Lab 4 - Kong Siao Thung

LAB 4: SOURCES OF CONTAMINATION AND INFECTION 

Name : Kong Siao Thung

Matrice No. : 111372

Introduction

Airborne microorganisms are usually carried on dust particles, although some may be carried directly by air currents (for example,fungal spores). 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 them are vital to our wellbeing, constitute our resident or normal microflora. Resident microorganisms are nourished by the chemicals and moisture excreted by the human body. In moist areas such as armpit, there may be one million bacteria per cm^3; on the drier skin of the forearm, there may be 10000 bacteria per cm^3.

Resident microorganisms are either nonpathogenic or are prevented from infecting the body by an array of mechanical and chemical defences. Some resident microbes are, however, 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 example, 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 other environments, they are poorly adapted to conditions on the skin and usually disappear within 24 hours of arrival.

Microorganisms in the upper respiratory tract are either normal residents or transients. As with the skin, the normal microflora are largely consists of nonpathogen or opportunistic pathogens.

Large numbers of transients enter the upper respiratory tract as we breathe or eat. They may also come from our own hands or or from improper sanitation during food preparation. Regardless of their origin, most transients are nonpathogenic and are quickly killed by various defences arrayed against them.

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

Results

1) Colonies in air :

2) Colonies of hands :

3) Colonies of ear:

4) Colonies of normal breathing :

5) Colonies of violent coughing :

Discussion

Microorganisms found in the air

The microorganisms which can be found in air are vegetative cells and spores of bacteria, fungi and algae, viruses and protozoan cysts. Microorganisms can be transferred into the air when human or animals sneeze, or by the wind picking up the light particles and blowing them where humans are. When a human sneezes, microorganisms leave the lungs at around 200 miles per hour. There are also microorganisms growing in the mucus in the respiratory tract enter the air with moisture particles that are sneezed out of the lungs.

Microorganisms found in the ear

Our ear is divided into few parts. The outer ear is home to a varied collection of bacteria, yeast and molds. The middle and inner ears are normally free microbes, but can become occupied and infected by persistent coughing, sneezing and nose-blowing. Ear wax is composed of dead cells and keratin with a small mixture of cerumen, sweat and oil. Coughing, sneezing and nose blowing open the Eustachian tube, allowing microbes to enter the ear. The most common bacteria are Staphylococcus epidermis, Turicellaotitidis, Alloiococousotitis, Pseudomonas aeruginosa, Corynebacterium, Staphylococcusaureus and Streptococcus saprophyticum. The most common fungal microbe known to reside in the ear is Candida albicans. This bacterial flora does not thrive under normal circumstances. Microbes are known to inhabit the middle ear are Streptococci, Haemophilus pneumonia, Moraxella catarrhalis, and less commonly Mycobacterium. These bacteria migrate through the nasophraynx and Eustachian tube to the middle ear.

Microorganisms found on hands

There will be certain amount of bacteria present on our hands. The bacteria are adapted to living on human skin and are harmless or symbiotic. They help to defend against harmful bacteria. There are millions of bacteria, fungi and viruses on our hands. Staphylococcus aures is the most common bacteria found in the nose and also on the hands. Staphylococcus aures forms a fairly large yellow colony on rich medium and it can grow at temperature range of 15 to 45 degree celcius and NaCl concentrations as high as 15%. Staphylococcus are grown in clusters because the cells divide successively in three perpendicular planes with the sister cells remaining attached to one another following each successive division. The exact point of attachment of sister cells may not be within the divisional plane and the cells may change position slightly while remaining attached. Therefore the result is formation of irregular cluster of cells.

Microorganisms found in normal breathing

Human’s nose and throat contain a lot of microorganisms. However, the lower respiratory structures, the larynx (voice box), trachea (windpipe), bronchi, bronchioles, and alveoli (the microscopic air sacs in the lungs)have built-in barriers. The narrowing of the tubes keeps some bugs out, and the numerous waving, hair-like cilia that fringe the cells lining the tract propel bugs up and out. Normal breathing is typically quiet without wheezes, coughing, bubbling sounds, or other noises. Breath odor is the scent of the air you breathe out of your mouth. Unpleasant, distinctive, or offensive breath odor is commonly called bad breath. Some disorders will produce specific, characteristic odors to the breath. Bad breath related to poor oral hygiene is most common and caused by release of sulphur compounds by bacteria in the mouth. One of the dangers of cigarette smoking is tobacco tar's destruction of the protective cilia, which provides a gateway  for bacteria from the nose and throat to the lungs. 

Microorganisms found in violent coughing

Frequent coughing usually indicates the presence of a disease. Many viruses and bacteria benefit evolutionarily by causing the host to cough, which helps to spread the disease to new hosts. Streptococcus mutans, causes dental caries (cavities), but only under certain conditions. Sticky foods, such as candy and raisins, enable the bugs to cling to teeth, where they produce acids that eat away at tooth enamel.  Most of the time, coughing is caused by a respiratory tract infection but can be triggered by choking, smoking, air pollution, asthma,gastroesophageal reflux disease, post-nasal drip, chronic bronchitis, lung tumors, heart failure and medications such as ACE inhibitors. A cough can be the result of arespiratory tract infection such as the common cold,pneumonia, pertussis, or tuberculosis. Infections in the breathing tubes can be caused by both bacteria and viruses, although the most common cause in children is a virus.

Conclusion

There are a lot of microorganisms presence in the air, on human hands and ears, in normal breathing and violent coughing such as bacteria, fungi and virus.

References

http://en.wikipedia.org/wiki/Infection
http://en.wikipedia.org/wiki/Contamination
http://en.wikipedia.org/wiki/Microorganism#Habitats_and_ecology
http://library.thinkquest.org/CR0212089/micr.htm
http://wiki.answers.com/Q/Do_we_have_bacteria_on_our_hands#ixzz1IFqPqcDp
http://en.wikipedia.org/wiki/Staphylococcus_aureus
http://www.suite101.com/content/normal-flora-and-opportunistic-pathogens-a93484
http://www.articlesbase.com/diseases-and-conditions-articles/types-and-prevention-of-bacteria-471084.html