Clostridium perfringens PDF

TOXICO-INFECTIONS Toxico-Infections In toxico-infections you ingest large numbers of bacteria the illness is not caused by multiplication inside of you. The illness is caused by toxin release inside of you. There are some key characteristics common among foodborne toxico-infections: For Spore Former...

TOXICO-INFECTIONS Toxico-Infections In toxico-infections you ingest large numbers of bacteria the illness is not caused by multiplication inside of you. The illness is caused by toxin release inside of you. There are some key characteristics common among foodborne toxico-infections: For Spore Formers: 1- Ingestion of large numbers of live vegetative cells is usually necessary 2- Vegetative cells of sporeformers do not multiply in the digestive tract, but sporulate and release toxins For Gram-negative Bacteria: 1- Live cells can be ingested in moderate numbers 2- Gram-Negative cells rapidly multiply in the digestive tract 3- Many cells also die, releasing toxin - Toxins of both groups cause gastroenteritis symptoms Text modified from: Ray and Bhunia. Fundamental Food Microbiology 4th Edition CLOSTRIDIUM PERFRINGENS Clostridium perfringens Optional reading: Page 513-540 Food microbiology : fundamentals and frontiers 5th Edition Author: Michael P Doyle, Francisco Diez-Gonzalez, and Colin Hill Publisher: Washington, DC American Society for Microbiology Press, ©2019 Available as an ebook from library. Microbial Ecology Cp is widely distributed in soil, sewage, water, and the intestinal tract of different animals In the intestine it can be present both in vegetative and spore form Cp spores can survive in the environment for years Toxin Production Cp is a PROLIFIC toxin-producing bacterium, producing more than 20 important toxins and toxic enzymes. Toxins can be broadly divided into 4 categories: 1. 2. 3. 4. Membrane-damaging enzymes Pore-Forming Toxins Intracellular Toxins Hydrolytic enzymes Cp cannot produce 13/20 amino acids so breaking down host tissue is a good way to acquire amino acids Not all strains have all toxins, so each strain has different pathologies Diseases caused by Cp Cp causes several diseases in humans and agricultural animals In Humans: – – – – Gas gangrene (myonecrosis in infected wounds) (infection) Food poisoning (toxico-infection) Antibiotic-associated diarrhea (infection) Enteritis necroticans (infection) In Animals: – Poultry necrotic enteritis This is a very common aspect of Cp and it produces major economic losses for poultry producers! – Gastrointestinal disease in canines – Necrotic and hemoragic enteritis in sheep – Neonatal necrotic enteritis in horse, cattle, sheep, and pigs Cp Genomic Diversity Toxin Production and Cp Typing Kiu, R et al., 2018. An Up Cp are grouped into 7 types based on the presence of typing toxins Type A strains are associated with gas gangrene (bacteria gather at a wound that has no blood supply and produce toxin that release gas and cause tissue death – this is life threatening) Type B, C, and D strains are mostly associated with enteric diseases in animals Type F consists of isolates that produce CPE but not CPB, ETX or ITX. These strains are responsible for human toxico-infections, and antibiotic-associated diarrhea Type G produces NetB and causes necrotic enteritis in chickens Symptoms of Food Cp Toxico-Infection Symptoms first appear 6-24 hours following the ingestion of a large number of viable cells Symptoms include diarrhea and abdominal pain Nausea, vomiting, and fever can occur but are less common Fatalities are rare (mortality rate is estimated at 0.003%),are caused by dehydration, and occur among the very young, elderly, and very sick Symptoms generally resolve in 24 h This is a mild disease and is seldom reported – However, it is likely extremely common – Data from 2010 indicate that there were 1-11 million cases worldwide that year – It is likely the second most common cause of foodborne illness in the USA Symptoms of Cp Antibiotic-Associated Diarrhea Like other Clostridia Cp is a poor competitor in the gastrointestinal tract However, in patients undergoing prolonged antibiotic therapy, which disrupts the stable intestinal microbiota – there can be an overgrowth of Cp enterotoxigenic strains Cp may be responsible for 10-15% of antibiotic associated diarrhea Symptoms Associated with Cp Gas Gangrene Cp cannot synthesize amino acids – Therefore, it degrades host tissues to obtain nutrients for growth – While it does this, it produces abundant gas, which makes the conditions more suitable for further growth This infection can affect muscle, fascia, and skin – it is characterized by marked tissue destruction, sepsis, and tissue death It develops after primary tissue injury such as post-surgery, diabetes, or colon cancer Cp grows rapidly, invading and killing tissues, and producing gas that creates reduced blood flow that furthers the anaerobic environment and benefits Cp Symptoms Associated with Cp Enteritis Necroticans In humans Enteritis Necroticans is characterized by abdominal cramps, shock, bloody diarrhea, acute inflammation, and pronounced necrosis of the intestinal mucosa This is a life-threatening necrotizing infection of the GI tract with a high mortality rate Treatment is surgical removal of infected small intestine – and antibiotics Foods associated with this include undercooked pig intestines (Papua New Guinea), poorly preserved pork sausage, turkey sausage, chicken stew, salmon, and crab Usually fatal within 48 hours after the onset of symptoms CP ENTERITIS NECROTICANS Enteritis necroticans (EN) (Infection) Was endemic in post-WW2 Germany – It was likely facilitated by poor sanitary conditions and malnutrition (protein-malnourished) – It disappeared a few years after it was first recognized In Papua New Guinea it is associated with spontaneous gangrene of the small intestine without obvious cause – occurs primarily in malnourished children – Almost always fatal The cause appears to be co-consumption of contaminated pork and sweet potatoes which contain a trypsin inhibitor – trypsin in the gut could break down the B-toxin secreted by Cp Also occurs in Uganda and Indonesia in similar circumstances In developed countries diabetics (who have attenuated trypsin production) are primarily affected Enteritis necroticans (EN) (Infection) Cp type C strains cause EN in humans B-toxin is the most important toxin in this infection It appears to be produced in situ making this an infection rather than a toxico-infection FOODBORNE TOXICO-INFECTIONS Common scenarios for Toxicoinfections In 1994 in Cleveland Ohio a delicatessen prepared corned beef for a St. Patrick’s Day festival by boiling it for 3 hours, cooling it slowly at room temperature, putting it into a refrigerator for 4 days, then warming it to 48.8°C before serving Sandwiches were held at room temperature from late morning until late afternoon – They were then consumed with copious amounts of green beer 156 people became ill In Virginia on the same day in 1994, 86 people became ill from corned beef which had been frozen, brined, cooked in large pieces (5 Kg), stored in a refrigerator, and held for 90 minutes under a heat lamp The typical thing about both of these cases, is that meat product had been temperature abused. In Ohio the corned beef was cooled too slowly after being cooked, and re-heating was insufficient to kill C. perfringens In Virginia, beef was cooked in too large portions, and not adequately reheated before serving. Clostridium perfringens Gram-positive, motile, rod shaped, and forms spores, can also form small chains, anaerobic – but can tolerate some oxygen Vegetative cells are sensitive to heat (pasteurization), but spores are very heat resistant and can survive boiling for several hours They grow from 6-52°C, optimal growth temperature is 43-46°C They lack amino acid synthesis ability (they cannot produce 13 of 20 essential amino acids), therefore, they more commonly grow on high-protein foods (cooked meat products) In foods the most important factors contributing to a toxicoinfection outbreak are: 1: cooking large volumes in advance 2: allowing it to cool slowly 3: holding for a long period of time 4: serving without reheating Clostridium perfringens Cooking Kills Vegetative cells, Spores Survive Large Volumes of Food Provide an Anaerobic Environment Slow cooling provides the temperature for spores to germinate and multiply Foods Involved in Cp Outbreaks Food Type No. of Outbreaks % Beef 51 26 Mexican Food 23 12 Turkey 19 10 Chicken 9 5 Pork 8 4 Finfish 3 2 Shellfish 2 1 Vegetables 1 1 Others 46 24 Unknown 28 14 The total number of cases from outbreaks in this table were 12,234. Modified From: Bibek, R and Bhunia, A., 2008. Fundamental Food Microbiology Fourth Edition. Published by CRC Press Taylor Francis Group Growth and Survival of Cp The optimal growth temperature for Cp is 43-46C, and with a generation time of 7.1 minutes the ability to grow quickly in temperature abused foods allows the bacteria to cause toxico-infections No growth is detectable at