Antimicrobial Therapy - Allman Flashcards
Bactericidal agent
penicillin, cephalosporin
Bacteriostatic agent
sulfonamides
Narrow Abx
Pen G, Nafcillin
Broad Abx
Piperacillin/Tazobactam
Imipenem
Synergy
Trimethoprim/sulfamethoxazole
sequential inhibition of folic acid synthesis
Synergy
Penicillin/Aminoglycoside
Increased penetration of aminoglycoside as penicillin breaks down cell wall
- enterococcus
Different site for mechanism of action
- psudomonas
Antagonism
Bacteriostatic on bactericidal
Post antibiotic effect (PAE)
persistent effect of an antimicrobial on bacterial growth following brief exposure of organism to a drug
- Aminoglycoside and fluoroquinolones
two parts of pharmacodynamics
Concentration and time dependent killing
Concentration dependent killing
- peak concentration
- optimal when conc exceeds 10x MIC
Quinolones, Aminoglycoside (AMG)
Time dependent killing
amnt of time [ ] stays above MIC (40-50%)
B-lactam Abx
Inhibitors of Cell Wall synthesis
Penicillin/Cephalosporins/Carbapenems/Aztreonam
Vancomycin
Bacitracin
Cycloserine
Penicillin/Cephalosporins/Carbapenems/Aztreonam
Prevents cross linking of peptidoglycan strands by inhibiting transpeptidases
Vancomycin
inhibits peptidoglycan synthetase and polymerization of linear peptide
Inhibitors of protein synthesis/structure
AMG Chloramphenicol Erythromycin/clindamycin/lincomycin Tetracyclines Streptogramins/Linezolid
AMG
inhibits 30 S ribosome
Causes misreading of mRNA
Chloramphenicol
inhibits peptidyl transferase and peptide band formation
Erythromycin/clindamycin/lincomycin
inhibits 50 S ribosome
Tetracyclines
inhibits binding of aminoacyl tRNA to ribosome
30 S ribosome
Streptogramins/Linezolid
23 S ribosome
Interference with Cell Membrane function
Polymixin B, Colistin
Fungal: Azole and polyene antifungals
Polymixin B, Colistin
Cationic detergent
Interference with DNA/RNA synthesis
Rifampin
Fluoroquinolones
Rifampin
inhibits DNA-dependent RNA polymerase
Fluoroquinolones
Interferes with supercoiling of DNA by action on DNA gyrase (topoisomerase II)
Inhibitors of Metabolism
Isoniazid, ethambutol
Sulfonamides, trimethoprim
Isoniazid, ethambutol
Inhibits lipid synthesis
Sulfonamides, trimethoprim
Prevents synthesis of folic acid
Empiric therapy
Culture site before starting Abx
Gram stains - very informative for selection of empiric Abx
Distribution of Meningitis
Penetration into CNS when meninges are inflammed vs uninflammed
Ceftriaxone vs Unasyn
Considerations for drug distribution
Urine concentration
Bone penetration
Lung Tissue penetration
Skin and soft tissue concentration
Example of concurrent medication inference with abx
Antacids with quinolones and tetracycline
Examples of abx inference with concurrent agent
- Bactrim or erythromycin with warfarin
- ciprofloxacin with theophylline
- Linezolid with SSRIs
microbial resistance results from
environmental exposure to Abx
mutation
adaptation
gene transfer
multiple resistance – plasmids
can develop during therapy or is intrinsic
Mechanisms of Resistance
- Increased drug inactivating enzyme activity
- Alter cell wall/membrane permeability
- altered binding site/receptor of drug
- drug efflux
- increase endogenous metabolite
Dose related toxicities for
Imipenem
Amphotericin
Cefazolin
Imipenem - seizures
Amphotericin - nephrotoxicity
Cefazolin - Neutropenia (dose and duration)
Idiosyncratic reaction for:
chloramphenicol
aplastic anemia
What should be used for Abscess?
Antibiotic therapy (not enough) Drainage of area
Superinfection
alt normal flora from removal of inhibitory influences in the body
- due to broad spectrum abx
- enterobacteriaceae (PEK, SE)
- Candida spp.
- Clostridium difficile (Psuedomembranous colitis)
Which abx gets inactivated by lung surfactant?
Daptomycin
Where is the highest concentration of Abx found?
Urinary concentration
