Principle 4- Part A Flashcards
: a class of chemotherapeutic agents
Antibiotics
_________ are chemical compounds used to treat disease
Chemotherapeutic agents
______ destroy pathogenic microbes or inhibit their growth within host
Antimicrobials
______ destroy or inhibit bacteria
Antibiotics
_____: artificial means of destroying bacteria, protozoa, viruses, and fungi
Antibiotics
–ability of drug to kill or inhibit pathogen while damaging host as little as possible
selective toxicity
–drug level required for clinical treatment
therapeutic dose
–drug level at which drug becomes too toxic for patient (i.e., produces side effects)
toxic dose
–ratio of toxic dose to therapeutic dose
therapeutic index
_______ antibiotics–kill bacteria
Bacteriocidal
_______ antibiotics–inhibit growth of bacteria
Bacteriostatic
________ antibiotics–attack many different bacteria (Gram + and Gram -)
Broad-spectrum
_______ antibiotics–attack only a few different bacteria
Narrow-spectrum
The Level of Antimicrobial Activity effectiveness is expressed in what two ways?
MIC and MBC
•lowest concentration of drug that inhibits growth of pathogen
minimal inhibitory concentration (MIC)
•lowest concentration of drug that kills pathogen
minimal bacteriocidal concentration (MBC)
What are the two techniques that are routinely used to determine MIC and MBC?
Dilution susceptibility tests and disk diffusion tests
•involves inoculating media containing different concentrations of drug
–broth or agar with lowest concentration showing no growth is MIC
–if broth used, tubes showing no growth can be subcultured into drug-free medium•broth from which microbe cannot be recovered is MBC
Dilution Susceptibility Tests
- disks impregnated with specific drugs are placed on agar plates inoculated with test microbe
- drug diffuses from disk into agar, establishing concentration gradient•observe clear zones (no growth) around disks
Disk Diffusion Tests
- standardized method for carrying out disk diffusion test
- sensitivity and resistance determined using tables that relate zone diameter to degree of microbial resistance
- table values plotted and used to determine if concentration of drug reached in body will be effective
Kirby-Bauer method
concentration of drug at infection site must be _____ than MIC to be effective
Greater than
What are the 3 Factors Influencing the Effectiveness of Antimicrobial Drugs?
- ability of drug to reach site of infection
- ability of drug to reach concentrations in body that exceed MIC of pathogen
- susceptibility of pathogen to drug
What are the 3 modes of administration of drugs?
Oral
Topical
Parenteral
Drugs can be excluded by what 2 things in the body to inhibit it from reaching the site of infection?
Blood clots or necrotic tissue
What are the 4 Factors influencing ability of drug to reach concentrations exceeding MIC?
- amount administered
- route of administration
- speed of uptake
- rate of clearance (elimination) from body
Is a higher or lower therapeutic index better?
Higher
Mechanism of _____ of Antimicrobial Agents can impact pathogen by targeting some function necessary for its reproduction or survival
Action
What do antimicrobial agents that disrupt bacterial cell wall disrupt?
Peptidoglycan structure
