Lecture 5 Flashcards
What are three forms of Abx synergism?
- Block sequential steps
- Facilitate drug entry (this is done by cell wall or membrane inhibitors)
- Inhibit a drug detox enzyme
What is an example of syergism?
Loperamide and Tet allow entry of each other
Example of Abx antagonism?
Chloramphenicol and PCN If chloramphenicol acts first, it is bacteriostatic and PCN can’t kill
What is SxT
Sulmethoxazole/Trimethoprim (Septra and Bactrim)
What structural congregation of bacteria are very difficult to kill?
Biofilms
When should you use multiple Abx?
System infection To delay resistance in long-term use For synergism
What is Synercid?
Quinupristin and dalfopristin Together are bacteriocidal
What is the best treatment for biofilms?
Prevention
How are new coatings on implantable devices working to inhibit biofilms?
Kill with cationic detergent and then hydrolyze
Beta lactam mode of action
Cell wall inhibitors by:
Inhibiting transpeptidation
Activate autolysins
Causes of beta lactam resistance?
Beta lactamases
Lack of PBPs (PCN binding proteins)
Autolysin mutations
Common beta-lactamase inhibitors?
Clavulinic acid
Sulbactam
Tazobactam
What are the natural forms of PCN?
Pen G
Pen V
Use for natural PCNs?
GramPos
What forms of PCN are beta-lactamase resistant? What is their weakness?
Nafcillin
Oxacillin
Cloxacillin
They have lower activity
What is spectrum of expanded spectrum PCNs?
GramPos
GramNeg
What are the expanded spectrum PCNs?
Ampicillin
Piperacillin
Mezlocillin
Ticarcillin (vs. pseudomonas)
What are the acid resistant PCNs?
Amoxycillin
Pen V
Oxacillin
What is ampicillin often paired with?
Sulbactam
What is zosyn, tazomed?
Piperacillin + tazobactam
What is a benefit of cephalosporins?
Less sensitive to beta-lactamases
What are the classes of beta-lactams?
PCNs
Cephalosporins
Carbapenems
Monobactams
1st gen cephalosporin spectrum?
GramPos
For prophylatic use only
1st gen cephalosporins?
Cephalexin
Cephalothin
Cefazolin
2nd gen cephalosporin spectrum
GramPos and GramNeg
Will cover bacteroides
Does not cover pseudomonas
2nd gen cephalosporins
Cefaclor
Cefuroxime
Cefoxitin
3rd gen cephalosporin spectrum
GramPos, GramNeg, and pseudomonas
Used for GramNeg only to protect against overuse
3rd gen cephalosporins
Ceftazidime
Cephotaxime
Cephtriaxone
4th gen cephalosporin spectrum
Slight expanded from 3rd gen
Monobactam spectrum
GramNeg only!
No GramPos or anaerobes
4th gen cephalosporin
Cefepime
5th gen cephalosporins spectrum
Activity against MRSA and drug resistant S. pneumoniae
5th gen cephalosporins
Ceftaroline
Benefit of monobactams
Resistant to beta-lactamases
Monobactam example
Aztreonam
Carbapenem spectrum
Broad
GramPos and GramNeg
Risk of carbapenems
May be toxic –> seizures
Carbapenem examples
Imipenem, ertapenem, meropenem
Meropenem benefit
Might be less toxic than other carbopenems
What is a side effect of cephalosporins
Might cause thrombophlebitis
Who might experience a PCN rash?
Someone infected with mono virus
Bacitracin mode of action
Blocks de~P of bactoprenol
Bacitracin spectrum
Topical only because renal toxicitiy, poorly absorbed
GramPos (commonly used with others)
Glycopeptide Abx examples?
Vancomycin
Telavancin
Glycopeptide Abx mode of action?
Bind to amino acid side chain
Block transglycosylation and transpeptidation