Food Borne Pathogen full report
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31-03-2010, 07:24 AM

Food Borne Pathogen

Presented By:
Meghanath Prabhu

Staph aureus “ pyogenic lesions “ golden yellow, orange colonies.
Staph epidermis “ normal skin “ white colonies.
Staph citreus “ lemon yellow colonies.
At present 32 spp. and 15 subspp.
Staphylococci infection
Cultural characteristics
Staphylococci exists in air, dust, sewage, water, milk, environmental surfaces, humans and animals.
Humans and animals are the primary reservoirs.
Staphylococci are present in the nasal passages, throats, hair or skin of 50% or more of healthy individuals. This incidence is even higher for those who are in contact with sick individuals and hospital environments.
The Staph aureus organism is highly vulnerable to heat treatment and sanitizing agents.
Therefore, its presence in processed foods or on food processing equipment is generally an indication of poor sanitation or handling.
Mainly strains of S. aureus are capable of producing a highly heat-stable toxin that causes illness in humans.
Cytolytic toxins
Membrane active substances consisting of four hemolysin (a, ß, , d) and a leucocidin.
Toxic shock syndrome toxin (TSST)- superantigens.
Exfoliative toxin (ET) (epidermolytic)- responsible for SSSS.
Enterotoxins- Stapylococcal food poisoning, most heat resistant toxins of all toxins “ heating at 100 oC for 1hr - no destruction.
Source of contamination
In outbreak situations- Food handlers, equipment and environmental surfaces
Foods that require considerable handling during preparation and that are kept at slightly elevated temperatures after preparation are frequently involved in staphylococcal food poisoning.
Type of food
Foods most frequently implicated include meat and meat products; poultry and egg products; salads cream-filled pastries, cream pies and chocolate eclairs; sandwich fillings; and milk and dairy products.
Human illness - ingesting the toxins formed in the food by some strains of Staph aureus, usually because the food has not been kept hot enough (>60º c) or cold enough (<5º c).
The mature protein is a single polypeptide chain with a molecular weight of approx 28KD and an isoelectric point (pI) of 7.2. Consists of 239 amino acid residues, has 2 distinct tightly "packed" domains that have a very complex tertiary structure. It is this compact structure that enables SEB to be highly stable.
TSST-1 can be boiled for more than 1 h without detectable loss of biological activity, and it is not cleaved after prolonged exposure to proteases, including trypsin, chymotrypsin, and papain, which are all found in the intestinal lumen.
Different types of SEs are named alphabetically from A-I.
Ribbon structure
Mechanism of toxicity
Many of the effects of staphylococcal enterotoxin are mediated by stimulation of T lymphocytes of the host's immune system. The toxin binds directly to the major histocompatability complex (MHC) class II proteins on target cells, subsequently stimulating the proliferation of large numbers of T lymphocytes.
SE is a "bacterial superantigen" because it can form a "bridge" between the MHC II on the antigen presenting cells and the T-cell receptors on both CD4 and CD8 T cells, thereby bypassing the normal antigen processing and presenting mechanism. This bridging effect causes the release of massive amounts of cytokines, specifically interleukin 2 (IL-2), tumor necrosis factor b (TNF-b), and interferons.

Mechanism of toxicity
The cytokines cause a recruitment of additional inflammatory cells but there is a relative deficient activation of negative counter-regulatory feedback loops.
When taken together, the body's own inflammatory response most likely mediates many of the toxic effects of SE. Ingestion of SE produces profound gastrointestinal (GI) symptoms, including anorexia, nausea, vomiting, and diarrhea.
This are believed to be mediated through the release of cytokines from T cells in the lamina propria of the intestines.
Disease Frequency
Individuals differ in the susceptibility to SE.
Some may become very ill LUCKY few may be affected little or not at all.
Incubation period ranges from 1 to 7 hrs
Age - Very young and elderly persons are likely the most susceptible to a complicated course.
- Prehospital Care
Treatment of staphylococcal enterotoxin illness is supportive.
In the event of dehydration, vigorous administration of intravenous fluids is recommended.
For patients exposed via inhalation, supportive treatment with humidified oxygen may be all that is necessary, although significant exposure may assist ventilation with high oxygen concentrations.
Mechanical ventilation may be required in severe cases.
Antibiotics have not demonstrated efficacy in SE intoxication, and steroids have not been shown to be effective in SE-induced pulmonary edema.
-salivation, nausea, vomiting, retching, abdominal cramping and diarrhea.
Blood and mucus may be found in stools and vomitus in severe case.
Headache, muscular cramping, sweating, chills, shock, shallow respiration may also occur.
Duration is brief “ a day or two, and recovery is generally uneventful and complete, mortality is low.
Proper sanitation procedures to limit post-production contamination.
Proper food handling practices to limit contamination by handlers.
Proper post-production storage temperatures.
General sanitation methods can be followed to reduce contamination.
Toxin immunosensors
A variant of the classical ELISA is the dipstick sandwich assay which has been established for the detection of staphylococcal enterotoxins (SEs).
Capture antibodies for SE are deposited on a polystyrene stick which is dipped in homogenized cheese samples contaminated with SE. A typical sandwich assay is performed by subsequent addition of primary antibodies conjugated to horsershoe peroxidase (HRP).
The assembly is transferred to a tube containing H2O2 and o-diaminobenzene dihydrochloride. This substrate is converted enzymatically into a bluecolored reaction product in the presence of HRP. The optical density of the solution can be read out at 490 nm with a commercial fiber-optic probe after 5“10 min reaction time.
Stapyloccocal toxins and Bioterorism
Staphylococcal toxins could potentially be used as a biological agent either by contamination of food/water or by aerosolization and inhalation.
Breathing in low doses of staphylococcal enterotoxin may cause fever, cough, difficulty breathing, headache, and some vomiting and nausea. High doses of the toxin have a much more serious effect.
Mantis NJ. Vaccines against the category B toxins: Staphylococcal enterotoxin B, epsilon toxin and ricin. Adv Drug Deliv Rev. Jun 17 2005;57(9):1424-39.
Soto CM, Martin BD, Sapsford KE, Blum AS, Ratna BR. Toward single molecule detection of staphylococcal enterotoxin B: mobile sandwich immunoassay on gliding microtubules. Anal Chem. Jul 15 2008;80(14):5433-40.
Simone S. Moises & Michael Schäferling; Toxin immunosensors and sensor arrays for food quality control, Bioanal Rev (2009) 1:73“104
Uyen Tran, Thomas Boyle; Staphylococcal enterotoxin B initiates protein kinase C translocation Molecular and Cellular Biochemistry 288: 171“178, 2006
MARTIN M. DINGES, PAUL M. ORWIN, Exotoxins of Staphylococcus aureus CLINICAL MICROBIOLOGY REVIEWSJan. 2000, p. 16“34 Vol. 13, No. 1
Papageorgiou AC, Tranter HS, Acharya KR. Crystal structure of microbial superantigen staphylococcal enterotoxin B at 1.5 A resolution: implications for superantigen recognition by MHC class II molecules and T-cell receptors. J Mol Biol. Mar 20 1998;277(1):61-79.

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13-07-2010, 04:16 PM

It is in the process of choosing what would be the best food production. The report was very systematic because of the function of all food that much better. This will be a good advantage for the good result of the food borne pathogen.

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