Hospital Hygiene

STERILIZATION AND DISINFECTION

Definitions
Bacteriostatic

Agent: An agent that inhibits the growth of bacteria, but does not necessarily kill them. Bactericide:
An agent that kills bacteria. Most do not kill Endospores.
Sporicide:

An agent that kills spores.

Definition
STERILIZATION
The process of freeing an article from microorganisms including their spores.

By definition, it effects a reduction in the number of microorganisms (more than 99.9999% are killed).

Methods of Sterilisation
Microbial Control Methods

Physical Agents

Chemical Agents

Mechanical Remova Methods

Physical Agents

Heat

Radiation

Dry

Moist

Ionizing

Non Ionizing

Incineration

Pasteurization

X Ray, Cathode, Gamma

UV

Dry Oven

Boiling Water/Hot Water

Sterilization

Disinfection

Flaming

Autoclaving

DRY HEAT :Incineration
Temp: 879-980 oC This is an excellent method of destroying materials such as contaminated cloth, animal carcasses and pathological materials.

INCINERATION

DRY HEAT: Dry Oven
Sterilisation By Dry Heat:
• Kills

by oxidation effects

•The oven utilizes dry heat to sterilize articles • Operated between 50oC to 250/300oC.
•A holding period of 160oC for 1 hr is desirable.

• There is a thermostat controlling the temperature.
•Double walled insulation keeps the heat in and conserves energy,
Hot Air Oven

DRY HEAT: FLAMING
250-300 °C  Inoculation loop or Wire, the tip of Forceps and spatulas are held in a bunsen flame till they are red hot.


MOIST HEAT STERILIZATION
Kills microorganisms by coagulating their proteins. Types:  Temp below 100oC: “Pasteurisation”,
 

Temperature at 100oC: Boiling. Temperature above 100oC : Autoclave.

Pasteurisation


Process of killing of pathogens in the milk but does not sterilize it .



Milk is heated at 63oC for 30 mins. (HOLDER METHOD)

At 72oC for 15-20 Sec. Rapid cooling to 13oC (FLASH PROCESS)
