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30 Cards in this Set
- Front
- Back
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What is the most common mechanism of action of antibiotics?
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Inhibiting cell wall synthesis
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Are bacteriostatic mechanisms of action reversible?
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YES
bacteriostatic --> reversible |
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Are bactericidal mechanisms of action irreversible?
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YES
BACTERICIDAL --> IRREVERSIBLE |
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Why should you consider culture and sensitivity assays?
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Bacterial susceptibility --> directly related to antimicrobial efficacy
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What is Larry Sutton's Law?
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Antimicrobial agents must get to the site of infection
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Why does rate of elimination matter?
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Renal or Hepatic dysfunction --> requires dose modification
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What are some examples of antagonism?
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Penicillin plus Macrolides
Penicillin plus Tetracyclines |
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By how much should the minimal drug
concentration exceed the MIC? |
8:1 to kill 99.9% of bacteria
(if MIC is .1 --> give .8) |
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What is the exception when it is OK to give
sub-inhibitory (less than MIC) concentrations? |
To enhance host immune defenses
(allows resolution of infection at lower doses) |
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What must be intact in order for
bacteriostatic antibiotics to be effective? |
HOST DEFENSES
necessary for bacteriostatic to work! |
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What is a post-antibiotic effect?
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Killing of bacteria continues after antibiotics are removed
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How do antibiotics w/ post-antibiotic effects usually work?
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By binding to functional molecules w/in organism
--> RIBOSOMES |
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What is unique about aminoglycoside toxicity?
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Both time and dose dependent!
*use bolus dosing and monitor trough levels |
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What is antibiotic synergy?
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Combinations of antibiotics are more
effective than the sum of each one alone |
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What is an example of antibiotic synergy?
How does it work so well? |
Ampicillin and aminoglycoside
B-lactam breaks hole in cell wall --> aminoglycoside enters and binds to ribosome |
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What are three examples of antibiotic synergy?
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Sequential blockade (TMP-Sulfa)
Block drug inactivating enzyme (Clavulanic acid) Enhance uptake or action of a second antimicrobial (Ampicillin-Aminoglycoside) |
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What is the history of Antibiotic resistance?
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Sulfa --> Penicillin --> Methicillin --> Amoxicillin --> Vancomycin --> Multi-drug
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What are multidrug-resistant GRAM NEGATIVE bacteria?
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Contain genes to induce Extended Spectrum Beta-lactamases (ESBLs)
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Can ESBLs be blocked by Clavulanic acid
or other Beta-lactamase inhibitors? |
NO, cannot be blocked
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What drugs do MDR gram negative bacteria inactivate?
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May inactivate all penicillins, cephalosporins,
monobactams, and rarely carbapenems |
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What pathogens are considered MDR bacteria?
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Enterobacter, Citrobacter,
Serratia, Pseudomonas, Klebsiella, Acinetobacter, and Salmonella |
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What else do ESBL plasmids carry resistance genes for?
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Aminoglycosides, Quinolones, and Sulfonamides
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What are the 5 mechanisms of microbial resistance?
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1. Production of antibiotic inactivating enzymes (Beta lactamases)
2. Changes in target structure (PBPs) 3. Increased efflux via drug transporters 4. Decreased microbial membrane permeability 5. Changes allowing organism to bypass metabolic steps |
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What are the drug transporters that increase the
efflux of drugs out of bacteria referred to as? |
Tetracycline efflux proteins
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What is an example of microbial resistance involving decreased membrane permeability to drugs?
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Loss of IMIPENEM channels in Pseudomonas
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What is an example of microbial resistance
that involves bypassing metabolic steps? |
Changes in folic acid synthesis
--> resistance to Sulfonamides and Quinolones |
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What 4 strategies combat microbial resistance?
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1. ADJUNCTIVE AGENTS to protect against antibiotic inactivation
2. antibiotic COMBINATIONS 3. DEVELOPMENT of new antibiotics 4. AVOIDANCE OF MISUSE! |
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What are 4 examples of protected infection sites?
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CNS, abscesses, urinary tract, adrenal cortex
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What is a general rule regarding patient compliance?
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the more times a day they have to take the medicine
the LOWER THE % COMPLIANCE! |
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What is the solution to improve patient compliance?
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Corporal punishment...
no but really it's LONGER HALF LIVES SO LESS DOSES A DAY |
