LAB 4: SOURCES OF CONTAMINATION AND INFECTION

Name : See Yen Shan
Matrix number : 111415

Introduction

Air borne microorganisms are usually carried on dust particles, although some (fungal spores, for example) can be carried directly by air currents. It is important for microbiologist to be aware of the potential for contamination by airborne microorganisms. Carefully observation of simple precautions dramatically reduces the risks of contamination.

      

       Every human is colonized by billions of microorganisms. These microorganisms, some of ehich are vital to our wellbeing, constitute our resident or normal microflora. Resident microorganisms  are nourished by the chemicals and moisture excreted by the human bod. In moist areas such as the armpit, there may be one million bacteria per cm3 ; on the drier skin of the forearm, there may be 10000 bacteria per cm3 ! ! !

  

      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 largely consists of non pathogens or opportunistic pathogens.

     Large numbers of transients enter upper respiratory tract as we breathe or eat. They may also come from our own hands 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.

Results

Colonies from air

Colonies from human's breathes

Breath colonies sample 1

Breath colonies sample 2

Colonies from human's coughs

Coughs colonies sample 1

Coughs colonies sample 2

Colonies from human's hands

Hands colonies sample 1

Hands colonies sample 2

Colonies from human's ears

Ears' colonies sample 1

Ears' colonies sample 2

Discussions

Living microorganisms in air

The atmosphere is not a very welcoming environment for many microorganisms. The joint effects of desiccation and sunlight cause many microbial cells to die rapidly when suspended in air. This is especially true of Gram-negative bacteria, including food borne pathogens like E. coli and Salmonella. Nevertheless, some Gram-positive bacteria and fungal spores can survive for long periods in the atmosphere and can be widely dispersed by air currents. The typical microflora of the air is usually made up of pigmented Gram-positive bacteria and bacterial and fungal spores, which are resistant to the drying effects of the air and to radiation. Unfortunately, it can include some pathogenic bacteria, such as Staphylococcus aureus and Bacillus cereus, and common food spoilage fungi, notably species of Penicillium and Aspergillus. 

Living microorganisms in human's breathes

Our mouth contains a lot of pathogenic and non-pathogenic microorganisms. The pathogenic bacteria will cause some microbial diseases of the respiratory system which may occur in the upper or lower regions. Some examples of these non-pathogenic bacteria are Streptococcus, Neisseria, Haemophilus, and Micrococcus. Whereas the pathogenic bacteria might cause strep throat, scarlet fever, diptheria. The pathogenic bacteria are Corynebacterium diphtheriae, Streptococcus pyogenes,Staphylococcus aureus and Streptococcus pneumoniae.


Living microorganisms in human's coughs


A cough is a sudden and often repetitively occurring reflex which helps to clear the large breathing passages from secretions, irritants, foreign particles and microbes. Actually the microbes during breathing and coughing are quite similar because there are originated from the same place, mouth and nose cavity in human beings.


Living microorganisms on humans' hands

The hands and fingernails are often affected by fungal and yeast infections. Some of the species are Cladosporium, Scopulariopsis, Aspergillus, Acremonium, Epidermophyton, and Trichophyton. There are also some bacteria that exist on our hands. These are the few common examples, Serratia, Aeromonas, Klebsiella, Pseudomonas, Staphylococcus, Acinetobacter and Enterobacter.

Living microorganisms in humans' ears


The bacterial pathogens at the top of the list are Pseudomonas aeruginosa and Staphylococcus aureus, followed by a great number of other gram-positive and gram-negative species.^[9] Candida albicans and Aspergillus species are the most common fungal pathogens responsible for the infections of ear. Otitis media is infection of the middle ear accompanied by earache. 


Conclusions


Fromincrease in a fast rate  the experiment, we can conclude that no matter is inside or outside of the human body or in the air, it contains a lot of pathogenic or non-pathogenic bacteria as well as fungi and yeast.Our human body   is just like a big nutrient media for those microbes. These microbes can survive and if the temperature and pH of the environment is favored.





References




http://www.scientificpsychic.com/health/hygiene.html
http://en.wikipedia.org/wiki/Otitis_externa
http://www.cliffsnotes.com/study_guide/Bacterial-Diseases-of-the-Respiratory-System.topicArticleId-8524,articleId-8496.html
http://microbewiki.kenyon.edu/index.php/Human_Hands_and_Fingernails

http://www.foodsafetywatch.com/public/1057.cfm