deposition in teeth and bone growth inhibition
What are some examples of inhibitors of DNA replication in antibiotics
Quinolones- inhibit enzymes which leads to rapid bacterial cell death
Metronidazole- which is a pro drug that is bacteriocidal and potentially mutagenic, carcinogenic and teratogenic
Rifampicin- Bacteriocidal, inhibits mRNA synthesis and has a strong induction of CP450
How do antimetabolites work
They look like bacteria metabolite and have a synergistic association and are bacteriocidal
What is synergistic Association
Where the outcome is greater than adding the two components together
1+1=4
Antibiotic resistance due to
Hospital acquired infections, MRSA, too long use or miss use of antibiotics
Resistant mechanisms are either
Inherent so natural or acquired by mutations/ gene transfer
Antibiotics don’t cause
Resistance but they affect the rate of spread
Ways a bacteria becomes resistant
It in activates the antibiotic, alters microbial enzymes, alters target, reduces uptake of antibiotic, develops alternative pathways
How do you stop the spread of resistance to antibiotics
Good medical prescribing
