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Question 1

Disinfection and disinfectant

Answer 1

The destruction of pathogenic

Usually involves the removal of vegetative or non-endospore forming pathogens

Corrosive chemicals that are destructive to skin and mucous membrane

They are used where sterilization is not practicable

Question 2

Antiseptics

Answer 2

: Chemical agents (mild agents applied to body surfaces such as the skin without harming it)

Question 3

Actions of disinfectants

Answer 3

–Dissolve lipids from cell membrane: e.g. Detergents, lipid solvents
–Damage proteins or nucleic acids: e.g. Denaturants, oxidants, alkylating agents, sulfahydry reagents

Question 4

Actions of disinfectants depends on:-

Answer 4

•Concentration & type: disinfectants have bactericidal action at high, but bacteriostatic at low concentrations.
•Temperature
•Contact Time: duration of exposure to disinfectant
• pH - Anionic compounds – more active at low pH,
- Cationic compounds – more active at high pH

Question 5

Classification of disinfectants

Answer 5

•High level disinfectants.
•Intermediate level disinfectants.
•Low level disinfectants.

Question 6

HLD examples

Answer 6

1. Chlorine dioxide - Fast acting, very effective against HBV, HCV & HIV/AIDS, inexpensive, readily available.
2. Formaldehyde (8%) – inexpensive, readily available, an effective HLD but, the vapors are very irritating and is a potential carcinogen.
3. H2O2 (6%) - solution is less expensive
4. Glutaraldehyde (2%) - less irritating than formaldehydes
   •It has excellent biocidal activity, is active in the presence of organic matter & is non-corrosive to metals, rubbers

•Other: Peracetic acid (variable)

Question 7

ILDs plus example

Answer 7

Kill fungal spores, protozoan cysts, pathogenic bacteria
such as M. tuberculosis, vegetative bacteria & most viruses

Not for spore forming bacteria

•Phenol compounds
●Alcohol, 70%
●Iodophore compounds

Question 8

LLD

Answer 8

Kills most vegetative bacteria (except mycobacteria), some fungi, protozoa & only enveloped viruses

Soap

Question 9

Highest to least resistant

Question 10

Medical devices, equipment, surgical materials are divided into 3 general categories based on the potential risk of infection involved in their use:

Answer 10

Critical items -Should be sterilized or by h2o2 and Eto gas

Semi critical items- Devices that contact mucous membranes or non-intact skin but not penetrate soft tissue/body surfaces.
HLD

Non-critical Items -Non-critical items are those devices that touch only intact skin but not mucous membranes
By LLD or ILD

Question 11

Selected Disinfectants & Antiseptics

Answer 11

• phenols . Standard
  Chemical derivatives-dettol
• quaternary ammonium cpds . Quats
• halogens
• alkylating agents

Question 12

Advantage of phenols

Answer 12

Stable
Persist for a longer time
Remain active in the presence of organic cpds

Question 13

Quats

Answer 13

Cationic detergents
Inactivated by organic matter
Effective against gram positive
Not for gram negative
Eg
Chlorohexidon

Question 14

Halogens example

Answer 14

Chlorine
Iodine
Potassium permanganate