Gram Stain Test Essay

Methods Unknown microbial #398 went through several of tests in order to identify its characteristics when isolated from a urine sample of Doris, a 64- year old patient with a kidney infection. To identify unknown #398, must prepare a working and a reserve stock by the inoculation from a broth culture and by quadrant streaking method on a PEM and EMP plates. The following test procedures were incubated at 37°C for 48 hours for observation and identification for unknown #398. The identification of unknown #398 followed test procedures from Brown1.

Identification of bacteria within Unknown Culture #21 In this experiment, an unknown culture of two different types of bacteria was assigned to each person, a number of tests were performed to isolate and identify these bacterial cells. Based on knowledge from the previous experiments completed in lab, a basic understanding of each type of bacteria was used to create a flow chart that would aid the process of identifying the unknown bacteria within the culture. A gram stain that is performed initially will narrow down the types of tests certain bacteria will and will not respond to. In addition to the gram stain, some of the tests that were used include, a catalase test, an Eosin methylene blue (EMB) agar test, a bile esculin test, and a 6.5% sodium chloride (NaCl) test.

Mannitol Salt Agar (MSA) plate, MacConkey agar (MC) plate, Eosin Methylene Blue agar (EMB), and Hektoen Enteric Agar (HEA) (3). The MacConkey agar plate and the Mannitol Salt agar plate are both used in the identification of the unknown. The MC plate is a selective and differential medium. It is considered a selective medium because the bile salts and crystal violet aspect of the medium prevent the growth of gram positive bacteria (3). This medium is differential because of the lactose and neutral red.

In this experiment, we cultivated an unknown specimen containing two microorganisms. The purpose of this experiment was to use a variety of biochemical test previously learned in the lab to identify the unknown bacteria. The identification of unknown bacteria is a major part of microbiology. Microbiologist observe samples such as blood and sputum in the laboratory for the presence of microorganisms. Identifying unknown bacteria is extremely important in clinical settings because it helps physicians find treatment for infections.

The tube was placed back in incubation for 96 more hours to observe any more positives. 2.10 Catalase Test A trypticase soy agar plate was used and after incubation, four drops of 3% Hydrogen Peroxide was added to the plate to flow over the bacterial growth. A presence of bubbling was observed. 2.11 Starch Hydrolysis

Staphylococcus epidermidis is the organism that was identified based on the tests that I had conducted. The tests that I used to identify this organism were the coagulase test and the catalase test. My bacterium was beta hemolytic as well. First, a gram stain had to be done to determine whether the organism was a gram positive organism or a gram negative organism. This determined which set of tests that had to be done.

In the laboratory, identification of an unknown bacterium is often necessary. In the lab, a random sample consisting of three different bacteria was selected. The sample contained one gram-positive, one gram-negative paracolon, and one gram-negative coliform. The purpose of the experiment is to identify each of the three species that the mixture contained. After receiving an unknown mixture, the sample was streaked for isolation onto TSA, blood agar, and MacConkey plates.

Being able to identify unknown microbes from systematic testing is what makes the field of microbiology so important, especially in infectious disease control. Using the testing procedure laid out by the microbiology field we are able to identify unknown bacteria present in our everyday lives, and along the way learn a lot about their characteristics that separate them from other types of bacteria. Being able to do this is vital in order for us to understand why microbes are present in certain places, how they are able to grow and what restricts their growth, that way they can be combatted if necessary. These techniques for determining unknowns are also important for isolating and testing infectious disease microbes in order to prevent spreading. Another important aspect of being able to identify unknown microbes is the

The unknown bacteria was then tested on multiple selective and differential media. Growth was present on the MacConkey Agar and the colonies were the same color as the plate, which told me my bacteria was gram negative and did not ferment lactose. There was no growth on the Mannitol Salt Agar, and this told me the unknown was not salt tolerant and did not

Staphylococcus Aureus belongs to the extremely common bacteria of microflora of the skin and mucous membranes of the humans. These pathogens cause many infections, including superficial and deep purulent infections, poisoning, urinary tract infection etc. In the US, staphylococcus bacteria are supposed to be the leading cause of sepsis, postoperative wound and prosthesis infections. In addition, staphylococcus belongs to one of the leading causes of bacterial food poisoning. Staphylococcus Aureus is one of the most dangerous human pathogen.

The second ½ of the organism was used for gram staining. The gram stain method was performed on the unknown organism per lab manual page 42 and two gram stain reactions were identified. Organism B was gram positive cocci in grape like clusters. Because organism B was positive I could eliminate Escherichia coli, Enterobacter aerogenes and Proteus vulgaris because these bacteria would be rod shapes. Organism A was gram negative pink rod shaped and because of gram positive morphology I could eliminate Staphylococcus aureus, Streptococcus lactis and Bacillus subtilis.

After a gram stain was done unknown #257 was identified as a gram positive organism because when observed under the microscope the organism appeared purple with cocci in clusters. The organism was also catalase positive which means that it produced enzyme catalase and bubbled when hydrogen peroxide was added to it. Three test were conducted based on the result of the gram staining procedure. Blood agar with a Novobiocin disk was chosen as well as DNase (DNA) and Mannitol Salts (MSA) agar. The Blood agar is a bright red, opaque plate and the streaking or the inoculation technique was a modified streaking for isolation with a heavy quadrant one.

The sterile cotton swab was inserted in the S. epidermidis culture and twirled around to obtain a specimen. The entire plate was inoculate with the swab from top to bottom, to achieve a lawn of growth. The dry forceps was used to remove the antibiotic disk into the appropriate spot on the plate. This process was repeated for the all antibiotics with aseptic technique being used. The plate was incubate with lid up on the bookshelf at room temperature for 48 hours.

After experiment on microscope under oil immersion, I learned that my Unknown is gram positive. Under the lens, the bacteria appears in purple color. Its morphology is cocci arranged in cluster. However, during decolorizing process, I put too much alcohol to the crystal violet-iodine complex making the color overly removed. That led to the result of my gram positive has slightly redish

Staphylococcus aureus Introduction/ Background information Staphylococcus aureus (S. aureus) is yellow-pigmented colonies and this is a reason for (aureus = golden) in its genus name. S. aureus is a spherical shape (Coccus), gram positive bacterium that usually present in pairs as seen in microscope.it has short chains, or bunched, grape-like clusters, non-motile, no spores and facultative anaerobic. Members of this species can survive in the aerobic or anaerobic conditions and they can adapt to any of situations. The best environment for them to grow is in dilute salt concentrations and low moisture, which partially introduces human's nasal secretions and skin's surface to be a suitable place for this microorganism to grow. This bacterial growth can lead to staphylococcal infections in skin, nose and throat of human