Sterilization and disin.

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Submitted By Karim Nawaz
Submitted To Mam Laiba Zahid
Roll Number 70106901
Subject Introduction to Quality and Patient Safety
Department DHPT
Semester BS-OTT (SEM2)
Topic Sterilization and its Methods
Submitted Date 08/03/2021

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Sterilization
Sterilization is defined as a process of complete elimination or destruction of all forms of
microbial life (i.e., both vegetative and spore forms), which is carried out by various physical
and chemical methods. Technically, there is reduction ≥106
log colony forming units (CFU) of
the most resistant spores achieved at the half-time of a regular cycle.
Chemical sterilant
These are chemicals used for a longer duration (3–12 h) to destroy all forms of microbes, e.g.,
peracetic acid (PAA) (0.2%), glutaraldehyde (≥2.4%), ortho-phthalaldehyde (OPA) (0.55%), and
hydrogen peroxide (7.5%).
Disinfection
Disinfection is defined as a process of complete elimination of vegetative forms of
microorganisms except the bacterial spores from inanimate objects. Technically, there is
reduction of ≥103
log CFU of microorganisms by this method without spores.
High-level disinfectant (HLD)
Used for shorter duration and able to kill 106
log microorganisms except spores, e.g.,
glutaraldehyde (≥2.0%), OPA (0.55%), hydrogen peroxide (7.5%), hypochlorite (650–675 ppm),
and hypochlorous acid (400–450 ppm).

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Intermediate level disinfectant (ILD)
These disinfectants act against Mycobacterium tuberculosis and are mainly used for noncritical
items contaminated with blood/body fluids.
Low-level disinfectant (LLD)
LLDs are used to remove the vegetative form of bacteria, few fungi, and some enveloped viruses
from the noncritical items, e.g., 3% hydrogen peroxide, quaternary ammonium compound,
diluted glutaraldehyde, phenolics, etc.
Decontamination and cleaning
Decontamination is the process of removal of pathogenic microorganisms from objects so that
they are safe to handle. Cleaning is defined as removal of visible soil (e.g., organic and inorganic
materials) from the surfaces and objects. Technically, it achieves minimum reduction of ≥1 log
CFU of microorganisms.
Antisepsis
Antisepsis is a process of removal of germs from the skin. When it is related to the patient’s skin,
it means disinfection of living tissue or skin. When it is related to the health care worker, it
means reduction or removal of transient microbe from the skin.

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Germicide
It is the agent that destroys germs. It includes both antiseptics and disinfectants.
The type of microorganism is identified from the prefix (e.g., virucide, fungicide,
bactericide, sporicide, and tuberculocide).
Physical Methods
Heat
Most reliable process. There are two major methods of using heat in sterilization which are dry
heat and moist heat. The principle behind both of these methods is similar. Dry heat induces the
denaturation of protein, oxidative damage and toxic effect due to the high level of electrolytes.
Moreover, the dry heat can also damage the DNA of the microorganism. As a result, the
microorganism got killed. Moist Heat kills the microorganisms by denaturation and coagulation
of proteins. There are several factors that can influence the heat killing procedure.
Dry Heat
Red Heat
Inoculation loops, wires, forceps tips, needles are needed to be sterilized to inhibit microbial
contamination. These instruments are held in the flame of a Bunsen burner until they become red
hot.
Flaming
Glass slides, scalpels, and mouths of culture tubes or conical flasks are passed
through Bunsen flame without allowing them to become red hot.

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Auto Clave
The invention of the autoclave sterilizer is attributed to Charles Chamberland, in 1879. Around
that time, researchers started to understand the advantages of sterile surgery, and doctors needed
a more reliable sterilization method than open flaming. The autoclave’s benefits were soon
evident, and it became an essential part of every clinic and hospital.
An autoclave is used to sterilize surgical equipment, laboratory instruments, pharmaceutical
items, and other materials. It can sterilize solids, liquids, hollows, and instruments of
various shapes and sizes. Autoclaves vary in size, shape and functionality. A very basic
autoclave is similar to a pressure cooker; both use the power of steam to kill bacteria, spores and
germs resistant to boiling water and powerful detergents.
What is an Autoclave Used for?
An autoclave chamber sterilizes medical or laboratory instruments by heating them above boiling
point. Most clinics have tabletop autoclaves, similar in size to microwave ovens. Hospitals
use large autoclaves, also called horizontal autoclaves. They’re usually located in the the Central
Sterile Services Department CSSD) and can process numerous surgical instruments in a single
sterilization cycle, meeting the ongoing demand for sterile equipment in operating rooms and
emergency wards.

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Generating Steam and Steam Quality
Steam is the autoclave’s sterilization agent. In our Sterilization Methods series, we explained the
physics of steam and why it’s ideal for destroying microorganisms such as bacteria and spores.
Part 1 of this post will explain how steam is generated for autoclaving purposes. Part 2 in this
series will discuss the various types of autoclave steam supply and generation and when each is
used.

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