Antibiotic Overview - Antibacterial Flashcards
What are the 4 mechanisms of action of antibacterials?
- Inhibit of cell wall synthesis
- Inhibit translation & transcription
- Inhibit DNA synthesis & integrity
- Inhibit folate synthesis & fxn
What is the MOA of bactericidal drugs?
Inhibit cell wall synthesis
- Time-dependent killing
- Concentration-dependent killing
What is the MOA of bacteriostatic drugs?
Inhibition of protein synthesis
Describe the post-antibiotic effect
Persistent suppression of bacterial growth after limited exposure to an antimicrobial agent
What is the mechanism of the post-antibiotic effect?
- Slow recovery after non lethal damage to cell
- Persistence of the drug at the binding site
- Need to synthesize new enzymes before microorganism growth can resume
What are examples of narrow spectrum penicillin?
- Penicilinase- susceptible: Penicillin VK
- Penicillinase-resistant: Nafcillin
What is an example of a wider spectrum penicillin?
- +/- penicillinase inhibitor:
Amoxicillin
What is narrow spectrum penicillin used for? (What organisms?)
Staph & strep
What is wider spectrum penicillin used for?
Greater activity vs. gram-negative bacteria
What is 1st generation cephalosporin used for? (Cephalexin)
Skin, soft tissue, UTI
What is 2nd generation cephalosporin used for? (Cefuroxine)
- S. pneumoniae & H. influenza
- B. fragilis
What is 3rd generation cephalosporin used for? (Ceftriaxone, cefixime)
- Pneumonia, meningitis, & gonorrhea
* Beta-lactamase stable
What is 4th generation cephalosporin used for? (Cefipime)
Pseudomonas
What is 5th generation cephalosporin used for? (Ceftaroline)
- Skin, soft tissue
- CAP
What is unique about 1st generation cephalosporin?
- Cross sensitivity w/ PCN
- Contaminated w/ PCN in the past –> cross-reactivity in PCN-allergic pts
When is 2nd, 3rd, 4th, & 5th generation withheld?
If pt suffered TRUE penicillin-induced anaphylaxis
- But they can usually be given safely to penicillin-allergic pts
Describe synergism.
Inhibitory or killing effects of 2 or more antimicrobials used together are greater than expected when used individually
What is synergism marked by?
Fourfold or greater reduction in MIC or MBC of each drug when used in combo vs. alone
Describe empiric tx.
Antimicrobial agent is used before pathogen is identified for particular illness or susceptibility is known
Describe guided tx.
Antimicrobial agent identified by susceptibility testing
What is an antibiogram?
Report of susceptibility/resistance of pathogens to antibiotics
What does an antibiogram provide info about?
Local resistance patterns
What is an antibiogram used to determine?
Empiric tx options
Which meds require dosa adjustment in renal impairment?
- Aminoglycosides
- Carbapenems
- Cephalosporins
- PCNs
- Trimethoprim-sulfamethoxazole
- Vanco
Which meds are contraindicated in renal impairment?
- Nitrofurantoin
- Sulfamides (long-acting)
- Tetracyclines
Which meds require dose adjustment in hepatic impairment?
- Chloramphenicol
- Clindamycin
- Erythromycin
- Metronidazole
What is in common btwn PCN & cephalosporin?
Linked to a side chain
