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2011-02-21 19:51:40

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  1. Which infections can cause malabsorption?
    • Giardia lambia
    • Strongyloides stercoralis
    • Intestinal TB
    • AIDS
  2. What is a common cause of tropical malabsorption?
    • Tropical sprue: india, SE asia
    • Non bloody diarrhoea +/- steatorrhoea
    • Abdo bloating
    • Significant weight loss
  3. What does duodenal biopsy of tropical sprue look like?
    Partial villous atrophy
  4. What is Rx of tropical sprue?
    • Tetracycline: for associated bacterial small bowel overgrowth
    • Folic acid
  5. If there is a case of food poisoning, what do you have do to?
    • Notifiable disease
    • Tell CCDC
  6. What are the 2 large groups of salmonella?
    • 1. Typhoid or enteric fever causing salmonella: not food poisoning or GE. They cause infections of RES – systemic. Salmonella typhia, paratyphia A, B, C
    • 2. Non-typhoid: do cause food poisoning and GE. Eg salmonella enteritidis, typhi murium
  7. How are salmonellae classified?
    Classified based on Antigenic nature of O or somatic ag that envelopes the organism.
  8. What type of organism is salmonella (gram)
    G-ve rod
  9. What is the pathogenesis of salmonella?
    • Multiplication of organisms in intestines
    • Epithelial cell damage
  10. What is incubation period of salmonella?
    16-48 hours so ask about many previous meals
  11. What are symptoms of salmonella:
    • Slight vomit
    • Moderate, maybe bloody diarhhoea
    • Abdominal pain
    • Fever as it is INVASIVE
  12. Which foods can you get salmonella from?
    Egg: because oviduct inside egg is contaminated with salmonella (raw eggs)
  13. How do you know eggs are safe?
    Lion brand in UK shows chickens that laid those eggs were vaccinated against salmonella
  14. If you cook eggs are you safe from salmonella?
  15. Which eggs do you have to be careful with?
    Cheap Spanish non red lion marked eggs
  16. How can you get salmonella without eating eggs?
    In chinese restaurant eggs swished around everywhere so if veg are in contact with surface where egg was then can get it
  17. What is the commonest cause of food poisoning in UK?
  18. What is the 2nd most common cause of food poisoning in UK?
  19. What does campylobacter look like on microscopy? Shape?
    • Gram –ve rod
    • Sea-gull shape
    • c. jejuni
  20. What is the pathogenesis of campylobacter?
    Colonises gut, multiples there, release ENTEROTOXIN in gut
  21. What is incubation period of campylobacter?
    16-48 hours so ask about many previous meals
  22. How do you compare symptoms of campylobacter with salmonella?
    Campylobacter much worse
  23. What are symptoms of campylobacter?
    • Nausea
    • Profuse bloody diarrhoea
    • Crampy abdo pain due to toxin
    • Fever as invasive
  24. Which food do you get campylobacter?
    • Chicken – it is normal flora of chicken bowel
    • Summer BBQs: brown on outside, pink inside
  25. Which 2 pathogens are ‘pure poisons’? why?
    • Bacillus cereus
    • Staph aureus
    • They produce enterotoxins
  26. What does bacillus cereus look like under microscope?
    G+ve rods (purple)
  27. Which 2 toxins does bacillus cereus produce?
    • 1. Emetic enterotoxin: is swallow enters blood stream, hits vomiting centre in brain and so vomit
    • 2. Diarrhoaegenic enterotoxin: receptors on mucosa of small and large bowel
  28. What is the incubation period of bacillus cereus and why?
    • Half hour to 6 hours get profuse vomiting first
    • Eating pre-formed toxin (as food already contaminated with toxin)
    • Inoculum effect – if eat heavily and swallowed lots of organisms get diarrhoea faster
  29. What are main symptoms of bacillus cereus?
    • Profuse vomiting
    • Diarrhoea if toxin present
    • No abdo pain or fever
  30. Which foods do you get bacillus cereus from?
    Rice: organism uses c/h in rice as energy source to produce potent toxins
  31. What is classic scenario of bacillus cereus?
    • Chinese restaurant or take-away meal
    • Cook large volumes of rice and not left in cold room or covered
  32. When you cook the rice does bacillus go? Why?
    • Flash fry the rice and so don't denature the organism as need 100 degrees to denature
    • Toxins are heat stable
  33. Where do you find bacillus?
    • They are spores
    • Found in animal and human dung and dust
    • They can land in rice and start to germinate, multiply and release toxin into culture medium
  34. What type of toxin does staph aureus secrete?
    Heat stable staph enterotoxin
  35. What is the incubation period of staph aureus and why?
    • Half hour to 6 hours get profuse vomiting first
    • Eating pre-formed toxin (as food already contaminated with toxin)
    • Inoculum effect – if eat heavily and swallowed lots of organisms get diarrhoea faster
  36. What is main symptom of staph aureus GE?
    • Profuse vomiting
    • Slight diarrhoea
  37. Which foods can you get staph aureus GE from? how
    • Milk or milk products
    • Previously due to cow mastitis, or milker having staph aureus paronychia
    • Now lots of legislation
    • On holiday – may want to milk the cows
    • Food handler: cook or chef sweating or skin flakes into pan. Some toxins denatured at high temperatures but when serve up dish and food cools down the temperature range is such that toxin can still have effect
  38. What type of organism is clostridium perfringens?
    • G+ve rod
    • Normal flora of human and animal bowel
  39. Why is it hard to diagnose c.perf diarrhoea?
    As it is normal flora so even if found in stool sample may not be abnormal. Need to locate the food source and see if it had lots of c.perf
  40. What is pathogenesis of c.perfringens?
    Multiplication of organisms and release of enterotoxin in the gut during sporulation
  41. What is incubation period of c.perf?
    12-24 hours
  42. What are main symptoms of c.perf?
    • Diarrhoea
    • Colicky abdo pain
    • No fever as toxin associated
  43. What are the 2 red meat assoc org with food poisoning?
    • c. perferingens
    • e coli
  44. where is e.coli normally found?
    Gut normal flora
  45. Which e coli can cause food poisoning? And what are its 2 other names?
    E coli O157 (all enteric organisms have a somatic O antigen) aka enterohaemorrhagic e coli, vero toxin ecoli,
  46. What is pathogenesis of e coli O157?
    • Swallow e coli (don't need much of it)
    • Colonise bowel, Multiplication of organisms and release of potent cyto entero toxins so acts on cells and receptors in mucosa of bowel causing severe bloody diarrhoea (haemorrhagic colitis)
  47. What is incubation period of E coli O157?
    16-48 hours
  48. What are symptoms of e coli O157?
    • Bloody diarrhoea
    • Crampy abdo pain
    • May be fever
  49. Why is there intense anxiety of E coli O157?
    • Linked to HUS: haemolytic uraemic syndrome
    • Renal failure
    • Death
  50. What damage can cytotoxin do?
    • In very young and very old: Cyto toxin damages RBC: haemolysis – red cell casts, blockage of renal tubules, tubular necrosis – renal failure so HUS
    • In middle aged group: toxin hits platelet: TTP (thrombotic thrombocytopenic purpura)
  51. 2 epidemiological scenarios of E coli O157
    • 1. Packaging industry at fault eg sausages
    • 2. BBQ summer – school fete – person making burger is not a food handler (quick turnover of burgers – not cooked inside), cheap burgers contaminated with animal faecal organisms
    • 3. Petting farms or zoo – inform CCDC – contact trace
  52. What is the only virus to cause food poisoning? What type of virus?
    • Norovirus (Norwalk virus/winter vomiting diseae)
    • Calicivirus
  53. What is pathogenesis of norovirus?
    Swallow virus: blunt or denude the absorptive surface of small intestine ie the villi, so decreased enzymatic activity. Get Lactose tolerant and malabsorptive diarrhoea. Transient malabsorption of fat due to decreased activity of enzymes in intestinal mucosa
  54. What is incubation period of norovirus?
    12-24 hours
  55. What was norovirus’ other name based on its structure?
    • Small round structured virus
    • Non specific structure
  56. What are symptoms of norovirus?
    • Frequent, projectile vomiting
    • EXPLOSIVE diarrhoea – non bloody (as no invasion)
    • Abdo cramps
    • Low grade fever
  57. Viral diarrhoea triad?
    • Diarrhoea
    • Vomiting
    • Fever
    • Which foods are assoc with norovirus?
    • Seafood – filter feeders
    • Oysters, muscles – eaten raw or slightly sautéed
  58. Can alco gel remove norovirus? Why?
    • Not amenable to alcogel
    • There is no lipid coat around the virus. Non enveloped virus
    • If have diarrhoea do not come to work as can spread esp COOP
    • Need chlorine based deep clean
  59. Which other food ingested toxins can give you illness but not clasically diarrhoea?
    • Botulism
    • Scrombotoxin
    • Shellfish poisoning
  60. What is the organism that causes botulism? What type is this? Where found?
    • Clostridium botulinum
    • Anaerobic organism
  61. What is the pathogenesis of botulism?
    • Normal flora of human and animal dung is swallowed
    • Germinates in gut
    • Secretes toxin which enters blood stream and acts on neuromuscular junction: ACh receptor causing flaccid paralysis.
  62. Who gets botulism?
    • Food borne – honey, very mild.
    • Drug users or skin poppers get botulism as the drugs are contaminated with botulinum when made (eg in a cowshed contaminated with dung)
  63. What is the symptom of botulism and why?
    spores into skin – necrotic – anaerobic environment – great for replication of - toxin secreted enters bloodstream. Classic symptoms: cant speak as no control over facial muscles, cant smile or speak – slurred speech.
  64. What is a serious complication of botulism and what needs to be done? Do they survive?
    • Paralysis of resp muscles and diaphragm –
    • need ITU – ventilator. Support from surrounding synapses
    • Do survive
  65. Why don't you get botulism via botox?
    Because it is diluted millions of times. But same principle
  66. Which foods is scrombotoxin associated with?
    Scromboid fish – dark meat fish: mackerel, tuna and parts of salmon, sardines, anchovies
  67. What disorder can you get with scromboid fish and how? Pathogenesis?
    Scromboid fish: Rich in histidine. When they go off – the histidine is broken down to histamine. So swallow large amounts of histamine when eat this gone off fish. As it is a vasoactive amine, histamine causes rash, tingling and numbness, light headed as vasodilatation, fall in BP. Anaphylactoid reaction
  68. What is the difference between anaphylactoid and anaphylaxis?
    • anaphylaxis as is your own mast cells that are degranulating your own histamine limitlessly
    • anaphylactoid is a finite amount of histamine you have swallowed and will easily denature
  69. What is the scrombotoxin?
  70. How do you treat the anaphylactoid reaction?
    Piriton – anti histamine
  71. What is the most common cause of severe diarrhoea in infants and children?
  72. What are the top 2 infectious disease killers in under 2yo in the world?
    • 1. Respiratory tract
    • 2. Rotavirus diarrhoea
  73. What are symptoms of rotavirus?
    Severe vomiting, diarrhoea, fever
  74. What is mode of transmission of rotavirus?
    • Faecal contamination of water
    • Water transmission
  75. What does rotavirus look like?
    Spokes of a wheel
  76. Why was WHO ORT created?
    • To tackle the rotavirus
    • Oral rehydration therapy
  77. Is there a vaccine for rotavirus? Who gets it?
    • There is a vaccine
    • Countries where poor water supply
  78. Name 4 types of viral diarrhoeas
    • 1. Rotavirus: children killer
    • 2. Norovirus: outbreaks
    • 3. Astrovirus: less severe, hardly diagnosed as doesn't last for long enough to present
    • 4. Adenovirus
  79. Name 4 types of parasitic diarrhoea
    • 1. Cryptosporidium
    • 2. Giardia lamblia
    • 3. Cyclospora
    • 4. Entamoeba histolytica
  80. Why was profile of parasitic diarrhoeas raised?
    AIDS patients prone to get severe intractable parasitic diarrhoeas especially cryptosporidium (now less with ARV)
  81. How would you describe cryptosporidium?
    • Acid fast
    • Round organism
    • Faecal organism
  82. What are the 2 epidemiological scenarios of crypto diarrhoea?
    • 1. Immunocompromised: AIDS patients – intractable diarrhoea, not killed by amount of chlorine normally found in water. No 100% anti microbial treatment for it. So practically untreatable!
    • 2. Immunocompetent: heavy rainfall or flooding lots of surface water from grazing fields containing animal faeces gets washed into reservoirs. Then cant drink tap water as normal chlorination of water does not get rid of cryptosporidium. Need to boil water then drink.
  83. Which place may you also get cryptosporidium outbreaks from?
    Public swimming pool as children pass faeces in there and chlorine cant get rid of crypto
  84. Which other animal associated parasite can cause diarrhoea?
    Giardia lamblia.
  85. What does giardia look like on microscopy?
    Trophozoite. See flagellae
  86. What is giardia assoc with?
    Crèche, nursery – children
  87. What is pathogenesis of giardia?
    Swallow cyst form – becomes trophozoite in gut – acts by blunting absorptive surface of small bowel.
  88. What is symptom of giardia?
    Malabsorptive diarrhoea – frothy, smelly, fatty stool
  89. When a child recovers from giardia, what do you have to remember in terms of feeding?
    Do not feed full strength milk – as villous processes still being regenerated. So not enough enzymatic activity to break down the lactose – takes a little time. Same for viral diarrhoea
  90. How do you treat giardia?
    • Send stool – find it
    • Rx: metronidazole, or tinidazole (variant)
  91. Which part of the world has a lot of giardia?
    St Petersburg
  92. Where can you find cyclospora?
    • Nepal or brazil
    • Not UK
  93. What kind of diarrhoea do you get with cyclospora?
    • Poorly identified diarrhoea
    • Flatulence, bloating, malabsorption.
  94. How is entamoeba histolytica spread?
    Human faeces from patient to patient
  95. Where do you find entamoeba histolytica?
    • Not in UK
    • Countries where use human faeces as fertiliser – salads contaminated
  96. What is the pathogenesis of entamoeba?
    • Swallow cyst
    • But severe invasive potential. Can produce large shaggy ulcers in large bowel
  97. What are the complications of entamoeba?
    • 1. perforation
    • 2. Trophozoites enter blood stream – travel up portal circulation and cause same destruction in liver – large liver abscess.
  98. What is the treatment of amoebic dysentery?
    Metronidazole or tinidazole
  99. What is mode of spread of travellers diarrhoea?
    Human faecal contamination of food and water (not so much animal faces)
  100. What are the 2 types of travellers diarrhoea?
    • Invasive
    • Secretory
  101. What is invasive diarrhoea?
    • Organism invades into bowel mucosa – causes ulceration – blood in faeces
    • Abdo pain
    • Fever- inflammatory diarrhoea
  102. What are 6 causes of invasive travellers diarrhoea?
    • 1. Shigella
    • 2. Enteroinvasive e.coli aka O157
    • 3. Entero-aggregative E coli
    • 4. Entero pathogenic E coli
    • 5. Salmonella
    • 6. Campylobacter
  103. How many species of shigella are there?
    • 4
    • Mildest in UK: shigella sonnei – common in public toilets. Only need to swallow 10 organisms and will get diarrhoea!
  104. Which population gets local spread of shigella?
    MSM – shigella sonnei
  105. Which shigella species releases a toxin and what is this similar to and what sequelae does it cause?
    • Shigella dysenteriae
    • Like E coli O157
    • Causes same sequalae like HUS
  106. what is the Mechanism of entero-invasive e coli?
    same as shigella and get dysentery
  107. what is mechanism for 0157?
    shiga like entero-cytotoxin
  108. what is mechanism for entero-pathogenic e coli?
    causes attachment to and effacement of villous processes
  109. who gets entero-pathogenic e coli?
    young children in outbreaks
  110. what is mechanism for entero-aggregative e coli?
    causes attachment and a mucus biofilm
  111. What are the 2 cause of secretory diarrhoea?
    • Cholera
    • Entero-toxigenic e coli
  112. what type of organism is vibrio cholera?
    • gram -ve
    • comma shaped rods
  113. What is pathogenesis of cholera?
    • Swallow org
    • Secretes toxin in gut – binds to receptor in gut mucosa – as soon as binds – the invasive proteins enter cell and take over regulation of cAMP.
    • Increase cAMP and do not switch off so net movement of water and electrolytes from the enterocytes into the lumen (reversal of ATPase pump)
  114. What are stools in cholera described as and why?
    • Ricewater stool
    • As purging own ISOTONIC FLUID
    • Very little stool
    • Flakes of mucus = rice
  115. What are consequences of cholera infection?
    Dehydration, acute tubular necrosis
  116. Which areas of the world do you get cholera?
    • Where safe water is a problem – contamination
    • Refugee camps classically.
    • Water stored in tanks. One case of cholera will spread
  117. What is the Rx of cholera?
    • Fluid replenishment
    • Antibiotics: not to Rx the patient, but to decrease the load that comes out per ml of faeces! Eg ciprofloxacin or tetracycline – decrease the spread
  118. What is the main differential of cholera?
    E tec
  119. What is Enterotoxigenic e coli?
    • Acquired gene from cholera toxin
    • Milder disease than cholera, recover faster in e tec
  120. Is there a cholera vaccine?
    Yes but not very successful
  121. What is antibiotic associated colitis linked with?
    • Clostridium difficile
    • Anaerobic
    • 5-10% of pop carry it in gut
  122. what is the spectrum of disease of antibiotic associated colitis?
    • asymptomativ disease
    • mild mod severe diarrhoea
    • pseudomembranous colitis - need colectomy
  123. what type of organism is c diff?
    G+ve anaerobe
  124. what is Rx of C diff diarrhoea?
    • INFECTION CONTROL: ENTERIC CONTROL - side room. wear gloves and aprons, wash hands before and after soap and water
    • 1. stop antibiotic
    • 2. oral metronidazole (or iv or rectal)
    • 3. ORAL (as does not leave gut into bloodstream) vancomycin if severe
    • 4. if normal bowel - faecal enema (partners)
    • 5. colectomy if pseudomembranous colitis and toxic dilatation
  125. if it is mild c-diff what Rx can be given?
    oral pro-biotics eg yeasts and lactobacilli
  126. what does pseudomembranous colitis look like?
    white plaques
  127. which abx are associated with C-diff diarrhoea?
    • broad spectrum - normal flora changed
    • all beta lactams: esp cephalosporins, clindamycin
    • quinolones: ciprofloxacin
  128. how do you diagnose bacterial GE?
    stool culture and drug susceptibility
  129. how do you diagnose viral GE?
    PCR and EM on stool sample
  130. how do you diagnose parasitic GE?
    stool stained microscopy
  131. how to diagnose antibiotic assoc colitis?
    • stool sample
    • look for toxin by immunochromatograph
    • ELISA
  132. what is the management of food poisoning?
    • replace water and electrolytes
    • antibiotics play not part in food borne diarrhoea
    • self limiting illness
    • best thing is to purge organism out of system
  133. when can you give abx in foodborne diarrhoea?
    • must justify it
    • 1. very young and very old
    • 2. any underlying immunocompromise AIDS haematological malignancy
    • 3. severe systemic toxicity - look sepsis, high WBC, organism in blood culture
  134. what is empirical abx given in GE if justified? and exception?
    • ciprofloxacin
    • except if suspect campylobacter as 40% in UK are resistant to cipro
  135. how treat campylobacter? why resistant to cipro
    • erythromycin
    • resistant as cipro was used to give chickens!
  136. in children if suspect e coli O157 how do you manage?
    do not treat as higher risk they get HUS
  137. when should you not give loperamide?
    • if you think you have toxic diarrhoea
    • as run risk of toxic megacolon
    • eg bloody diarrhoea don't take
  138. how to treat travellers diarrhoea?