Micro: Antisepsis and Sterilization

Question 1

Who is the Dr. that determined that Docs should wash hands before going from one labor room to the next?

Answer 1

Ignaz “the vag magnet” Semmelweis

Question 2

_______ infections are those whose onset and confirmation occur greater than 48 hrs after hospital admission.

Answer 2

Nosocomial infections (hosp. acquired)

Question 3

Healthcare-associated infections differ from nosocomial infections in that they are the result of _______ , not simply those that are found within 48 hrs of admission (i.e. those contracted simply from the environment of a hospital)

Answer 3

Treatments or long-term residence

Question 4

The single most important method to limit transmission of nosocomial agents is __________________.

Answer 4

proper hand hygiene

Question 5

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

Answer 5

Disinfectant

Question 6

An ________ is a physical or chemical agent used to inhibit or destroy microorganisms on skin or other tissue.

Answer 6

antiseptic

Question 7

Do Disinfectants and antiseptics eliminate potential pathogens?

Answer 7

No, they reduce them.

Question 8

________ agents inhibit bacterial growth.

Answer 8

Bacteriostatic

Question 9

________ agents destroy or inactivate bacteria.

Answer 9

Bactericidal

Question 10

How do phenolics and alcohols kill bacteria? Are they effective against spores, protozoan cysts and certain non-enveloped viruses?

Answer 10

Denature proteins and disrupt cell membranes. Not effective against spores, protozoan cysts and certain non-enveloped viruses.

Question 11

Is isopropyl alcohol’s action fast or slow?

Answer 11

Slow

Question 12

How does chlorhexidine kill bacteria?

Answer 12

alters membrane permeability (topical phenolic)

Question 13

Is pure alcohol an effective antimicrobial?

Answer 13

No, most alcohol solutions are diluted with water to 70-95% strength.

Question 14

How does iodine, a halogen, work as an antiseptic?

Answer 14

Works by iodinating or oxidizing bacterial proteins.

Question 15

How does chlorine, a halogen, work as an antimicrobial?

Answer 15

Oxidizes bacterial proteins

Question 16

________ are effective against bacteria, spores and most viruses and are therefore more effective than phenolics or alcohols.

Answer 16

Halogens

Question 17

How do surfactants kill bacteria?

Answer 17

perturb bacterial cell membranes leading to cell death due to hydrophobic and hydrophilic groups.

Question 18

Glutaraldehyde is an alkylating agent used to disinfect equipment. How does it work?

Answer 18

First polymerizes and then binds to proteins in the outer membrane of gram neg. bacteria and amino acids found in the peptidoglycan cell wall of gram pos. bacteria. The subsequent alkylation inactivates the proteins, killing the cells.

Question 19

This is an alkylating, gaseous agent used to treat heat-labile equipment. It thoroughly kills (sterilizes) all contaminants.

Answer 19

Ethylene oxide gas

Question 20

Several chemical agents are capable of oxidation, but ______ ______ acts solely in this manner.

Answer 20

Hydrogen Peroxide

Question 21

How does hydrogen peroxide kill bacteria?

Answer 21

It attacks the lipid membrane and other cellular components, but is less effective against spores and cat-positive bacteria.

Question 22

What is the only chemical agent capable of completely eliminating all contamination (sterilization)?

Answer 22

Ethylene oxide gas

Question 23

________ is the complete killing or removal of all living organisms from an item or area.

Answer 23

Sterilization

Question 24

List the 4 physical methods of bacterial control.

Answer 24

heat, cold, filtration, radiation

Question 25

What kills more rapidly, moist heat or dry heat and why?

Answer 25

Moist heat, reactive water molecules denature protein by disrupting hydrogen bonds formed between AAs.

Question 26

Autoclaving at _____ PSI and ______ Celsius for ____ minutes will kill all bacteria, fingi and viruses.

Answer 26

15 PSI, 121 Celsius, 15 minutes

Question 27

Is the 15 PSI, 121 Celsius, 15 minutes rule for autoclaving adequate for spores and cysts?

Answer 27

No, time is extended.

Question 28

Minimum temp and time standards for dry heat sterilization are:

Answer 28

160 Celsius for 2 hrs. This is because dry air does not conduct heat as well as moist air.

Question 29

Does boiling objects sterilize them?

Answer 29

No. But does kill most non spores/cysts within 10 mins.

Question 30

Describe pasteurization. Does it sterilize?

Answer 30

Heat liquid to 55-75 Celsius for 30 mins, then rapidly cool. Does not sterilize, bacterial load reduced by 90%.

Question 31

Does freezing sterilize?

Answer 31

No.

Question 32

Cellulose membrane filters, with pore sizes as small as ____ microns (um) are able to remove live and dead bacteria from liquids.

Answer 32

0.2 um

Question 33

Do viruses pass through a 0.2 um filter?

Answer 33

Yes

Question 34

________ ________ such as UV radiation is sterilizing because it ______ ________ and leads to the formation of new covalent bonds, such as thymine-thymine dimers in DNA.

Answer 34

Nonionizing radiation; excites electrons

Question 35

Due to this property of nonionizing radiation, it has poor penetration properties, thereby limiting its usefulness.

Answer 35

Long wavelength

Question 36

Nonionizing radiation is typically used to disinfect ______ and _______ in hospitals.

Answer 36

air, surfaces

Question 37

What properties of gamma (ionizing) radiation make it better for kill bacteria embedded within tissues/structures?

Answer 37

Shorter wavelengths

Question 38

How does gamma radiation kill bacteria?

Answer 38

Transmitted energy damages DNA but also produces free radicals and creates hydrogen peroxide from cytoplasmic water.