Spore forming bacteria

Transcription

1 Spore forming bacteria

2 !Spore former!bacillus!clostridium!desulfotomaculans Spore forming bacteria!gram negative!converse sulfate to sulfide!sporolactobacillus!rod shape, microaerophilic bacteria!sporpsarcina!cocci, aerobic bacteria

3 Importance of spore former in food!response to temperatures!endospore formation!resistance!morphology!cortex --peptidoglycan!germ cell wall!nuclear mass!sporulation!germination

4 Spore cycle!control of spore forming bacteria! Prevent sporulation!condition that bacteria can grow: no sporulation! Prevent activation!dormant spore: no hazard! Prevent initiation!prevent germinate spore to grow -/$#.-6$7!"#"$%$&'"()"**+ +,-./*%$&-0 1".2&0%$"3(+,-."( 4-.2%0$(+,-."( &0&$&%$&-0 5)$&'%$"3(+,-." %)$&'%$&-0

5 Bacillus cereus Food poisoning

6 Bacillus cereus! Gram positive!motile!spore forming bacteria!facultative aerobic bacteria!grows within the temperature range of C! optimum temperature C! Endospores are formed freely, in almost every cells, under conditions favorable for growth!two forms of food poisoning! Diarrhea syndrome and emetic syndrome

7 !Unique characteristic! Temperature 10 to 48 C! Produce toxins Bacillus cereus!diarrhea toxin: Diarrhea syndrome (toxin formed in intestine)! Heat-labile enterotoxin! Large MW!Emetic toxin: Emetic (Food intoxication)! Heat stable toxin (121 C for 90 min)! Low MW! Not destroy by refrigeration and cooking! Infective dose: high infective dose (>10 5 CFU/g)

8 Bacillus cereus food poisoning! Foodborne intoxication!incubation period: 1-5 hrs (8-16 hrs:diarrhea syndrome)!duration of illness: 6-24 hrs!clinical signs! Diarrhea type!watery diarrhea!abdominal cramps!nausea but vomiting rarely occurs!symptoms persist for 24 hrs! Emetic type!sudden onset of vomiting!abdominal cramps!some patients may develop diarrhea! Usually self limiting and not severe

9 Bacillus cereus outbreaks! Most common: Rice or cereal product! High carbohydrate food! Starchy!Wide variety of foods including meats, milk, vegetables and fish have been associated with diarrheal type!all ages are susceptible to B. cereus food poisoning! Symptoms similar to Staphyloccus food poisoning (emetic type) and C. perfingens food poisoning (diarrheal type)

10 Bacillus cereus outbreak!emetic syndrome! Associated with Chinese restaurant! Fried rice! The practices flavor to food poisoning!the preparation of large amount of cooked rice (some B. cereus can survive)!holding the cooked rice at warm temperature for long periods (B. cereus spores can germinate and the vegetative cells multiply and form enterotoxin)!the toxin can survive the stir-fry temperature

11 Bacillus cereus case study! B. cereus food poisoning account for only 2% of outbreaks! B. cereus food poisoning associated with Fried rice! 2 daycare centers:!acute gastroenteritis!following lunch!lunch served to 82 children, 9 adults!nausea, vomit, abdominal cramps and diarrhea!median incubation period: 2 hrs!symptom resolved: 4 hrs after onset

12 Bacillus cereus case study!interview cases!chicken fried rice!prepare at a local restaurant!29% of persons who ate fried rice compare to 0% who did not eat!leftover chicken fried rice!b. cereus > 10 6 CFU/gm!Source of contamination?! Rice had been cooked at night! Cooled at room temperature before refrigeration! In the morning rice was pan-fried and delivery to the day care! Foods was served at noon

13 Bacillus cereus!bacillus cereus prevention and control!education!control cooking temperature, storage temperature!proper temperature!< 5 C or > 60 C!Reheating before serving!limit condition for B. cereus!ph < 5!Temperature < 5!Water activity < 0.95

14 Isolation of Bacillus cereus!suspected food, vomitus and feces of patients!selective media for B. cereus! Polymyxin B: Inhibit Gram negative bacteria! Egg yolk: Bacteria produce lecithinase! Manitol: B. cereus fermented manitol! ph indicator-bromthymol blue! Colony: Distinctive blue color surrounded by precipitation of egg yolk blue zone! Serology typing for B. cereus enterotoxin is developed!vomiting type toxin can be detected by animal models

15 Botulisum

16 Clostridium botulinum! Gram positive!rod shape!spore forming bacteria!anaerobic bacteria!the spores are heat resistant and can survive in foods!seven types (A, B, C, D, E, F and G) of botulisum are recognized! based on the antigenic specificity of the toxin! Types A, B, E and F: human botulism! Types C and D: botulism in animals (Horse, cattle, poultry)

17 Clostridium botulinum!foodborne botulism (Foodborne intoxication)! Distinct from wound botulism and infant botulism! Severe type of food poisoning! Ingestion of foods containing the potent neurotoxin!neurotoxin! Heat labile and can be destroyed if heated at 80oC for 10 minutes or longer.!the incidence of the disease is low,! Considerable concern because of its high mortality rate

18 Clostridium botulinum!unique characteristic! Strict anaerobic bacteria! Heat labile toxin! Produce neurotoxin!infective dose: Low infective dose! A very small amount (a few nanograms) of toxin can cause illness

19 ! Foodborne intoxication Botulisum!Incubation period: hrs (Usually hrs)!duration of illness: 1-8 days (or slow recovery over 6-8 mts)!four types of botulism! Foodborne! Infant! Wound (not related to food)! A form of botulism whose classification is as yet undetermined!neurotoxin cause food intoxication! High mortality rate

20 Botulisum!Clinical signs of intoxication! Marked fatigue! weakness and dizziness! usually followed by double vision! Progressive difficulty in speaking and swallowing! Difficulty in breathing, weakness of other muscles, abdominal distention! Clinical symptoms of infant botulism! Constipation! Poor feeding, lethargy, weakness, pooled oral secretions, and altered cry! Loss of head control! Recommended treatment is primarily supportive care! Antimicrobial therapy is not recommended! Infant botulism is diagnosed by demonstrating botulinal toxins and the organism in the infants' stools.

21 Infant botulisum! Infant botulism, first recognized in 1976, affects infants under 12 months of age! Caused by the ingestion of C. botulinum spores which colonize and produce toxin in the intestinal tract of infants (intestinal toxemia botulism)! Various potential environmental sources such as soil, cistern water, dust and foods! Honey is the one dietary reservoir of C. botulinum spores thus far definitively linked to infant botulism by both laboratory and epidemiologic studies! The number of confirmed infant botulism cases has increased significantly! It is now internationally recognized, with cases being reported of infant botulisum related to consumption of honey in infant

22 Botulisum!Botulinum toxin causes flaccid paralysis! Blocking motor nerve terminals at the myoneural junction! The paralysis progresses symmetrically downward!the eyes and face, to the throat, chest and extremities!the diaphragm and chest muscles! Inhibit respiration and death from asphyxia results! Recommended treatment for foodborne botulism includes early administration of botulinal antitoxin! Intensive supportive care (including mechanical breathing assistance).!the incidence of the disease: low,!the mortality rate is high if not treated immediately and properly.!rare in the United States (< 50 cases per year) (34 cases in 1994)

23 Botulism outbreak! Clostridium botulinum has been associated with! Inadequately processed, home-canned foods,! Occasionally commercially produced foods have been involved in outbreaks! Sausages, meat products, canned vegetables and seafood products have been the most frequent vehicles for human botulism!any food that is conducive to outgrowth and toxin production, that when processed allows spore survival, and is not subsequently heated before consumption can be associated with botulism!almost any type of food that is not very acidic (ph above 4.6) can support growth and toxin production by C. botulinum

24 Botulisum outbreaks!in 1987, 8 cases of type E botulism occurred! 2 in New York City and 6 in Israel! All 8 patients had consumed an uneviscerated, dry-salted, air-dried, whole whitefish! The product was made in New York City and some of it was transported by individuals to Israel! All 8 patients with botulism developed symptoms within 36 hours of consuming the food! One died, 2 required breathing assistance, 3 were treated therapeutically with antitoxin, and 3 recovered spontaneously! The food involved in this outbreak contained high levels of type E botulinal toxin despite salt levels that exceeded those sufficient to inhibit C. botulinum type E outgrowth

25 Botulism case study!foodborne botulism due to the consumption of improperly stored beef stew!a 47-year-old patient! Subacute onset of progressive dizziness, blurred vision, slurred speech, difficulty swallowing, and nausea! Examination included facial paralysis, palatal weakness, and impaired reflex! The patient developed respiratory compromise and required mechanical ventilation! Clinical signs:!why differential and tentative diagnosis included foodborne illness?

26 ! Diagnosis and treatment Botulism case study!anaerobic culture of a stool sample! Detected type A toxin! Culture of stool yielded C. botulinum!differential diagnoses included wound and foodborne botulism! Botulism antitoxin! Electromyography demonstrated an incremental response to rapid repetitive stimulation consistent with botulism!the patient was hospitalized for 49 days, including 42 days on mechanical ventilation, before being discharged

27 !Source of contamination Botulism case study! During the 24 hours before onset of symptoms! Patient had eaten home-canned green beans and a stew containing roast beef and potatoes! Although analysis of the leftover green beans was negative for botulism toxin! type A toxin was detected in the stew! The stew had been cooked, covered with a heavy lid, and left on the stove for 3 days before being eaten without reheating! No other persons had eaten the stew

28 Clostridium botulinum! C. botulinum prevention and control!education!heat treatment!temperatures necessary to kill botulism spores (> 100C for 10 minutes)!boiling food for 10 minutes before eating destroys any toxin present!proper storage!refrigeration!cooked foods should not be held at room temperatures for hours! Preservation!Low acid food!chemical: Na nitrite: prevent germination!jams and jellies: high sugar content

29 Isolation of Clostridium botulinum!to confirm the clinical diagnosis of botulism! Demonstrate the presence of toxin in the serum or feces of the patient or in the food! Mouse neutralization test: 48 hours! Culturing of specimens: 5-7 days! Selective media! Strict anaerobic condition! Incubate at C for 7 days! Biochemical confirmation

30 Perfingens food poisoning

31 Clostridium perfingens!gram positive, rod shape!spore forming bacteria!strict anaerobic bacteria!widely distributed in the environment!frequently occurs in intestines of humans and domestic animals!spores of the organism persist in soil, sediment (fecal pollution)

32 Clostridium perfingens!unique characteristic! Strict anaerobic bacterium! Produce toxins!enterotoxin!toxin production in the digestive tract is associated with sporulation! Infective dose: high infective dose (>10 5 CFU/g) (average )

33 Perfingens food poisoning! Foodborne toxicoinfection!incubation period: 8-20 hrs!duration of illness: hrs!clinical signs! Intense abdominal cramps! Diarrhea! Death as a result of dehydration and other complication (rare)! Necrotic enteritis due to the consumption of large number of organisms! Deaths from necrotic enteritis (Infection and necrosis of the intestine and from the resulting septicemia)

34 Clostridium perfingens outbreak! Most common: Temperature abuse of prepared foods! Multiply of organisms during cool down and storage of prepared food!meat and meat products!young and elderly are susceptible!usually occurs where large quantities of food are prepared several hours before serving! CDC estimates that about 10,000 cases occur annually in the U.S. (Outbreaks may under reported because the implicated foods or patients feces are not tested routinely for C. perfingens or its toxin)

35 Clostridium perfingens case study! C. perfingens food poisoning associated with Beef!1993! Following long holiday! 15 persons who become ill after eating beef purchased from the state fair! After publicized, 156 persons contact state department of health! Symptoms included!abdominal cramps!diarrhea!vomiting! No persons were hospitalized

36 Clostridium perfingens case study! C. perfingens food poisoning associated with Beef! Questionnaire! Of 156 reporting illness!144 (92%) reporting having eaten beef from one vender! Investigation!Factors?!Large demand of food during the state fair!vendor purchased 1400 pounds of raw, salt-cure beef!2-3 day before the outbreak, portion of beef were boiled for 3 hours!allowed to cool down at room temperature and refrigerated

37 Clostridium perfingens case study! C. perfingens food poisoning associated with Beef! Portion of beef were removed from refrigerator! held in a warmer (48 C)! Sliced and served! Sandwiches (beef) held and room temperature until a.m. and served!culture of samples leftover! C. perfingens 10 5 CFU/gm! Recommendation! Beef should be divided into small pieces and reheat before serving (>74 C)

38 Clostridium perfingens!bacillus cereus prevention and control!education!control cooking temperature!rapid cooling!bacteria not grow!reheat before serving