Listeria Innocculosis

AIM – The aim of the experiment is to determine the relative effectiveness of several anti-microbial substances on developing pathogens. (E. coli)

The aim of this investigation was to find out which antiseptics were most effective at preventing the growth of bacteria.

What would explain the phenomenon of a minute growth near a disc that had a clear zone of inhibition is that the agent is bacteriostatic because it is it is inhibiting the growth of the bacteria versus a bactericidal agent which just kills

37 The purpose of this latest amendment was to ultimately improve the oversight and compliance activities of R.T.E foods with respect to their potential to support the growth of Listeria. For example, it is now a requirement that environmental monitoring programs are incorporated in to all plants and are used in the production of R.T.E food products. 38 Furthermore, the definition of R.T.E foods was updated and expanded upon with regards to which foods display the potential to grow of L. monocytogenes and a more detailed list of foods prone to contamination. 39 This policy revision also focused aimed to provide an even greater focus to at protecting the high-risk members of society, specifically the infants, pregnant women and the elderly. 40 This aspect of the 2011 policy decision was greatly influenced by the European cases of listeriosis regarding the decision to utilize more efficient risk communication programs intended to protect these vulnerable groups, specifically the aging members of society. 41 The majority of European cases have been attributed to elderly population, as they are exceedingly prone to becoming ill. Therefore, this provided even more need to center the policy on these at risk groups.

The minimal inhibitory concentration is the lowest amount of the antimicrobial concentration needed to prevent the noticeable growth of the microorganism after incubating the sample overnight. Each group was given a specific antibiotic of

The second experiment will be conducted to determine which purification method is best suitable in eliminating the largest number of bacteria colonies as well as safe for drinking. These purification methods include, chlorination, boiling and filtration. The third experiment will be conducted to determine the effect of temperature on bacterial growth. Using Micrococcus Subtilus, 1ml will be grown and left to incubate at three temperatures. The incubation temperatures will be 0 Degrees Celsius, 20 Degrees Celsius and 37 Degrees

Listeria is the name of a bacteria found in soil and water and some animals, including poultry and cattle. It can be present in raw milk and foods made from raw milk. It is also found in marine environments and is often associated with fish and seafood products. Animals such as sheep, goats and cattle are

SP-D had shown the growth inhibition of E coli, Legionella pneumonia, Enterobacter aerogenes and Klebsiella pneumonia by increasing the cell membrane permeability (Wu et al., 2003) but not in the case of mycobacteria (Ariki, 2011). We performed experiment to find out either recombinant conglutinin increased the cell membrane permeability of the M. bovis BCG and as a result growth inhibited which is shown in figure 4.3. Heat-treated M. bovis BCG used as a positive control. While heat-treated M. bovis BCG were stained with propidium iodide, they absorb PI stained due to increased cell membrane permeability achieved with heating. It has been confirmed that M. bovis BCG coated with conglutinin does not kill mycobacteria by increasing cell membrane permeability as those bacteria does not shown the propidium iodide absorbance. From this experiment we observed that the direct effect of conglutinin is bacteriostatic rather then bactericidal, as no bacterial cell lysis

After entry, the bacteria are trapped in a single membrane vacuole known as the phagosome. Lm must escape from the phagosome into the cytosol by the action of the secreted pore-forming toxin, Listeriolysin O (LLO) which is encoded by hly (Portnoy et al., 2002). Getting access to the cytosol is necessary for a successful infection and failure to escape from the phagosome results in the elimination of the bacteria from tissues (Le Monnier et al., 2007). LLO belongs to a family of cholesterol- dependent cytolysins (CDCs) which are secreted as a soluble monomers and characterized by their ability to bind to the cholesterol of host membranes, oligomerize, and form a large pores (Schnupf et al., 2007). Bacterial membranes lacking sterols are therefore not affected by the action of these toxins.

Listeriosis is a serious infection that result from food contamination with the bacterium L. monocyogenes. It I known to be in fact, “one of the most deadly bacterial infections currently known- with a mean mortality rate in humans of 20 to 30% or higher despite early antibiotic treatment” 11. Besides the transmission of foodborne, it can also be transmitted from mother to fetus or human-to human physical interaction. A mother can consume contaminated food or liquid such as milk during pregnancy and be able to transmit to the fetus through the maternal blood stream or from a colonized genital tract5 (See Figure 3). This can cause serious factors leading to premature delivery, miscarriage, or other serious health issues for the newborn.5

The main objective of this experiment is to investigate the effect of different types of antibiotics on bacteria Bacillus subtilis and Escherichia coli. Some of the main methods used in this experiment

Listeriosis is a life threatening infection which is caused by eating food that has been contaminated with the bacteria “Listeria monocytogenes”. This bacterium is most commonly found in dirt, water, and plants. The people that are most likely to contract this infection are high risk populations; such as elderly people, pregnant women, young children, and people with compromised immune systems. It is estimated that 1,600 people become infected with listeriosis every year, and about 260 people die from the infection, which means 1 in 5 infected can die. A few of the symptoms are fever, muscle aches, nausea, and sometimes death.

In the experiment “Antimicrobic Sensitivity Testing: The Kirby-Bauer Method” students used six different antimicrobics to identify which antimicrobics were effective in killing four different organisms. The four different organisms that students used in this experiment were: E. coli, Proteus Vulgaris, P. aeruginosa, and S. aureus. And the six antimicrobics that students used in this experiment were: Amoxicillin, Cefoxitin, Chloramphenicol, Doxycycline, Rifampin, Vancomycin. Each organism was swabbed in a different plate of nutrients, and the six antimicrobics were placed in the plate, too. After swabbing the organism and placing the antimicrobics, the plates were incubated for forty-eight hours.

Listeria Monovytogenes is a soil opptunistic bacterium that at same time is a food borne pathogen. Though its existence in nature can be as high as 20% in soil-plant sample, the infection occurs in healthy population is rare. However, to population that have immature or compromised immune systems, it is a dangerous pathogen; its infection has a mortality rate as high as 30%. The first record of L. Monovytogenes discovery was in 1926, when Department of Pathology of the University of Cambridge routinely autopsies their laboratory animals that died during breeding, they found six rabbits that suffered sudden death have similar lesions without exposure to evident toxic or infection (). Two months later, they obtained a pure culture of gram-positive bacilli that is associated with observed disease. It was first named by the experimenters as bacterium monocytogenes and later it was categorized in to Listeria genus. After its discovery, L. Monovytogenes was found associated with neonatal sepsis and meningitis by a coincidence. In 1950, East German scientist Potel and his coworkers discovered several case of septicemia in newborn baby that have common characteristics of focal necrosis while in West Germany, scientist Seelinger found that adult suffer listeria septicemia also have similar focal necrosis(), and later, their collaborate work confirmed that L. monocytogenes is a significant pathogen in perinatal infections. However, it was not until 1981 that people

The purpose of this Literature review is to gain a broader insight into the food borne pathogen known as Listeria and its traits .In This review I will discuss in detail the different types of Listeria Species which can be isolated from various types of food samples and determining their overall antibiotic resistance, the illness associated with each and the incidences and outbreaks worldwide. I will then compare my overall findings, due to the word count I will not be discussing the Biochemical tests in this review. Over the last number of years there has been a wide variety of research and experiments carried out on this food borne opportunistic Pathogen. The title of this Literature review has been researched by