MICR 3050 Exam 3 Questions and
Answers
sterilization - Answer-destruction or removal of all viable organisms
disinfection - Answer-killing, inhibition, or removal of pathogenic organisms
sanitization - Answer-reduction of microbial population to levels deemed safe (based on public health
standards)
antisepsis - Answer-prevention of infection of living
antiseptics - Answer-chemical agents that kill or inhibit growth of microorganisms
chemotherapy - Answer-use of chemicals to kill or inhibit growth of microorganisms within host tissue
-cide - Answer-kills target
-static - Answer-inhibits growth as long as microorganisms are in their presence
Microorganisms die - Answer-exponentially
,Decimal reduction time - Answer-(D value) time to kill 90%
Measures an agent's killing efficiency
Problem with d value - Answer-we measure killing effectiveness by looking at viable cells, but there are
some that are viable but not cultural (VBNC) *would be counted as dead but not*
Conditions that influence the effectiveness of an antimicrobial agent: Population size - Answer-the more
cells we start with, the longer it'll take to kill 90%
Conditions that influence the effectiveness of an antimicrobial agent: population composition - Answer-
1) state of cells (health/dying?)
2) special characteristics: endospore formers, etc;
3) are they in growth phase?
Conditions that influence the effectiveness of an antimicrobial agent: concentration or intensity of the
agent - Answer-where is it most effective?
1) increasing the concentration typically increases effectiveness up to a point where effectiveness is
maxed out
Conditions that influence the effectiveness of an antimicrobial agent: duration of exposure - Answer-
typically the longer time you expose it, the lower the concentration and vice versa
Conditions that influence the effectiveness of an antimicrobial agent: temperature - Answer-general
rule:
the higher the temperature, the higher the effectiveness of an antimicrobial agent
Conditions that influence the effectiveness of an antimicrobial agent: local environment - Answer-1) pH
, 2) oxygen availability
**any time you combine stresses, the more effective
Mechanical method to control microorganisms - Answer-filtration
Physical method to control microorganisms: (5 things) - Answer-1) moist heat
2) dry heat
3) low temperature
4) UV radiation
5) ionizing radiation
Filtration - Answer--reduces microbial population or sterilizes solutions that are heat sensitive
-Also used for air: surgical masks, cotton plugs on culture vessels, high-efficiency particulate air (HEPA
filters), laminar flow biological safety cabinets
-If microbes are bigger than pores, they will be stuck on the filter and separated from liquid or gas
-To sterilize in micro, pores need to be < or = 0.2 micrometers
-Syringe filter and bottle filter: liquid
Moist heat - Answer--destroys bacterial, fungi, and viruses
-DEGRADES NUCLEIC ACIDS, denatures proteins, and disrupts membranes
3 types of moist heat - Answer-Boiling, autoclaving, and pasteurization
Boiling - Answer-Will not destroy endospores, so does not sterilize
Answers
sterilization - Answer-destruction or removal of all viable organisms
disinfection - Answer-killing, inhibition, or removal of pathogenic organisms
sanitization - Answer-reduction of microbial population to levels deemed safe (based on public health
standards)
antisepsis - Answer-prevention of infection of living
antiseptics - Answer-chemical agents that kill or inhibit growth of microorganisms
chemotherapy - Answer-use of chemicals to kill or inhibit growth of microorganisms within host tissue
-cide - Answer-kills target
-static - Answer-inhibits growth as long as microorganisms are in their presence
Microorganisms die - Answer-exponentially
,Decimal reduction time - Answer-(D value) time to kill 90%
Measures an agent's killing efficiency
Problem with d value - Answer-we measure killing effectiveness by looking at viable cells, but there are
some that are viable but not cultural (VBNC) *would be counted as dead but not*
Conditions that influence the effectiveness of an antimicrobial agent: Population size - Answer-the more
cells we start with, the longer it'll take to kill 90%
Conditions that influence the effectiveness of an antimicrobial agent: population composition - Answer-
1) state of cells (health/dying?)
2) special characteristics: endospore formers, etc;
3) are they in growth phase?
Conditions that influence the effectiveness of an antimicrobial agent: concentration or intensity of the
agent - Answer-where is it most effective?
1) increasing the concentration typically increases effectiveness up to a point where effectiveness is
maxed out
Conditions that influence the effectiveness of an antimicrobial agent: duration of exposure - Answer-
typically the longer time you expose it, the lower the concentration and vice versa
Conditions that influence the effectiveness of an antimicrobial agent: temperature - Answer-general
rule:
the higher the temperature, the higher the effectiveness of an antimicrobial agent
Conditions that influence the effectiveness of an antimicrobial agent: local environment - Answer-1) pH
, 2) oxygen availability
**any time you combine stresses, the more effective
Mechanical method to control microorganisms - Answer-filtration
Physical method to control microorganisms: (5 things) - Answer-1) moist heat
2) dry heat
3) low temperature
4) UV radiation
5) ionizing radiation
Filtration - Answer--reduces microbial population or sterilizes solutions that are heat sensitive
-Also used for air: surgical masks, cotton plugs on culture vessels, high-efficiency particulate air (HEPA
filters), laminar flow biological safety cabinets
-If microbes are bigger than pores, they will be stuck on the filter and separated from liquid or gas
-To sterilize in micro, pores need to be < or = 0.2 micrometers
-Syringe filter and bottle filter: liquid
Moist heat - Answer--destroys bacterial, fungi, and viruses
-DEGRADES NUCLEIC ACIDS, denatures proteins, and disrupts membranes
3 types of moist heat - Answer-Boiling, autoclaving, and pasteurization
Boiling - Answer-Will not destroy endospores, so does not sterilize
