Lecture 7 - Infection Control

Question 1

Antiseptic

Answer 1

disinfectant used on the skin [living tissue]

i.e. alcohol hand sanitizer

Question 2

Aseptic technique

Answer 2

use of methods to exclude microorganisms [avoids infection]

Question 3

Bactericidal

Answer 3

kills bacteria

Question 4

Bacteriostatic

Answer 4

inhibits growth of bacteria but does not kill it

Question 5

Disinfectant

Answer 5

chemicals used to destroy many micro-organisms and viruses on surfaces (not on body) (i.e. lysol)

Question 6

Fungicide

Answer 6

kills fungi

Question 7

Pasteurization

Answer 7

brief heat treatment used to reduce the numbers of organisms and to kill pathogenic organisms

Question 8

Sanitization

Answer 8

Reduction of the number of organisms to a level that meets public health standards (wiping off)

Question 9

Sterilization

Answer 9

destruction of all forms of micro-organisms including spores

Question 10

Viricide

Answer 10

inactivates viruses

Question 11

Glutaraldehyge

Answer 11

embalming fluid –> kills all life (sterilization)

Question 12

what kinds of filters are used in operating rooms in the hospital?

Answer 12

High-efficiency particulate air filters (HEPA)

Question 13

what is positive pressure air lock?

Answer 13

air from corridor cant get into patient’s room (this is for patients who are immunocompromised and need to be kept away from everyone else to avoid infection) i.e. right after a bone marrow tx

Question 14

What is negative pressure air lock?

Answer 14

air from room cannot get into corridor (air from patient cant get into hallway and infect (this is for patients who are highly infectious and you want to avoid them making contact with others) i.e. patient with tuberculosis or measles

Question 15

what are 7 ways to control microbial growth?

Answer 15

1. heat
2. filtration
3. cold
4. high pressure
5. desiccation (drying)
6. Osmotic pressure
7. Radiation

Question 16

two ways to achieve sterilization by heating?

Answer 16

1. hot air (160-180 degrees celcius) for 1-2 hours

OR

2. autoclaving (moist heat): 121 degrees Celsius, 15 psi for 15 minutes [more effective]

Question 17

What kind of species’s spores will autoclaving kill?

Answer 17

C.botulinum spores

Question 18

What is a test for effective sterilization?

Answer 18

“spore test” using Bacillus stearothermophilus spores (or any non-pathogenic bacteria spore)
- you take filter paper discs or ampule and put the B.stearothermophilus in/on it, and then place it into autoclave with the object to be sterilized, then you take it out after the time is up (15 mins) and test to see if it shows growth. Growth is indicated by the change in the pH of the ampule growth media (seen as a colour change) as the spore has germinated and the growing vegetative bacteria is using nutrients in the medium and producing acid or alkali compounds. If it does, it means the autoclave is not sterilizing

yields a negative (sterile) or positive (non-sterile) result with the positive test tube being yellow

Question 19

4 ways of achieving sterilization?

Answer 19

1. heat
2. irradiation (gamma or UV)
3. filtration
4. chemicals

Question 20

What is the most important consideration that determines the efficiency of sterilization?

Answer 20

whether or not the object to be sterilized is free of organic matter (i.e. blood, fecal matter, and tissue) and able to withstand heat
- important to wash instrument before sterilizing it (i.e. if blood is caked on the instrument)

Question 21

What are 4 common chemicals used to control growth of microorganisms?

Answer 21

• halogens (chlorine, iodine) –> can sterilize if used well [chlorohexidine is used to sterilize operation rooms]
• aldehyges: sterilize! (glutaraldehyde or cidex)
• Ethylene oxide: gas that sterilizes
• peroxygens: strong oxidizer, sterilizes

Question 22

What is the most used and useful disinfectant in everyday health care situations?

Answer 22

halogens: iodine and chlorine
- iodine: available as tincture (solvent in alcohol) or as iodaphor (combination of iodine and organic molecule which releases iodine slowly) –> betadine

• Chlorine: strong oxidizing agent (i.e. chlorox)
  (can be used by backpackers to decontaminate water and leaves no residual chlorine taste)

halogens can sterilize if appropriate amount of active chemical is used and prolonged time of exposure

Question 23

Which microorganisms does bacterial not kill? and which do they kill?

Answer 23

they cant kill endospores and non-enveloped viruses but they can kill bacteria and fungi

Question 24

what is the mechanism in which alcohol kills microoorganism?

Answer 24

protein denaturation and disruption of the lipid membranes

Question 25

what is alcohol not good for?

Answer 25

not good for treating wounds because they can cause a coagulation of proteins, creating an environment where the bacteria can grow inside the scab

Question 26

what IS alcohol good for?

Answer 26

degerming the skin

Question 27

what is the optimal conditions of ethanol for denaturation?

Answer 27

70% of ethanol (NOT 100%)

Question 28

what is isopropanol?

Answer 28

rubbing alcohol –> works better than ethanol –> and does not evaporate as fast

Question 29

Rank the microorganisms from most susceptible to chemical agents to least?

Answer 29

most:
enveloped viruses
gram + bacteria
naked viruses
fungi
gram negative bacteria
vegetative protozoa
cysts of vegetative protozoa
mycobacteria
endospores 
prions