Matric's card no.: 111431
Lab 4 : Sources of contamination and
infection
Introduction
Contamination is the presence of a minor and unwanted
constituent (contaminant) in material, physical body, natural environment, at
workplace and so on. In biological sciences, accidental introduction of “foreign”
material (contamination) can seriously distort the results of experiments where
small samples are used. In cases where the contaminant is a living microorganism,
it can often multiply and take over the experiment, especially cultures and
render them useless.
An infection is the invasion of body tissues by disease-causing microorganisms, their multiplication and the reaction of body
tissues to these microorganisms and the toxins that
they produce. Infections are
caused by microorganisms such as viruses, prions, bacteria, and viroids, though larger
organisms like macroparasites and fungi can
also infect.
Airborne microorganisms are usually carried
on dust particles, although some (fungal spores, for example) may be carried
directly by air currents. It is important for microbiologists to be aware of
the potential for contamination by airborne microorganisms. Carefully observation
of simple precautions dramatically reduces the risk of contamination of the
cultures.
Every human is colonized by billions of
microorganisms. These microorganisms, some of which are vital to our wellbeing,
constitute our resident or normal microflora. Resident microorganisms are
nourished by the chemicals and moisture excreted by human body. In moist areas
such as the armpit, there may be one million bacteria per centimeter cube; on the
drier skin of the forearm, there may be 10000 bacteria per centimeter cube.
Resident microorganisms are either
nonpathogenic or are prevented from infecting the body by an array of
mechanical and chemical defences. Some resident microbes are, hower ,
opportunistic pathogens which may cause infection if the body’s defences are
breached. For example, if the skin is broken.
Transient microorganisms are picked up from
our environment. For instance,from faecal contact or from soil and usually fail
to become permanent skin residents. One of the most important reasons for
failure to gain permanence is that the established residents are better able to
compete for nutrients. Since transients generally originate in the other
environments, they are poorly adapted to conditions on the skin and usually
disappear within 24 hours of arrival.
Objective
To determine the
microorganisms in the air and from healthy humans.
Results:
1.) Colonies on ear
2.) Colonies in air
3.) Colonies from violent coughing
4.) Colonies in normal breathing
5.) Colonies on hands
Discussions:
1.) In this experiment, there are some precaution steps to be
taken:
#Spray some Lysol
solution on the table and rub it with a sponge before the experiment is
conducted.
#The sterile Petri dishes must be opened near the Bunsen
burner to avoid contamination.
# The Petri dishes containing culture medium agar and the hand-washed
water should be rotated lightly to make sure that the contents mixed together.
2.) Atmosphere contains all major groups of microbes ranging from algae to the viruses. In addition to gases, dust particles and water vapour, air also contains microorganisms. There are vegetative cells and spores of bacteria, fungi and algae, viruses and protozoan cysts. Since air is often exposed to sunlight, it has a higher temperature and less moisture. So, most of these microbial forms will die.
3.) Although bacteria consist of only one single cell, they're an amazingly complex group of living creatures. They can live in extreme temperatures, ranging from above the boiling point to low temperatures that would freeze human blood. Bacteria "eat" everything from sugar and starch to sunlight, sulfur and iron. There's even a species of bacteria" Deinococcus radiodurans" that can withstand blasts of radiation 1,000 times greater than would kill a human being. The entire ecosystem depends heavily upon the activity of bacteria. In their various forms, they're crucial for recycling organic matter such as leaves that fall off trees. Others digest some food within the human body that would otherwise be difficult to break down. Most bacteria fall into one of three groups, namely aerobic bacteria, anaerobic bacteria and facultative anaerobes. The most common bacteria in the air are E.coli , S.marcesens, S.aureus.
3.) Fungi are neither animals nor plants - in fact, they command one of the "Five Kingdoms of Life" all to themselves. There are over 100,000 species of fungi, but only about 400 cause diseases relevant to man, animals, or plants. Essentially, Fungi are plant-like organisms that lack chlorophyll. Without chlorophyll, which transforms light into energy, fungi must absorb food from others. Since they don't use light to make food, fungi can live in damp and dark places. Many strains of fungi are extremely useful. The job of Fungi is to "eat" things when they are dead - a kind of natural recycling system. Fungi find nutrients within our rubbish -they eat the waste and turn it into soil. There are also "good" fungi such as the mushrooms we eat, and the yeast we use to make both bread and beer. Bad fungus is just good fungus trying to do its job far too early - in other words, trying to eat before their food is actually dead. This includes the nutrients from the tissue of human beings (as in tinea or ringworm) and inside the lung and nasal passages (which causes diseases such as sinusitis).
4.) Mould
is the common name for fungi that grow in a filamentous (thread-like) fashion
and reproduce by means of spores; all moulds are fungi, but not all fungi are
considered "moulds". There are over 20,000 known species of moulds. The
filaments of mould are known as hyphae. At the tips are rounded, blob-like
forms called conidia or spores. These round fungal forms are relatively
metabolically inactive - all they're doing is trying to find a nice, warm,
moist place to live and multiply. Moulds reproduce by making spores. Spores are
microscopic; they vary in shape and size (2-100 micrometers - a micrometer is
one millionth of a metre). The spores allow the organism to survive during
periods where the conditions aren't ideal for growth (for example, some species
don't like dry, cool environments). Spores travel in several ways in search of
a place to live - passively (by wind, for example), when disturbed (by a
person), or when actively discharged by the mould (usually under moist
conditions or high humidity). Mould spores waft through the indoor and outdoor
air continually. When mould spores land on a damp spot indoors, they begin
eating whatever they are growing on. Moulds can grow on virtually any organic
substance, such as oil, dust, compact discs (CD's), skin cells and dirt providing
moisture and oxygen are present.
5.)Microcoocus is a
Gram-positive, aerobic bacterium which is a member of the Micrococcaceae
family. Micrococcus cells can be observed under the microscope as spherical
cells forming pairs or clusters. If cultured in broth or on nutrient agar, the colonies
may be red or yellow when observed unstained. Although these bacteria are a common
human skin contaminant, they are relatively harmless to humans because they
maintain a saprophytic lifestyle. They can also be found in freshwater environments
or in soil. Three common species of Micrococcus are M. luteus, M.roseus,
and M. varians.
7.) Bordetella
organisms
are small, Gram-negative coccobacilli which are strict aerobes. The three
species of this genus vary in motility and certain biochemical characteristics.
The most important species in this genus is B. pertussis, the organism which
causes whooping cough. This highly contagious bacterium makes its way into 53
respiratory tract via inhalation and subsequently binds to and destroys the
ciliated epithelial cells of the trachea and bronchi. It does this through the
use of several toxins: Pertussis toxin, Tracheal cytotoxin, Hemoagglutinin.
Conclusion
In conclusion, there are various microorganisms in the air and human's bodies. From this experiment, i found that there are various microorganisms in air. From the morphology of the colonies, i concluded that the culture might contaminated with the fungus and bacteria as they exposure to the air.
References
