Growth Control Flashcards
Microbial Growth Control
-chemical microbial growth control
Chemical Microbial Growth
-Bacteriostatic agents (fungistatic and viristatic)
-Bacteriocidial agents (fungistatic and viristatic)
-Bacteriolytic
Bacteriostatic
-graph x: time, y: log cell number
-viable cells count positive line then straightens out (/-)
-total cell count same as viable cell count
Bacteriocidial
-graph x: time, y: log cell number
-viable cells count triangle shape (^)
-total cell count same as viable but straightens out at triangle point (/-)
Bacteriolytic
-graph x: time, y: log cell number
-viable cells count triangle shape (^)
-total cell count same as viable (^)
Measuring Antimicrobial Activity
-Minimum Inhibitory Concentration (MIC) (in liquid medium)
-Agar diffusion method/zone of inhibition (on plates)
Chemical Microbial Growth Control: Classifying Antimicrobial Treatments
-Sterilant
-Disinfectants
-Sanitizers
-Antiseptics/Germicides
-Concentration and exposure time are important!
Sterilants
-kills microorganisms including endospores
Disinfectants
-kills microorganisms NOT including endospores
Sanitizer
-Reduce microorganisms numbers, but are relatively nontoxic and used in food preparation setting
Antiseptics/Germicides
-kill or inhibit growth of microorganisms, but are nontoxic to living tissues (your skin)
Development and Spread of Antimicrobial Drug Resistance
-The facts of resistance: It has and will continue to happen
Mechanisms of Resistance: What makes a bacterial cell resistant?
-Naturally resistant (no target or impermeable)
-chemical alteration of antibiotic
-pump antibiotic out of cell
-modify target of antibiotic
Development and Spread of Antimicrobial Drug Resistance: What factors allow a cell to change from sensitive to resistant?
-resistance genes acquired via:
~Chromosomal mutations
~Genetic exchange with naturally occurring resistant organisms in the environment.
Resistance (R) plasmids
Transposons
Development and Spread of Antimicrobial Drug Resistance: What human practices speed the appearance of resistance?
-Medical misuse of antibiotics
-Agricultural misuse of antibiotics
