There are significant normal microbiota of human beings which consists of a few protists and eukaryotic fungi, but bacteria are the most common known and most numerous microbial components of the normal flora. This normal microbiota can helps us widely by competing with pathogens such as Clostridiumbotulium, by providing substantial vitamins or by also eliminating toxins, or they can also harm us by promoting or by being the cause neither help nor harm.
The following is a list of the main sites of which normal microbiota is normally found in the human body:
The skin, for instance the moist areas, such as the groin and between the toes
The respiratory tract, particularly the nose.
The digestive tract (organs of the gastrointestinal tract) like for example the mouth, the terminal ileum and the colon.
In this study, the experiment was carried out by using the Kirby-Bauer Antibiotic Disk-diffusion method to test the sensitivity of the bacteria isolated from the healthy individuals with at least four different antibiotics. The antibiotics used were; Ampicillin, Oxacillin, Erythromycin and Levoflavin.
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The test was rigorously standardized since the zone of inhibition is also dependent on the inoculums size, medium composition, temperature of incubation, excess moisture and thickness of agar. If these conditions are uniform, reproducible tests can be obtained and the zone of exhibition diameter is only a function of the susceptibility of the test organism.
The zone of inhibition can be correlated with susceptibility as measured by dilution method. Further correlations using zone diameter the designation of an organism as "susceptibility", "intermediate", or "resistance" to concentrations of an antibiotic which can be attained in the blood or other body fluids of patients requiring chemotherapy.
The body a healthy individual normally contains approximately 20 to 25% of streptococcus living in their bodies and it is associated with recurrent throat infections and has been a major cause of morbidity and mortality in streptococcus pneumoniaepatients as most patient carry the microorganism in their mouths.
It was observed that discrete bacterial colonies were grown on the agar and was not a growth that spread all over the petri dish this was for growth of microbes that were swabbed from the throat. The agar of the throat swab changed colour from red to yellow and pink which shows that the bacteria were fermenting .
In the streak plate it was observed that there were more dense colonies formed on sector 1 and 2 and a fewer colonies found on sector 3, 4 and 5. This was because when the inoculating loop was flamed some bacteria were killed and also because the agar was more thick on the side of sector 1,2 and 3. The microbes were circular in isolated, cream in colour and the bacterias produced "off" odours.
In microscopy the results obtained were gram-positive streptococci which were blue in colour as observed under the microscope under oil immersion . The agar that was used was MSAwhich is a selective media, which means it only allows certain growth of desired microorganism and suppresses the growth of unwanted bacteria . So mannitol salt agar specifically promotes the growth of staphlylococci  but as viewed under the microscope gram-positive streptococcus bacteria which can be due to the fact that MSA is both selective and differential media . Due to the colour change of the MSA agar it was due to the fact that was fermented to acid , therefore the streptococcus bacteria are thus differentiated from colonies of bacteria that do not ferment mannitol. Only bacteria that grow at a high salt concentration  and ferment mannitol to acid can be readily identified by colour change.
For the zone of inhibition of throat swabs for students that stay off MGI residence, for Ampicillin, if the zone diameter is less than 13mm then it means that the organism is resistant to the antibiotic and if the zone diameter is more than 17mm then it means that the organism is susceptible to antibiotic. According to the results obtained, it is seen that the zone diameter for ampicillin obtained were in the range between 15mm and 30mm for 6 students, which shows that their microorganism are susceptible to ampicillin. While 6 students who got zone diameter of 10mm and below showed that their microorganisms were resistant to ampicillin and intermediate microorganisms were only 8. As compared to the non residence students' microbes, the residence student showed a distinct result as there were only 11 students who showed antibiotic resistance and 9 students showed that they were susceptible and 10 were intermediate to ampicilin.
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For the zone of inhibition, for levofloxacin if the zone diameter is less than 15 or equal to it, there is no change then the it means the organism is resistant to the antibiotic and if the zone diameter is more than 16-20mm the microorganism is intermediate then when the zone diameter is 21mm and above the microbe is susceptible to the antibiotic, in students who reside on the MGI residence there was only one student who was resistant to levofloxacin and 17 students were susceptible and only 2 were intermediate. As compared to the student off residence in resistance of levofloxacin only 4 students were resistant than 21 students showed a very distinct number to susceptibility to levofloxacin. The remaining 5 student showed an intermediate response to levofloxacin.
For the zone of inhibition of throat swabs for students that stay off MGI residence, for oxacillin, if the zone diameter is less than 10mm then it means that the organism is resistant to the antibiotic and if the zone diameter is more than 13mm then it means that the organism is susceptible to antibiotic and if the zone of inhibition was more than 11-12 the microorganism was intermediate to the antibiotic. According to the results obtained for students off residence, it is seen that the zone diameter for oxacillin obtained were in the range between 15mm and 30mm for 24 students, which shows that their microorganism are susceptible to oxacillin. While 3 students who got zone diameter of 10mm and below showed that their microorganisms were resistant to oxacillin. For students that resided on MGI residence there were 12 who showed susceptibility to the antibiotic, there were 5 students that showed an intermediate response to oxacillin and only 3 students were resistant to the antibiotic.
Zone of inhibition, for erythromycin if the zone diameter is less than 13mm or equal to it, there is no change then the it means the organism is resistant to the antibiotic and if the zone diameter is more than 14-22mm the microorganism is intermediate then when the zone diameter is 23mm and above the microbe is susceptible to the antibiotic, in students who reside on the MGI residence there was only 2 students who were resistant to erythromycin and 13 students were susceptible and only 5 were intermediate. As compared to the student off residence in resistance of erythromycin only 8 students were resistant than 13 students showed a very distinct number to susceptibility to erythromycin. Than only4 students showed an intermediate response to erythromycin.
Although there are a variety of methods that exist in the scientific world, the most common and frequent method to provide a reliable predictor of how a microorganism is likely to respond to antimicrobial therapy (antibiotics) in the infected host.
According to the results obtained, it was observed that different microorganisms are susceptible to antibiotic in both cases, student that reside on Midrand Graduate Institute residence and also those that do no reside on residence. Although there was a distinct amount of staphylococci that was found on the throat swabs on the results obtained there was also a very distinct number on streptococci microbes that were found on the tonsils.
Most of the microbes were observed to be gram-positive for both situations but there was also a small number of gram-negative microbes that were found, non -residence subjects there were about 33 gram negative microbes and in residence subjects there were no gram negative bacteria.