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Comparative Study Of Antibacterial Activity Of Two Selected Medicated Soap And One Local Black Soap On Staphylococcus Aureus From Wound Infection
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In order to study the properties of a
given organism, it is necessary to handle it in pure culture free of all
other types of organism by isolating a single cell colony from all
others and cultivated in such a manner that is collectively progeny also
remain isolated.
Since in the majority of cases, the organism to be
isolated is part of a mixed population, the isolation of a single
species from the environment is crucial. The isolation of single species
from a mixture of micro-organisms is called the pure culture technique.
Two methods are routinely used in the laboratory to obtain pure
cultures, each can be enhanced by isolation of selective media if
appropriate. They include:
(a)Pour Plate Method
In this method,
the mixed population of micro-organism is first diluted and a small
quantity is transferred to the bottom of a sterile petri-dish. Melted
agar is then poured into the petri-dish to cover the micro-organisms and
gently tilted to ensure uniform distribution of organism. Colonies will
develop on the surface as well as within the Agar.
(b)Streak Plate Method
In
the streak method, a small quantity of the mixed bacteria population in
a specimen is streaked directly on the surface of an already set agar
medium. The streaking is done with a wire loop. The procedure thins out
the microbial population on the surface of the Agar, and where an
organism has been deposited, a colony will develop after a suitable
incubation. From one of these colonies is streaked onto the surface of a
second plate and the colonies that develop there are also examined.
This subculture procedure ensures that only one kind of micro-organism
was present in the initially isolated colony.
1.4.1Identification of Contaminants (Micro-organism)
The
various metabolic activities of bacteria and their responses to
immediate environmental changes have been explored in the design of
special diagnostic and selective media.
Such media are used in public
health laboratories and hospitals for identifying organisms found in
samples believed to be contaminated by them and as an aid to their
diagnosis and treatment.
Micro-organisms have specific shapes and
structures that can be identified and characterized. The following are
some of the techniques used in the identification of micro-organism in
the laboratory.
(a)Examination of stained preparations: for example
Gram-staining procedure: This is one of the first important
identification procedures after isolation of colonies and enhances the
divison of the bacteria world to at least four (4) categories, namely:
i.Gram Positive colliii.Gram Positive Bacilli
iii.Gram Negative colliiv.Gram Negative Bacilli
(b)Examination of biochemical characteristics, for example:
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ABSRACT - [ Total Page(s): 1 ]Cosmetic(creams) need not be sterile,however they must not be unduly contaminated with micro-organism and should remain in a stable state throughout the shelf life of the product (or when be used by the consumer).the aim of this project was to determine the microbial load in selected creams and to identify the specific contaminants.For the determination of the number of contaminants, 1 mL of each cream was diluted to a factor of 104,1mL of this dilution was mixed with cool nutrient agar and macC ... Continue reading---
