Antisepsis and Sterilization

Question 1

What is germ theory?

Answer 1

microorganisms cause disease

Question 2

What are Koch’s postulates?

Answer 2

• microbes must be present in all disease cases
• microbe must be isolated from the infected host and grown in pure culture
• when a pure culture is introduced into a susceptible host, the disease must be reproduced
• microbes must be isolated from a purposely infected host.

Question 3

What is nosocomial infections?

Answer 3

Those infections whose onset and confirmation occurs greater than 48 hours after hospital admission.

“hospital acquired”

Question 4

Can healthcare associated infections be long term?

Answer 4

Yes, occuring within 6-12 months of systemic antibiotic treatment, long-term care facilities, central IV, urinary catheter, dialysis

Question 5

What are some reasons for high rates of hospital infections?

Answer 5

high prevalence of pathogens, compromised patients, efficient transmission from patient to patient by hospital personnel.

Question 6

What is the single most important method to limit transmission of nosocomial agents?

Answer 6

proper hand hygiene

Question 7

Define disinfectant

Answer 7

a physical or chemical agent used to inhibit or destroy microorganisms on inanimate objects.

Question 8

Define antiseptic

Answer 8

a physical or chemical agent used to inhibit or destroy microorganism on SKIN or TISSUE.

Question 9

An agent that inhibits bacterial growth is called

Answer 9

bacteriostatic

Question 10

An agent that destroys or inactivates bacteria is called

Answer 10

bactericidal

Question 11

What are some examples of chemical agents?

Answer 11

phenolics, alcohol, halogens, surfactants, aldehydes, oxidizing agents

Question 12

How do phenolics and alcohol work?

Answer 12

denature proteins and disrupt cell membrane

Question 13

How does halogen work?

Answer 13

iodine is an example. It works by iodinating or oxidizing bacterial proteins. Chlorine oxidize proteins too.

Question 14

What is more effective against bacteria, spores and viruses: halogen or phenolics/alcohol?

Answer 14

halogens, because phenolics and alcohol are ineffective against spores, non-enveloped viruses, and protozoans cysts.

Question 15

How does surfactant work?

Answer 15

contains hydrophobic and hydrophillic groups and perturb cell membrane

Question 16

Define sterilization

Answer 16

complete killing or removal of all living organisms from an item or area

Question 17

How is sterilization best accomplished?

Answer 17

physical methods (bacteria are killed exponentially over time)

Question 18

What are some examples of physical methods?

Answer 18

heat, cold, filtration, radiation

Question 19

How does heat work?

Answer 19

HIgh temperatures denature proteins, reduce integrity of cell membrane and denature DNA

Question 20

Moist or dry heat kills most rapidly?

Answer 20

moist heat because reactive water molecules denatures proteins by disrupting H bonds formed b/w amino acids.

Question 21

What is the most efficient way to sterilize ?

Answer 21

autoclave

Question 22

What does boiling do?

Answer 22

It does NOT sterilize but kills mostly everything except spores or cysts

Question 23

How does pasteurization work ?

Answer 23

It does not sterilize but involves heating then rapid cooling. No effects on spores

Question 24

How do filters work?

Answer 24

it removes live and dead bacteria from liquid. However, viruses can pass through.

Question 25

How do nonionizing radiation work?

Answer 25

UV rays is sterilizing because it excites e- and leads to formation of T-dimers in DNA. Typically used to disinfect air and surfaces in hospital

Question 26

Shorter or longer wavelenghts are more damaging?

Answer 26

shorter b/c it provides more energy and better cell penetration. it can damage DNA and produce free radicals, H2O2. Short waves are ionizing radiation, used in sterilization of surgical tools