Introduction The genus Listeria contains six species, two of which are considered pathogenic: Listeria monocytogenes and Listeria ivanovii. L. monocytogenes is the only species that is associated with listeriosis in humans (1). L. monocytogenes is a Gram-positive rod, facultative anaerobe; at room temperature, it exhibits tumbling motility due to peritrichous flagella (1). It has an optimal growth temperature of 32-35oC, but L. monocytogenes can grow between 0-45oC, pH 4.4-9.4, and a water activity as low as 0.90 (1). Food processors take steps to control microbial growth at every stage of processing, and Listeria monocytogenes is of great concern for products post-processing. Viable cells have been found in soil, decaying vegetation, water, …show more content…
This was done by holding the plate up to the light to view the reaction on the agar. Afterward, the motility test medium was observed; motility appeared as an umbrella extending away from the stab line. Finally, the Micro-ID Listeria Test Procedure was followed: 1. After a 2-day incubation, the Micro-ID unit was placed flat on the bench and opened; 0.1 ml of 20% KOH was added to the inoculation well of the VP test only. The tray was then closed and held upright until the KOH flowed into the VP test solution. 2. The Micro-ID Listeria unit was then rotated clockwise at 90o so that the upper disks in the first five wells were moistened. The tray was help upright and tapped gently on the lab bench; this dislodged any suspension trapped under the upper disks. 3. All reactions were read immediately, except the VP test, as positive or negative per the color changes as listed in Appendix 1. 4. The color developed in the VP well for approximately 10 minutes prior to its reading. Results Day …show more content…
Due to contamination, the Micro-ID Listeria unit could not be used in the identification of the Listeria species used to inoculate it. This result may have something to do with the contamination visualized on our blood agar plate and oxidase test. RTE foods are under scrutiny due to the widespread outbreaks of Listeriosis over the last 2 decades. Post-processing contamination is a common pathway for L. monocytogenes to be introduced into food products because it is so widely spread in the environment (1). Once contamination occurs, L. monocytogenes can proliferate at refrigerated temperatures prior to consumer use of the food (1). RTE foods are typically not further processed after being received by consumers or retailers, which allows for Listeria monocytogenes to proliferate and infect individuals under the right circumstances. 3. What methods would a food processing company typically use to test for Listeria spp. and what tests would be used to distinguish between L. monocytogenes and L. innocua?
The Gram positive bacteria has been nicknamed Posi. The Gram positive species’ morphology includes having an opaque opacity with a smooth margin. The moisture content of the Gram positive species is shiny and the pigmentation is gold. The Gram positive species grows at an optimal temperature of 37°C. The shape of the Gram positive species is a cocci, with an arrangement of grapelike clusters. The Gram positive species’ size ranges from .5-1.5 µm. Oxygen requirement of the Gram positive species is facultative, and has complete lysis of red blood cells. All results are summarized in Table
The purpose of this study is to identify an unknown bacterium from a mixed culture, by conducting different biochemical tests. Bacteria are an integral part of our ecosystem. They can be found anywhere and identifying them becomes crucial to understanding their characteristics and their effects on other living things, especially humans. Biochemical testing helps us identify the microorganism present with great accuracy. The tests used in this experiment are rudimentary but are fundamental starting points for tests used in medical labs and helps students attain a better understanding of how tests are conducted in a real lab setting. The first step in this process is to use gram-staining technique to narrow down the unknown bacteria into one of the two big domains; gram-negative and gram-positive. Once the gram type is identified, biochemical tests are conducted to narrow down the specific bacterial species. These biochemical tests are process of elimination that relies on the bacteria’s ability to breakdown certain kinds of food sources, their respiratory abilities and other biochemical conditions found in nature.
Staphylococcus aureus could be eliminated because not only did the unknown bacteria grow, but it also didn’t change color to yellow. Lastly, a Catalase test was done by taking a colony from the Blood Agar plate.... ... middle of paper ... ...
I also inoculated a tryptic soy broth (TSB), a nutrient gelatin deep, a motility agar deep, a fluid thioglycollate medium (FTM) tube, and a TSA plate with my unknown culture. All of these inoculated media were incubated until the next class period (about 48 hours). Then when I came to class most of my inoculated tubes and my streak plate appeared to have growth. The next step I took was making a gram stain to determine the gram reaction and cellular morphology of my unknown. I used my working slant to do this, after careful examination of the gram stain, I learned that my unknown was a gram-positive bacterium. I then preceded by making a negative stain to see the size of the cells of my unknown bacteria. The cell shape was cocci and the cells occurred in clusters of tetrads. After discovering that my unknown bacteria was gram-positive cocci, I turned to page 207 of the lab manual to narrow down my options, there was only four out of the gram-positive list that were
—- . ”Tyson Foods: Living Food Safety." Tyson. Tyson, 28 Feb 2014. Web. 7 Apr 2014.
During the investigation, seven test were used to determine the unknown bacterium as Salmonella typhimurium. “Salmonella typhimurium is a genus of gram-negative, non-lactose fermenting, medium-sized, rod-shaped, bacteria, members of the family Enterobacteriaceae, most species having flagella and pili” (medical-dictionary). This bacterium is known for causing food poisoning. This illnesses usually last 4-7 days. Treatments for the illnesses caused by this bacterium are dependent upon the severity of the symptoms, the age of the patient, and the comorbidities.
Infection with C. perfringens as a food-borne illness is acquired from consumption of food or water that has come in contact with the bacterium. Some possibilities include unwashed fruits and vegetables, undercooked me...
Around the world, Joseph Lister is considered to be the “father of modern surgery” (Pitt & Aubin, 2012). Joseph Lister was a surgeon in England that not only influenced the surgery techniques of surgeons in England, but who also played a major role in the sterilization techniques that surgeons use in our country. He realized that the infections and deaths that occurred after surgery were caused by bacteria and was able to come up with a sterilization technique that would minimize the deaths of the patients. The sterilization technique that Lister used was an antiseptic method. By using the antiseptic method that used carbolic acid, Lister was able to prevent any contamination of the wound or medical instruments that were involved in performing the surgery in order to decrease the amount of deaths that occurred from infections by bacteria. Through the creation of this antiseptic technique, Joseph Lister introduced to the world an invention that improved the safety of surgery and influenced the way surgeons in other countries, such as Germany and the United States, would view microorganisms’ effect on surgical wounds eventually leading to the modernization of surgery.
Upon receiving the unknown Microorganism (M.O.) #16, I prepared a slide by cleaning and drying it. Then, using a bottle of water I placed sterile drop of water on the slide and used an inoculating loop, flame sterilized, I took a small sample of the unknown growth in my agar slant and smeared it onto the slide in a dime sized circle and then heat fixed it for ten minutes. After ten minutes had passed, I collected the ingredients needed to perform a gram stain. I got the primary stain, crystal violet, and flooded my smear for sixty seconds, and then rinsed the color off with water until the water ran clear. I then flooded the smear with the mordant, grams iodine, and let that sit on the slide for sixty seconds as well. I then rinsed the grams iodine off with water and applied alcohol to the smear to decolorize the cells; however I made sure not to over decolorize and only put enough drops on the smear till the purple ran clear. I then rinsed the slide with water and flooded the smear with safranin the counter stain and let it sit for sixty seconds and then rinsed the color off with water. I blo...
16) It is possible for foodborne illness to erupt in developed country due to improper handling and importation of food. There has been recent E.coli outbreak in developed countries like U.S (2006) and Germany (2011). However, the public health community is well prepared to respond to such
Listeria, also referred to by the name Listeriosis, is an infection that is caused by eating contaminated food containing the bacterium Listeria Monocytogenes. This particular disease can affect not only animals, but also older adults, pregnant women, newborns, and adults with weakened immune systems. When looking at these bacteria under a microscope, they appear to be small and rod-like and can sometimes be seen arranged in short chains (See Fig. 1). Because there are different species of Listeria, it may take further characterization in order to distinguish between each one. Listeria can be found in several different locations and factors. Soil is a big one, if the soil
Under the gram stain, N. meningitidis is a gram-negative diplococcus and often found within the PMN. This bacterium grows on both chocolate and blood agar culture plates. The colonies of N. meningitidis are mucoid gray and have a greenish tinge to it, whereas a non-pathogenic Neisseria colonies are dry looking. In the biochemical testing, N. meningitidis is oxidase and catalase positive. In carbohydrates utilization test, N. meningitidis is glucose and maltose positive. However, some strains of this bacterium are maltose negative. Immunologic tests are useful to see the antigen of N.
Listeria is a type of bacterium that infects humans and other warm blooded animals through contaminated food. (Dictionary.com, 2016) In other words, it is food poisoning
However, most microbial contaminants can gain access to certain meat products via raw materials, workers and equipment resulting in a public health hazard or affecting the shelf life of these products (Silva et al, 2002).
Keeping the refrigerator at a temperature of 40 ° F or less, and the freezer at 0°F, to slow the growth of bacteria. Most importantly good hand washing is key and vital for good food safety sanitation, diarrhea and other foodborne illnesses can be cut in half with just kids and staff maintaining their hands clean. Proper Storage of food after cooking is important in preventing the spread of bacteria from raw foods. Which is why it is best that raw foods should usually be store at the bottom of the fridge in order to avoid juices from dripping onto other foods or fruits. Foods should always be covered, wrapped, and stored in airtight containers in order to protect the food from