LAB4 : SOURCES OF CONTAMINATION AND INFECTION

Introduction

Contamination is the unwanted pollution of something by another substance, for example leaking of petroleum storage tanks in the sea. There are three main causes of contamination: physical, chemical and microbiological hazards. Many harmful microorganisms can be transmitted by a host and in air currents with dust particles. When a victim or a host was infected by a diesease, he or she can easily spread the infectious microorganism into air by coughing, sneezing or even breathing. Thus, it is very difficult to be avoided to come into contact with these microorganisms.

Every human contacts with two types of microorganisms, which is resident and transient microorganisms. Resident microorganisms are life-long members of the body's normal microbial community, but are not found everywhere. They are normally colonised on the surface of the skin, mucous membranes, digestive tract, upper respiratory system and distal portion of the urogenital system throughout life. They are usually commensal that feeds on excreted cellular wastes and dead cells or mutualistic by provide vitamin K and Vitamin B.

Transient microorganisms are Normal Microbiota remain in the body for only hours to months before disappearing. They cannot persist in the body because pf the competition from resident microorganisms, elimination by the body's defense cells, and chemical or physical changes in the body that expel them. These microorganisms contact with human in daily life such as breathing, eating and touching. Resident and transient microbes cause the host no harm to human under normal circumstance. They become opportunistic pathogens only

when immune suppression of the host, reduction in microbial antagonism, and introduction of normal microbiota into an unusual site in the body.

Objective

To determine the microorganisms in the air and from healthy humans

Materials and Reagents

Molten nutrient agar

Sterile water

Sterile petri dishes

Sterile clinical swab

Pipette and tips

Bunsen burner

Procedure

(Refer to lab manual)

Results

1. Air

	Commercial molten agar	Self-made molten agar
Elevation	raised	raised
Margin	entire	Entire,undulate
Texture	moist	moist
Size	Small,large	small
Form	circular	Circular,irregular
Surface	Smooth,rough	smooth
Colour	Pale yellow	white

2. Normal breathing

	Commercial molten agar	Self-made molten agar
Elevation	Flat,raised	raised
Margin	entire	entire
Texture	moist	moist
Size	small	small
Form	circular	circular
Surface	Shiny and smooth	smooth
Colour	yellow	white

3. violent couging

	Commercial molten agar	Self-made molten agar
Elevation	Raised,convex	raised
Margin	Entire, undulate	entire
Texture	dry	dry
Size	small	small
Form	Circular,irregular	circular
Surface	Shiny, smooth	Shiny, smooth
Colour	yellow	yellow

4. Ear

	Commercial molten agar	Self-made molten agar
Elevation	raised	raised
Margin	entire	entire
Texture	moist	moist
Size	small	small
Form	Circular,irregular	Circular,irregular
Surface	Shiny and smooth	Shiny and smooth
Colour	white	white

5. Hand

	Commercial molten agar	Self-made molten agar
Elevation	raised	raised
Margin	Entire,undulate	Entire,undulate
Texture	moist	moist
Size	Small,large	Small,large
Form	Circular,irregular, filamentous	Circular,rhizoid, irregular
Surface	Shiny&smooth, rough&dull	Smooth, rough&dull
Colour	Yellow,white	white

Discussion

Bacterial populations grow extremely fast when under the favourable environmental condition and adequate nutrients condition. Different types of bacteria will produce colonies that have different appearances. Colony morphology is a way scientists identify bacteria according to their size, surface, texture, colour, form, elevation and margin.

For the contamination by air, there were little or fewest colonies on the both media compared to the other media that we have prepared. It is due to the low concentration of contaminants in the air of laboratory. The common bacteria found in the air are Bacillus, Staphylococci and Clostridium.

For contamination by hand, there were many colonies formed. This is because our hand carries thousands of microbes as we came in contact with many contaminated things throughout our living.

For ear contaminations, the sample was taken by an ear pick. Before it came in contact with our ear, the ear pick was dipped into distilled water .The sample is taken from the outer part of our ear and is spread on the culture by using streaking plate technique. As we could see from the result, the colonies were formed along the line that we streaked. Some common bacteria that lives in our outer part of the ear are Staphylococcus,Turicillotitidis and Alloiococcusotitis. For the internal part of the ear, most of the microbes were trapped by ceremonious gland.

For violent coughing, we could observe only few colonies on both agars. This is because most of the bacteria and microbes from nasal passage being trapped by the mucus and expelled to the outer environment as we cough.

For normal breathing, there are a few spots of colonies formed. Most of the bacteria from are non-pathogenic but some of them may cause illness. From normal breathing of a healthy person, the bacteria that might present are Staphyloccocus, Epedermis ,Corynebacterius and Micrococcus Luteus.

Conclusion

From the experiment, we found out that there are not significant differences between the colonies formed in commercial agar and self-made agar. Bacteria can grow well as long as the conditions are favourable. From the results observed, we also can concluded that the organs exposed to the outer environment, like ears and hands will contain more bacteria. At the end, we able to identify the bacteria according to the characteristics of colony morphology.

Reference

https://wikis.engrade.com/a105science2012/agarplating

http://labreport102.blogspot.my/2014/12/lab-report-4.html

http://ibg102.blogspot.my/2014/12/lab-4-sources-of-contamination-and.html