Bacillus Cereus B Cereus emetic toxin Cereulidepeptideheat stable

Bacillus Cereus

B. Cereus 毒素 • 嘔吐型毒素(emetic toxin) ― Cereulide：小peptide、heat stable • 腹瀉型毒素(diarrheal toxins) ―Enterotoxin腸毒素：分離不易、heat labile • 多種溶血素 ―Sphingomyelinase：可將sphingomyelin水解成 phospho- choline 及 ceramide 。 ―Cereolysin ―Hemolysin BL

Clostridium perfringens

自然棲息地 • in the intestines of humans and many animals and is present in soil and areas contaminated by human or animal feces

Classification of C. perfringens by toxin type C. perfringens type Toxin produced Alpha Beta Epsilon Iota A + － － － B + + + － C + + － － D + － E + － － +

產生的原因 • When you eat improperly cooked and stored foods. Bacteria are found on food after cooking, and these bacteria can multiply and cause C. perfringens food poisoning if the foods sit out and cool before refrigerating. • Commonly infected meats

症狀 • include intense abdominal cramps and watery 　diarrhea. Symptoms usually appear 6 to 24 hours after eating foods containing large numbers of C. perfringens. • 中毒菌數約106~107 cells/g

治療方法 • 外傷需進行清創手勢 • Penicillin • A high infectious dose is required; the carrier state persists for several days.

Chrysophycophyta • Amphidinium spp. • Ichthyotoxin: 有些毒素可以用來麻痺魚或減少水中 含氧 量。可以用來幫助捕魚，其中有包含choline-0 -sulfate • Neurospora crassa 可以把choline-0 -sulfate當作第二 碳源

Pyrrhophycophyta • Gonyaulax spp • heat-stable, no antidote 神經毒素 • Gonyaulax spinifera 會產生Yessotoxins (YTXs)， 產生 的症狀與 Paralytic Shellfish Poisoning (PSP) toxins相 似是一種神經毒素 • selective sodium channel blocker: 神經細胞變得不能 發射信號並且支配從神經系統切斷體的區域

Staphylococcus aureus Food Poisoning

S. aureus and food poisoning • Food poisoning is not caused by the organism but by the toxin that the organism secretes • S. aureus food poisoning is the most common form of food poisoning in the US

Properties of Staphylococcus aureus • Gram positive cocci arranged in grape like clusters • Non-sporulating • Colonies on TSA are small, creamy and golden colored

Properties of S. aureus that make it persistent in nature • Relatively heat resistant • Resistant to high concentrations of salt

Symptoms of SEs • Nausea • Severe vomiting • Abdominal cramping • Diarrhea

Pathogenicity • S. aureus infections result when staphylococci breach the body’s physical barriers • Entry of only a few hundred bacteria can result in disease • Pathogenicity results from 3 features -Structures that enable it to evade phagocytosis -Production of enzymes -Production of toxins

Adherence factors • Adherence is an essential step required for colonization a new host • Adhesin comprises of proteins covalently anchored to cell peptidoglycans • Recognize the ECM or blood plasma, including fibrinogen, fibronectin, and collagens

Adhesin • Staphylococcal protein A (Sp. A) • Fibronectin-binding proteins A and B (Fnbp. A and Fnbp. B) • Collagen-binding protein • Clumping factor (Clf) A and B proteins.

The enzymes secreted by S. aureus 1. 2. 3. Coagulase – Triggers blood clotting Hyaluronidase – Breaks down hyaluronic acid, enabling the bacteria to spread between cells Staphylokinase – Dissolves fibrin threads in blood clots, allowing Staphylococcus aureus to free itself from clots 4. Lipases – Digest lipids, allowing staphylococcus to grow on the skin’s surface and in cutaneous oil glands 5. -lactamase – – Breaks down penicillin Allows the bacteria to survive treatment with -lactam antimicrobial drugs

Three groups of exotoxin secreted by S. aureus 1. Cytolytic toxins( α-Toxin, β-Toxin) -Disrupts the cytoplasmic membrane of a variety of cells -Leukocidin can lyse leukocytes specifically 2. Exfoliative toxins - Causes the patient’s skin cells to separate from each other and slough off the body - staphylococcal scalded skin syndrome (SSSS)

Three groups of exotoxin secreted by S. aureus 3. Toxic-shock-syndrome toxin (TSST) – Causes toxic shock syndrome 4. Enterotoxins – Stimulate the intestinal muscle contractions, nausea, and intense vomiting associated with staphylococcal food poisoning

Effect of S. aureus on host immunity • chemotaxis inhibitory protein of S. aureus (CHIPS) -block neutrophil receptor for chemoattratants • staphylococcal complement inhibitor (SCIN) - C 3 convertase inhibitor blocking the formation of C 3 b on bacterium

Effect of S. aureus on host immunity • extracellular fibrinogen binding protein (Efb) -block the classical pathway and alternative pathway • staphylokinase (SAK) -binding to α-defensins stops their bactericidal properties

參考資料 • 行政院農業委員會水產試驗所： http: //www. tfrin. gov. tw/ct. asp? x. Item=159317&ct. N ode=1225&mp=1 • 維基百科 https: //zh. wikipedia. org/wiki/%E 6%9 C%89%E 6%AF %92%E 6%B 8%A 6%E 9%9 E%AD%E 6%AF%9 B%E 8%97 %BB • 環境資訊中心 http: //e-info. org. tw/node/95226 • http: //mmbr. asm. org/content/42/4/725. full. pdf