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Unformatted text preview: Introduction: This lab was conducted to determine different types of bacteria within the mouth and on the body. By using the spread plate technique, the amount of bacteria present in the initial sample of saliva was counted and averaged within the class data. Many individual experiments were conducted within the lab to assess the different colonies present and their properties. The human body is covered with millions of microbes, inside and out. In the experiments today, microbial flora of the skin and oral cavities will be examined. Microbial flora are bacteria associated with the human body and the skin is covered with nearly 2 square meters of skin, containing about 10 12 bacteria. Most of these bacteria share a commensal relationship in which the bacteria benefit and the human is unharmed. I t is important to understand microbial flora I order to provide insight into possible infections that might occur as a direct result of an injury to different parts of the body. These microbes can also help understand the consequences of growth as a body sight where these organisms are normally absent. Under normal circumstances, these opportunistic microbes do not cause disease but if they are introduced to the blood stream or tissues disease can occur. Commensal microorganisms living on or in the skin can be either resident or transient. Resident bacteria normally grow on or in the skin and become fixed, while transient bacteria are only temporarily present and are usually unable to multiply. Most skin bacteria are found on superficial cells, dead cells, or associated with the oil and sweat glands. The skin is a non-specific first line of defense that is a strong barrier to microbial invasion. Few microorganisms can penetrate the skin due to thick, closely packed keratinocytes on the surface of the skin. In addition to these cells, there is sufficient shedding of the outer epithelial cells that remove bacteria adhering to the surface of the skin. Microbes are also unable to penetrate the skin due to the unfavorable slightly acidic ph environment and lack of moisture. The oil and sweat glands provide water and nutrients for microbes making it a favorable environment such as Staphylococcus epidermidis , aerobic corynebacteria, and gram- positive, anaerobic Propionibacterium acnes , which are most prevalent in the oil glands. Propionibacterium acnes are normally harmless but may t rigger an...
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- Spring '08