STERILISATION

TOPICS

Introduction -Definition -History

-Terminology Classification of sterilizing

agents

STERILIZATION & DISINFECTION

Sterilization is defined as “the process by which an article , surface or medium is freed of all living microorganisms either in the vegetative or spore state.”

Disinfection means “the destruction or removal of all pathogenic micro organisms capable of giving rise to infection but not necessarily resistant spores.”

WHY STERILISATION???

Micro organisms are ubiquitous. To prevent contamination by

extraneous organisms. In surgery, to maintain asepsis. In food and drug manufacture to

ensure safety.

HISTORY Oliver Wendal Holmes(1843) and Ignaz

Semmelweis(1846) concluded that puerperal sepsis was transmitted by contaminated hands of Obstetricians, nurses, medical students.

Can be prevented by washing hands

in aseptic solution.

LOUIS PASTEUR(1822-1895) – Father of modern Microbiology.

Proposed “GERM THEORY” In the course of these studies,

he introduced techniques of sterilization and developed the steam sterilizer, hot air oven

and autoclave. Pasteurization.

JOSEPH LISTER – Father of Antiseptic Surgery.

In 1866, Lister suggested antiseptic

surgery which involved the use of “CARBOLIC ACID”.

Pronounced drop in mortality and morbidity observed. Marked the Beginning of Modern aseptic conditions from the era of Laudable pus.

Carbolic acid, phenol

JOHN TYNDAL (19th century) –Tyndallisation (Intermittent

sterilization). Student of Pasteur. Tyndallisation essentially consists of

boiling the substance at 1000C for 15 minutes for three days in a row.

Used for media containing sugars and gelatin.

It is generally effective, but its reliability is not considered 100% certified.

TERMINOLOGYTERM DEFINITION

Antiseptics Substances which either kill micro organisms of inhibit their growth

Disinfectants Compounds that kill micro organisms( except bacterial endospores)

Asepsis Technique that is employed in preventing infections from gaining access to an infected tissue.

Cleaning Cleaning is a soil removing process that removes many micro organisms . It a necessary prerequisite to sterilization & disinfection.

Sterilant Chemical agents that destroy all micro organisms including spores.

Germicide Chemical or physical agent that destroys most organisms but not endospores, used on skin and inanimate objects.

Sporocide Generally a chemical agent that destroys both bacterial & fungal spores

Fungicide Chemical substances that destroy fungi

Virucide Chemical agents that destroy viruses

Bactriostat Chemical agents that inhibit bacterial growth

Sanitizer An agent, usually a detergent that reduces the no. of bacteria to a safe level

WHICH METHOD OF STERILISATION??

The method of sterilization to be employed depends on :

The purpose for which it is carried out.

The material which has to be sterilized.

Nature of micro organisms to be destroyed.

CLASSIFICATION OF STERILIZING AGENTS

THANK YOU….