Week 13

 

Staphylococcus Aureus is the major reason for “human bacterial infections” throughout the world. This bacterium can cause everything from trivial skin infections to major infections that lead to death. The reason being is that it can obtain resistance to antibiotics like penicillin and methicillin (DeLeo, 2010; Deurenberg & Stobberingh, 2008).  This “pathogenic Gram-positive bacterium” lives closer to us than what we may think. It can be found in our nasal area and also our hands can be used as vectors to transfer the bacteria. Intact skin has a smaller chance of getting infected than wounded skin. It’s communicable through close contact and will last for months on any type of surface (Wertheima et al., 2005). In order to know which antibiotic to use to treat an infection, the bacteria causing the infection should be identified.

To identify the bacteria cultured from human skin, the methodology was slightly modified from how it was conducted in Aher, Roy, and Kumar’s 2012 study, “Molecular detection of virulence genes associated with pathogenicity of Gram positive isolates obtained from respiratory tract of apparently healthy as well as sick goats.” In that research, methods included obtaining nasal swabs, bacterial isolation,  incubation at 37° C, morphological identification based on Gram's staining, biochemical identification of Gram positive, DNA Extraction, Polymerase chain reaction (PCR) for amplification, identification of amplified genes based on fragments’ size. For more definite results, sequencing the DNA was also planned.

Before DNA can be sequenced, it needs to be isolated. The course of extracting DNA from its source by separating it from other cellular constituents is called DNA isolation (“DNA Isolation Methods,” 2005). To study DNA, enough of an amount of it should be available; otherwise, DNA should be copied to obtain the amount needed. The technique used for DNA replication is called “polymerase chain reaction (PCR)” (Maczulak, 2011). Composition of DNA of a species is specific to that species and different from the others. Distinctive sequences of nucleotides give DNA its unique characteristic that serves to identify an organism from the others in the same way that a person’s fingerprint does to identify a person from others (Maczulak, 2011; DNA, 2005). Fingerprinting DNA can reveal the identity of individuals and, therefore, is used for recognition of criminals, war and accident casualties, paternity, and classifying plants or animals in forensic science. Another purpose of isolating DNA is to diagnose a genetic disorder (“DNA Isolation Methods,” 2005).

Another way to identify bacteria is based on “antigen-antibody bonding”. These rapid tests are often used in doctors’ offices to rapidly identify bacteria like streptococcus.  In this method, a specific region of bacterial or viral DNA or RNA, called “target regions,” are being spotted. Special genes are being introduced to the infected body, which code for the existence of the target region. Diagnosis of a disease can be done a lot faster using this method, comparing to the old methods of only looking for symptoms (Hoyle, 2008).

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