Antibacterials Flashcards
Antibacterial Drugs
Meds used to exploit differences between human cells and bacteria
Can be effective against gram positive or gram negative
Narrow-spectrum effective against one class of bacteria
*Broad-spectrum** effective against both classes of bacteria
Drugs that affect cell wall synthesis
Penicillins
Vancomycin
Cephalosporin
Antibiotic Drugs that affect protein synthesis
Macrolides
Tetracyclines
Aminoglycosides
Drugs that affect transcription mechanisms
Fluoroquinolones
Drugs that affect metabolic pathways
Sulfamethoxazole/Trimethoprim (taken together)
Is Sulfamethoxazole bactericidal or bacteriostatic?
Bacteriostatic
What infections are sulfonamides best for?
UTIs (reaches effective concentration in urinary tract)
Upper respiratory tract infection
What are the 4 B-lactam drugs
Penicillins
Cephalosporins
Carbapenems
Monobactam (not in canada)
Natural vs semi-synthetic penicillins
Natural: sensitive to b-lactamase
Semi-synthetic: b-lactamase resistant, broad spectrum or aminopenicillins
Benefit of aminopenicillins?
Broader spectrum
Are penicillins bactericidal or bacteriostatic?
Bactericidal
Are penicillins effective against gram negative or gram positive?
Gram positive and some gram negative
What acid is a B-lactamase inhibitor?
Clavulanic acid (amoxicillin + clavulanic acid)
Penicillin G vs Penicillin V
Penicillin G is IV or IM
Penicillin V is PO
Cephalosporins
Most widely used antibacterials
Structurally and pharmacologically related to penicillins
B-lactam antibiotics
bactericidal
First gen -> fifth gen. better gram-negative coverage and better B-lactamase resistance in later generations
Cephalosporin: Cefazolin
1st generation (poor gram negative coverage, excellent gram positive coverage - best gen for gram positive)
Used for surgical prophylaxis, URIs, otitis media
IV administration
What happens as the cephalosporin generations increase
Broader coverage
Good gram-positive coverage through all generations, but gram-negative coverage increases with each generation
Carbapenems
B-lactam. Affects cell wall synthesis.
Broad-spectrum
Parentally given only
Drug: Imipenem
a “last resort” antibiotic
Macrolides
Inhibits protein synthesis (binds to ribosomes)
bacteriostatic and bactericidal depending on concentration and bacterial susceptibility
Drug: Erythromycin
Adverse effects: GI disturbances
Azithromycin/Clarithromycin: fewer side effects and better penetration
Tetracyclines
Inhibits protein synthesis (30S ribosomes)
Broad spectrum
Bacteriostatic
binds to metal ions
Dairy, antacids, and iron salts reduce absorption
DO NOT USE in children less than 8yr old, or pregnancy/breastfeeding.
Strong affinity for calcium: discolouration of teeth
Adverse: Alteration in intestinal flora
Non-bacterial action: Demeclocycline for SIADH (syndrome of inappropriate ADH)
Aminoglycosides
Inhibits protein synthesis (30S ribosomes)
1st antibiotic effective against gram-negative bacteria
Bactericidal
Drug: Gentamicine
Poorly absorbed in GI tract. Given IV or IM. But given orally to decontaminate GI tract before surgery
Serious toxic effects: Ototoxicity (irreversible, worse if used with loop diuretics), Nephrotoxicity (reversible). Monitor plasma drug levels
Increased risk for nephrotoxicity (additive effect) if used with vancomycin, cyclosporine, amphotericin
Quinolones/Fluoroquinolones
Alters DNA of bacteria
Broad Spectrum
Bactericidal
Urinary tract infections
Anthrax
Drug: Ciprofloxacin
Very effective and most commonly used. Oral admin.
Adverse Effects: GI, rashes, dizziness
Vancomycin
Inhibits cell wall synthesis
Bactericidal
Different protein targets B-lactams, (so not a B-lactam.)
IV administration for MRSA
Oral for C diff
Adverse:
Infusion-related: red man syndrome
fever, chills, ototoxicity, nephrotoxicity
