How Do Microorganisms Cause Infection?

An unknown bacterium was handed out by Dr. Honer. The appropriate tests were prepared and applied. The first procedure that was done was the gram stain. Under a microscope, if the gram stain is purple, the bacterium is gram positive, if the stain is red, it is gram negative. The next test was the fermentation tests for glucose, sucrose and

The purpose of this lab was to identify an unknown bacteria culture using differential tests. The identification of the unknown culture was accomplished by identifying the bacteria based on its specific metabolic characteristics and morphology. It is suggested that culture 11 is a sample of Enterobacter aerogenes.

The colonies were smooth, translucent, and had a white brownish color. The Gram stain resulted in Gram positive cocci. After the Gram stain was completed, the bacteria were streaked on a Mannitol-Salt Agar plate and a Catalase test was performed. After these test were completed a Phenol Red Dextrose Fermentation tube was inoculated, and a SIM Tube inoculated.

The purpose of this lab was to identify two unknown bacteria cultures using various differential tests. The identification of these unknown cultures was accomplished by separating and differentiating possible

This experiment was conducted to find the genus and species of an unknown bacteria prescribed by the lab teacher, which was unknown bacteria GA3 in my case. Identification of unknown bacteria techniques are used on an every day basis to figure out what type of bacteria it is and to find the best method of how to treat a patient with this bacteria (1). All five “I’s” of Microbiology were used in the testing for the unknown culture. Inoculation was used several times to put the unknown culture into agar plates or into biochemical test tubes. After Inoculation of these tubes or plates, they always were placed into the incubator for further growth and development. Isolation was used to make sure we got the correct bacteria we were testing for. After each further isolation, we gram stained the culture and inspected the culture under a microscope to further help in the identification process of the unknown bacteria. Multiple tests were done on the unknown culture to make sure we were confident in what kind of bacteria the unknown was.

There are many reasons for knowing the identity of microorganisms. The reasons range from knowing the causative agent of a disease in a patient, so as to know how it can be treated, to knowing the correct microorganism to be used for making certain foods or antibiotics. This study was done by applying all of the methods that have been learned so far in the microbiology laboratory class for the identification of unknown bacteria. The identification process can be completed with a series of deferential stains and biochemical tests. Creating a dichotomous key helps to limit the amount of biochemical tests done on an unknown organism and by observation

A broth in test tube labeled #2 was used to identify the unknown organisms. A T-soy agar plate was the first media I inoculated. I used the streak isolation technique to isolate a pure strain from colonies, so that organisms can be identified. I inoculated a MacConckey to help me identify my Gram negative organism and observed that the organism was a non-lactose fermenter, then I performed a Citrase test which was negative. The last test I performed was a TSI, the butt was positive for hydrogen sulfide production and fermentation of glucose. All 3 results helped me conclude that my Gram negative organism was Proteus vulgaris. P vulgaris inhabits the human intestinal tract of human and animals. It is also found in soil, polluted water and fecal matter. This bacterium is

Each person in the class received an unknown and has to perform 8 tests in total from all the categories to verify what the unknown is they received for the class. I received unknown # 3, which has 3 options of Enterococcus faecalis, Proteus vulgaris, and Escherichia coli. In each test that I choose it must have at least one bacterium that has different results from 2 other bacteria. Moreover, I performed a motility test to identify if it is motile or not, a Morphology tests which will identify the gram staining and the cell morphology of bacteria and a Catalase to determine the presence of the catalase. Next, I performed a nitrate reduction test to detect if microorganisms are capable of reducing nitrate to nitrite, urea hydrolysis to indicate if the microorganism is capable of hydrolyzing of the urea, hydrogen sulfide production to determine the fermentation and sulfur production of the microorganism, blood agar to determine the hemolytic reaction of the bacteria, and EMB agar to distinguish the coliform bacteria from other bacteria. The purpose of doing all this is to find the unknown was to get familiar with the technique that we have to use. Furthermore, people who are working with this technique won’t be a cause for new outbreaks in society. Finally, after all these tests, I conclude my unknown is P. vulgaris. This bacteria have multiply septic metastases and this is rarely causes by P. vulgaris, while the injection of enzyme Chondroitinase ABC of P.

After the addition of the crystal violet stain and iodine stain, both cells from the two different bacteria colonies were purple in color (Table 1). One of the two bacterium (Bacteria A) stained was transparent after the addition of the decolorizing agent whereas the other bacteria (Bacteria B) was purple (Table 1). After the addition of the Safranin counterstain, Bacteria A cells were pink/red in color while Bacteria B cells remained purple (Table 1). Table 2 shows the observations made after each biochemical test that was performed in order to identify the unknown bacterium as Shigella flexneri. In the Phenol Red broth tests, the broth in the PR Glucose tube had changed from a red to yellow color and there were bubbles present in the tube after incubation (Table 2). In both the PR Lactose and PR Sucrose broth tubes, the broth remained red in color and there were no bubbles present in the tubes (Table 2). In the Methyl Red test, the broth immediately turned red in color after three drops of the Methyl Red reagent (Table 2). In the Voges-Proskauer test, the broth color was unchanged after the addition of VP reagent A and VP reagent B (Table 2). In the Urea hydrolysis test, the inoculated urease broth tube was an orange/yellow color after incubation (Table 2). In the citrate utilization test, the inoculated Simmons Citrate slants

Enterococcus cacae isolated from human stool differs because of its inability to produce acid from arabinose, lactose, and mannitol. Enterococcus camelliae was isolate from fermented tea leaves in Thailand; they are unable to produce acid from D-galactose and lactose. Enterococcus canis was isolated from rectal swabs and chronic otitis in dogs; they are unable to hydrolyse arginine or to grow on selective media that contain 0.04% azide. Enterococcus avium Enterococcus pseudoavium differs from their inability to produce acid from lactose. Enterococcus hermanniensis differ from the inability to produce acid from substrates. Enterococcus lactis are atypical and are isolated in raw milk Italian cheeses. Enterococcus quebecensis and Enterococcus termitis are negative for the Voges-Proskauer (VP) test, meaning that as a result of fermentation, acid is not produced. Enterococcus rivorum growth at 45ᵒC or in a 6.5% NaCl broth there is little or no growth. Enterococcus ureasiticus has a urease activity production. Some species found in water or on plants differ because they can produce pigments such as Enterococcus ureilyticus and Enterococcus rotai. The most common species seen in humans are Enterococcus facalis and Enterococcus faecium which through testing has shown a resistance to clindamycin and oxacillin but

Additional materials were, pH strips, test tubes, P-200 micropipette, 3-mL syringe and fermentation jar. The pH was measured with the aid of pH indicator strips, to determine if the pH was dropping or rising. The dilutions were performed with the P-200 micropippetor, the dilution factors changes through the experiment, in relation to the bacterial growth and ranged from 10-1 to 10-5. The fermentation jar was packed with ¼ of a head of lettuce and 5% salt-water solution from the sink. The 5% solution was achieved by using 25g of salt in 500mL of H2O. The TSA agar plates were the control environments, one aerobic and the other anaerobic. The WN5 was for the anaerobic and microaerophilic conditions and had cyclohexane and 5% salt that selects for bacteria. The PS agar dish had CFC supplement (cetrimide, fucidin and cephalonidine) and Irgasam. The EC dish had bile salt that selected for Gram-negative bacteria. The LSA plate allowed for the differentiation of lactobacilli and streptococci. All of the above plates were incubated at room temperature of 25°C. The plates were counted for formed colonies on the following days: 0,2,7,9 and 14; also the pH was taken. The pH was taken by removing some of the fermentation liquid and placed on the indicator strip.

Once the results were obtained by the different biochemical tests, the genus and species of the organism was identified as Salmonella typhimurium. These tests were chosen because these tests are frequently used to determine Gram-negative bacteria. During the Citrate test, S. typhimurium produced a positive result, which indicated sodium carbonate was present (Pearson’s 2011). A positive result was obtained during the Methyl Red test, which indicated that the organism was capable of fermenting glucose and contained a higher hydrogen ion concentration (Pearson’s 2011). S. typhimurium produced negative results during the Indole test, which showed that tryptophan was unable to be hydrolyzed (Pearson’s 2011). The Lactose and Sucrose Ferment tests both produced negative results and no production of gas, indicating that there was no change in the pH and fermentation did not occur (Pearson’s 2011). Positive results and a gas bubble was present in the Glucose Ferment test, which concluded that S. typhimurium caused an acidic change in the pH and fermentation occurred (Pearson’s 2011). S. typhimurium produced positive results for the Nitrate Reduction test, indicating that nitrates were not reduced to nitrates by the bacterium (Pearson’s 2011). Negative results were obtained through the Urea test, which showed that S. typhimurium was unable to produce urease (Pearson’s 2011). The

In the EMB agar test, two distinct colonies due to their different in color were observed. For the one with black colonies, it was determined to be lactose fermenters, because only acid production from lactose fermentation would result in this color. As for the other colonies, they appeared to be either colorless or pinkish, this indicates that they are either sucrose fermenter or non-coliform Gram-negative strains because of their inability to ferment lactose.

How I determined that my bacteria were Pseudomonas fluorescens. The first test I began with was a gran stain to figure out if it was a gram positive or gram negative bacteria which removed half of the bacteria. With the knowledge that the bacteria were gram negative, I did the EMB test and the basic sugar tests glucose, lactose, and sucrose. The results for EMB on the bacteria was a non-fermenter, further limiting the choices. It was during the test on the sugars, that it was possible to zero in on the last couple bacteria. These test, which showed up all negative leaving me with only three bacteria, since the other all negative for sugars had to be a cocci and mine was a rod. Therefore, I was left with two test left to help, Urease and Nitrate.

In order to identify the unknown #75, there are several key concepts that should be remembered to successfully identify the bacteria. Initially a broth of an unknown was given containing both positive and negative unknown bacteria. It is important to observe aseptic technique to successfully and accurately identify the unknown bacteria that was given.