Unraveling the Impact of Bacteria on Human Health

We live in an environment full of microorganisms. These organisms may be pathogenic causing serious infections to humans and other living organisms, some just commensals while others are helpful in the food industry. The harmful effect of these organisms is a function of the condition that surrounds them at a particular time. For example, a favorable temperature, and the acidity or alkalinity of the medium in which they find themselves are some of the key factors that helps them multiply well enough to cause infection. It is a bit difficult to find a solution to a problem without knowing its causes. Therefore, it necessary that to identify the problems caused by bacteria, we need to know what actually caused it. Identifying the unknown bacteria

A pure culture of an unknown bacterium labeled # 10B test tube was handed to me by my instructor. A gram-staining kit, bibulous paper, a light microscope, inoculating needle, and API 20E system were also used.

A slide was prepared with the unknown bacteria and the Gram stain using crystal violet and safranin as the reagent, iodine as the mordant, and alcohol as the decolorizing agent. This procedure was performed to identify the gram reaction, morphology and the arrangement of the unknown bacteria. A gram negative rod with random arrangement was seen under the light microscope after the gram stain.

To further determine the species of the unknown bacteria, an API 20E was used. API 20E system utilized a plastic strip with 20 separate compartments with each compartment consisting of cupule or a depression and a small tube containing a specific dehydrated medium (1). The ONPG tube consisted of an ingredient that functioned as an internal indicator. The ADH, LDC, ODC and URE tubes contain phenol red as the indicator. The CIT, GLU, MAN, INO, SOR, RHA, SAC, MEL, AMY and ARA tubes contain bromthymol blue as an indicator. The GEL tube contains charcoal and the H2S tube contains iron salts as indicators. The TDA, IND and VP tubes contain no indicator. All the tubes contain buffers and all the tubes with the exception of the CIT and URE contain

With the exception of ODC, H2S, URE, ADH, and IDC which were slightly under-filled with the bacteria suspension and completely filled with a sterile mineral oil to provide anaerobic conditions in the chamber, the rest of the cupule were completely filled with the bacteria suspension. The suspension was infused into the tube medium through the cupule, resulting in the reconstitution of the dehydrated medium by the saline. The reconstituted medium was inoculated at 37 degree centigrade. The result was recorded after 18 – 24hours.

A test reagent of Baritts 1 and Baritts 2 were added to the VP compartment and the result was recorded after ten minutes. A drop of Kovacs was added to indole, and ferric chloride was also added to TDA. The result was subsequently recorded. Concurrent with the API test, a motility test was also performed with the unknown bacteria. The motility test was carried out using an aseptic technique where a needle was used to inoculate a motility agar with the unknown bacteria.

Results

The bacteria in question had a white transparent colony. It was found to be a gram negative rod with a positive motility test. The API 20E result was read as either negative or positive depending on the color they produced in the individual tube.

The table below gives the test