Control

Question 1

History

Answer 1

Pasteur> microorganisms can live on nonliving and destroyed by heat
Lister> chloride of lime for aseptic surgeries

Question 2

Antisepsis

Answer 2

Destruction of vegetative bacteria on living tissue

Question 3

Degerming

Answer 3

Removal from limited area

Question 4

Sanitisation

Answer 4

Lowering microbial count on food handling equipment to minimise transmisssion

Question 5

Why control

Answer 5

Quality control
Food preservation
Prevent disease

Question 6

Factors

Answer 6

No. Of microbes
Environmental factors
Time of exposure
Microbial characteristics

Question 7

How affect

Answer 7

Alter membrane permeability
Damage to proteins(hydrogen and disulfide bonds )
Damage to nucleotides(no replication/ metabolic functions)

Question 8

Physical

Answer 8

Temperature (high/ low)
Desiccation
Osmotic pressure
Filtration
Radiation

Question 9

High heat

Answer 9

Dry»flame/oven
Moist»autoclave/boiling/pasteurization

Question 10

Low heat

Answer 10

Refrigerator except listeria
Freezing> flash/slow

Question 11

Chemical control rules

Answer 11

High stability
Non toxic
Non corrosive
Broad spectrum
Fast acting
For water and lipids
Environmentally friendly

Question 12

Evaluating efficiency

Answer 12

Dilution tests>culture+ disinfectant then agar
Disk diffusion>disk soaked with disinfectant on agar previously inoculated.

Question 13

The agents

Answer 13

Phenols and phenolics
Halogens
Alcohols
Heavy metals
Aldehydes
Gaseous sterilisers
Oxidising agents

Question 14

Why phenol no longer used

Answer 14

Irritates skin
Bad odour

Question 15

Examples of phenolics
Mechanism

Answer 15

Biphenol(against staphylococcus in infants) (Phisohex)
cresols(floor cleaning)(lysol)
Disrupt cell membrane

Question 16

Halogens are…used for…

Answer 16

Iodine(betadine ) skin and wound all even endospores
Chlorine gas>hypochlorous acid
Liquid>calcium hypochlorite(water drink)
Sodium hypochlorite/clorox for swimming pools and dialysis and bleach

Question 17

Alcohols

Answer 17

Isopropanol better than ethanol but more expensive and poisonous

Question 18

Why 70% ethanol
Why not for open wounds

Answer 18

As denaturation need water
Forma coagulation under which bacteria grow

Question 19

Heavy metals combine with….
Are…

Answer 19

Sulfhydryl groups
Silver nitrate
Mercury chloride (toxic)
Copper sulfate (algicide )
Zinc chloride (mouthwash)

Question 20

Aldehydes work by…
Are..

Answer 20

Covalent cross links = protein inactivation
Formaldehyde> formalin for tissue preservation inactivated bacteria 37%
Glutaraldehyde > cidex steriliser for endoscopes and respiratory therapy

Question 21

Gaseous depend on…are..

Answer 21

Alkylation replacing H with alkyl group
Cross linking nucleic acids and proteins
Ethylene oxide> needs time , explosive so mixed with CO2
Chlorine dioxide>endospores of anthrax

Question 22

Oxidising agents

Answer 22

Hydrogen peroxide> sporicidal, inanimate
Not for open wounds as it breaks down to H2O and O2
Ozone> highly reactive, O2 through hugh voltage, disinfect water, neutralise taste