Antimicrobial Agents Intro Flashcards
What are the 3 classes of antimicrobial agents?
antibacterialantiviralsantifungals
T-F–life destroys life among the lower species?
True
When was penicillin discovered? by who
1929, fleming
When was sulfanilamide discovered?
1936
The ideal antimicrobial agent acts selectively on what? What 4 ways is this achieved?
- the pathogen and not the host2. 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
- drug’s mechanism2. microbe’s state of growth3. concentration of drug on organism4. type of microbe5. drug’s spectrum of activity
What is the general rule of thumb for antibiotics in the blood?
should exceed theMIC 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?
bacteriostatic
What reflects the margin ofsafety expected when using an antimicrobial agentat its effective dose?
Chemotherapeutic indexTD50/ED50
Does clinical effectiveness depend on maximal efficacy more or less than potency?
maximal efficacy
Review the list of factors influencing efficacy
- Host-immune function, pharmacokinetics, age, preg, genetics, allergy, eidemiologic exposure, compliance2. Microbe-type and variability, body burden, growth rate, environment/site3. drug drug interaction- synergy, antagonism, PK effects
What are the 3 reasons for antimicrobial drug resistance?
- Misdiagnosis2. inherent microbial resistance3. Acquired microbial resistance
What are the 3 ways microbial resistance is acquired?
a. Drug fails to reach targetb. Drug is inactivatedc. Drug target is altered
What are the common ways of genetic drug resistance? non-genetic?
- 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?
- use only when needed2. select the best antibiotic for the organism3. use doses to establish effective concentrations for effective times4. Use multiple drug therapy only when indicated
When is combination antimicrobial therapy valid? 4
- severe infection of unknown cause2. polymicrobial infections3. enhancement of antibacterial effects in treatment of specific infections4. prevent emergence of resistant microorganisms
What are the 3 potential results of combination antimicrobial therapy?
- antagonism2. addition3. synergism
What are the 2 main characteristics of antagonism between drugs?
a. Cidal plus static agentsb. Metabolizing enzyme induced
What are the 3 main types of synergy in combination antimicrobial therapy?
a. Blockade of sequential steps in pathwayb. Inhibition of drug-inactivating enzymec. Enhancement of drug uptake
