Flashcards in Antimicrobial Agents Intro Deck (28):
What are the 3 classes of antimicrobial agents?
T-F--life destroys life among the lower species?
When was penicillin discovered? by who
When was sulfanilamide discovered?
The ideal antimicrobial agent acts selectively on what? What 4 ways is this achieved?
1. the pathogen and not the host
2. unique cell structure, unique biochem paths, altered component affinities, prodrug converted only by pathogen
Review/memorize the 5 factors that determine cidal vs. static activity
1. drug's mechanism
2. microbe's state of growth
3. concentration of drug on organism
4. type of microbe
5. drug's spectrum of activity
What is the general rule of thumb for antibiotics in the blood?
should exceed the
MIC by 2-8X to offset tissue barriers to infection site
What does narrow spectrum antibiotic mean?
mainly effective against G+ or G- microbes, lower risk for superinfections
What does extended spectrum antibiotic mean?
affects a variety of G+ and G- bacteria
What does broad spectrum antibiotic mean?
Affects both G+ and G-, and other organisms
Are all the broad spectrum antibacterials bacteriostatic or bactericidal?
What reflects the margin of
safety expected when using an antimicrobial agent
at its effective dose?
Does clinical effectiveness depend on maximal efficacy more or less than potency?
Review the list of factors influencing efficacy
1. Host-immune function, pharmacokinetics, age, preg, genetics, allergy, eidemiologic exposure, compliance
2. Microbe-type and variability, body burden, growth rate, environment/site
3. drug drug interaction- synergy, antagonism, PK effects
What are the 3 reasons for antimicrobial drug resistance?
2. inherent microbial resistance
3. Acquired microbial resistance
What are the 3 ways microbial resistance is acquired?
a. Drug fails to reach target
b. Drug is inactivated
c. Drug target is altered
What are the common ways of genetic drug resistance? non-genetic?
1. chromosomal resistance, sex-plasmid and transposon mediated (transformation, transduction, conjugation)
2. growth latency, anaerobic conditions, protoplasts
Review some epidemiology of resistance problems
2 million patients get infection in hospital--90,000 of them die
-70% of bacteria causing infections are drug resistant
What are the 3 major drug resistant bacteria?
strep pneumoniae, MRSA, VRE
What are 4 methods of avoiding drug resistance?
1. use only when needed
2. select the best antibiotic for the organism
3. use doses to establish effective concentrations for effective times
4. Use multiple drug therapy only when indicated
When is combination antimicrobial therapy valid? 4
1. severe infection of unknown cause
2. polymicrobial infections
3. enhancement of antibacterial effects in treatment of specific infections
4. prevent emergence of resistant microorganisms
What are the 3 potential results of combination antimicrobial therapy?
What are the 2 main characteristics of antagonism between drugs?
a. Cidal plus static agents
b. Metabolizing enzyme induced
What are the 3 main types of synergy in combination antimicrobial therapy?
a. Blockade of sequential steps in pathway
b. Inhibition of drug-inactivating enzyme
c. Enhancement of drug uptake
What are the 3 main disadvantages of combination antimicrobial therapy?
3. Selection for drug-resistant bugs
INCREASED COST TOO
Prophylaxis represents 30-50% administered antibiotics in the US. When is prophylaxis commonly used?
1. pre-surgery in patients with indwelling medical devices
2. prevent wound infection following surgery
3. sexual contacts of patients with STDs
Review the general considerations for appropriate antibiotic use?
1. General health of patient (immune function,
severity of infection)
2. Where advisable, narrow spectrum agents
3. Nosocomial infections – drug resistance
5. Cidal vs static
6. Dose alteration
7. Drug delivery
• Oral, parenteral (IV, IM, insoluble salts), topical