Definition - Illness caused by ingestion of food or water contaminated with:
- bacteria and/or their toxins
- viruses
- parasites
- chemicals
- Contamination usually arises from improper handling, preparation, or storage of food or drinks
Risk Factors - older people, children, and pregnant women
- chronic disease
- recent hx of travel
- immunocompromised state
- hx of contact food poisoning
- improper food handling and storage
- consumption of undercooked meat
- Associated with Salmonella, Campylobacter, Shiga toxin-producing E coli, and Clostridium perfringens
- consumption of raw seafood
- Associated with Norwalk-like virus, Vibrio organism, or hepatitis A
- consumption of homemade canned foods
- Associated with Clostridium botulinum
- consumption of unpasteurised soft cheeses
- Associated with Listeria,Salmonella, Campylobacter, Shiga toxin-producing E coli, and Yersinia
- consumption of deli meats
- Associated with listeriosis
- consumption of unpasteurised milk or juice
- Associated with Salmonella, Campylobacter, Shiga toxin-producing E coli, and Yersinia
- consumption of raw eggs
- Associated with Salmonella
Differential diagnosis - Acute viral syndromes
- Very difficult to differentiate
- Lack of exposure to specific foods or absence of specific behaviours may help in differentiating
- Crohn's disease
- May present with fatigue, diarrhoea, abdominal pain, weight loss, fever, and rectal bleeding
- Other signs may include:
- presence of oral ulcers, perianal skin tags, fistulae, abscesses, and sinus tracts
- abdominal exam may reveal a palpable mass in the ileocaecal area
- no mass present on digital rectal examination
- Ulcerative colitis
- May present with:
- bloody diarrhoea
- hx of lower abdominal pain
- faecal urgency
- presence of extraintestinal manifestations (e.g., erythema nodosum, acute arthropathy)
- hx of primary sclerosing cholangitis
- No mass present on digital rectal examination
- Food allergies/intolerance
- History of exposure to certain foods known to cause intolerance or allergies (milk, lactose, gluten)
- Relapsing symptoms with challenge
- Irritable bowel syndrome (IBS)
- Total duration of symptoms should be more than 6 months
- Specific criteria of combination of:
- abdominal bloating or pain relieved by defection
- association with change in stool frequency and/or consistency
- without evidence of alarm signs or symptoms
- Physical examination reveals a healthy non-toxic appearance without evidence of dehydration.
- Microscopic colitis
- Typically present in older persons, long duration symptoms, and lack of haematochezia or blood in stool
- Acute appendicitis
- Localised right lower quadrant pain and peritoneal irritation are classic (guarding)
- CT scan of the abdomen is diagnostic.
- Acute cholecystitis
- Localised pain in RUQ and a positive Murphy sign are classic symptoms
- Acute pancreatitis
- Epigastric pain radiating to the back
- History of excessive alcohol consumption in alcohol induced pancreatitis
- Acute hepatitis
- Jaundice is usually present
- Risk factors for acute hepatitis B and C include unprotected sex and IV drug use
- History of excessive alcohol consumption in alcoholic hepatitis
- History of hepatotoxic medication use or overdose in drug induced hepatitis
- Neurological signs and Kayser-Fleischer ring in Wilson's disease
- Malabsorption syndromes
- Chronic symptoms and significant malnourishment
- History of intestinal surgery
- Extraintestinal manifestations of malnourishment and malabsorption are usually present
- Large bowel obstruction
- Distention is the more common presenting symptom
- Vomiting, including vomiting of fecal matter, occur later in the course of the illness
- Small bowel obstruction
- Presents with abdominal distension and vomiting earlier on in course of the illness
- May be history of abdominal surgery
- Radiation enteritis
- Patients have a history of receiving radiation therapy
- Mesenteric ischaemia
- Sudden onset of diffuse abdominal pain
- Chronic symptoms of vague, diffuse abdominal pain may also be indicative of chronic mesenteric ischaemia
- In contrast, ishaemic colitis may cause focal or diffuse abdominal pain
- Often has a more insidious onset, over several hours or days
- Medication and drugs side-effects/toxicity
- History of drugs ingestion/use
- Diverticulitis
- Leukocytosis and fever in an older patient.
- Systemic vasculitis
- Multisystem involvement (skin, joints, blood) and chronic presentation
- Biopsy shows vasculitis pattern (leukocytoclastic, necrotising)
Epidemiology - In 1995, foodborne diseases caused in England and Wales an estimated:
- 2,366,000 illnesses
- 21,138 hospital admissions
- 718 deaths
- By 2000, this had fallen to 1,338,772 cases, 20,759 hospital admissions, and 480 deaths
- The most important pathogens identified were:
- Campylobacter
- Salmonella
- Clostridium perfringens
- Verocytotoxin-producing Escherichia coli
- The annual incidence of foodborne disease in the US is estimated to be 1 case per 4 persons
Aetiology - Ingestion of food or water contaminated with bacteria and/or their toxins, viruses, parasites, or chemicals
- Contamination usually arises from improper handling, preparation, or storage of food or drinks
Clinical features - Key common features:
- Diarrhoea
- Vomiting
- Staphylococcus aureus, Bacillus cereus, or norovirus is suspected when vomiting is the major presenting symptom
- Other features:
- Abdominal pain (common)
- Fever (common)
- Blood or mucous in stool (common)
- Dehydration (common)
- Profuse rice-water stool (uncommon)
- Suggests cholera or a similar process
- Reactive arthritis (uncommon)
- Can be seen with Salmonella, Shigella, Campylobacter, and Yersinia infections
- Skin rash (uncommon)
- Rose spot macules on the upper abdomen and hepatosplenomegaly may be seen in Salmonella typhi infection
- Erythema nodosum and exudative pharyngitis are suggestive of Yersinia infection
- Patients with Vibrio vulnificus or V alginolyticus may present with cellulitis and otitis media
- Symptoms of botulism
- Diplopia (uncommon)
- Slurred speech (uncommon)
- Poor muscle tone (uncommon)
- Difficulty swallowing (uncommon)
Pathophysiology - Diarrhoea results from the action of enterotoxins on the secretory mechanisms of the mucosa of the small intestine
- May be preformed before ingestion or produced after ingestion
- May occur:
- Without invasion (non-inflammatory)
- In the large intestine, with invasion and destruction (inflammatory)
- In some types of food poisoning vomiting is caused by a toxin acting on the CNS
- Staphylococci, Bacillus cereus
- The clinical syndrome of botulism results from the inhibition of acetylcholine release in nerve endings by the botulinum toxin
- The pathophysiological mechanisms that result in acute GI symptoms from some of the non-infectious causes of food poisoning are not well known
- e.g. naturally occurring substances such as mushrooms and toadstools and heavy metals such as arsenic, mercury, and lead
Investigations- Stool microscopy for WBC and RBC
- Easy, inexpensive, and widely available.
- Helps to differentiate invasive or inflammatory from non-invasive disease.
- Stool microscopy for WBCs and RBCs should be done in cases of:
- Patients presenting with blood in stool
- Fever
- Suspected invasive pathogens (such as Escherichia coli O157:H7)
- When other diagnoses are considered (such as inflammatory bowel disease, ischaemic or infectious colitis)
- With prolonged symptoms (3 days or more)
- Dark-field microscopy can be done to identify Vibrio cholera
- Stool culture
- Bacterial culture for enteric pathogens such as Salmonella, Shigella, and Campylobacter organisms becomes mandatory:
- In any patient with grossly bloody stools
- If a stool sample shows positive results for WBCs or blood
- If patient has fever or symptoms persisting for longer than 3 to 4 days
- If symptoms persist and the pathogen is isolated, specific treatment should be initiated
- Stool O+P
- Microscopic examination of the stool for ova and parasites
- FBC with differential
- Helps to assess the inflammatory response and the degree of haemoconcentration
- Additionally, may detect evidence of haemolytic uraemic syndrome (HUS) when Shiga toxin-producing E coli (e.g., O157:H7) is suspected
- Results:
- High WBC with most inflammatory/invasive pathogen associated diarrhoea
- Low WBC are associated with typhoid fever and some viruses
- Anaemia
- High Hb and haematocrit could reflect haemoconcentration
- Serum creatinine and electrolytes
- Should be done to rule out electrolyte abnormalities and renal dysfunction:
- In all patients with evidence of moderate or severe dehydration
- In those with severe vomiting or diarrhoea or symptoms without improvement after 24 hours
- Results:
- HUS suspected when uraemia present
- Hypokalaemic metabolic acidosis secondary to diarrhoea
- Hyper- or hyponatraemia and elevated blood urea nitrogen secondary to dehydration
- Stool/serum botulinum toxin detection test
- If patient has symptoms/signs of botulism, stool or serum should be sent for toxin identification/confirmation
- Blood culture
- Blood culture is performed to exclude bacteraemia if the patient is notably febrile (e.g., temperature >101°F [38.5°C]) and there are signs of sepsis
- Tachycardia, hypotension, poor capillary refill, tachypnea, acute mental confusion, decreased urine output
- Signs of sepsis are difficult to differentiate from signs of severe dehydration
- Amylase and lipase
- Helps to distinguish food poisoning from acute pancreatitis
- LFTs
- Helps to distinguish food poisoning from acute cholecystitis or acute hepatitis
- May be elevated in patients with wild mushroom toxicity or invasive pathogens associated with systemic illness
- Particularly Salmonella and Campylobacter
- May show hypoalbuminaemia secondary to malnourishment or as an acute-phase reactant
- Hepatitis A IgM antibodies
- Performed when history or occupation (daycare, nursing) suggestive of exposure to hepatitis A or if LFTs abnormal
- Acute abdominal series
- Flat and upright abdominal radiographs should be obtained urgently if the patient experiences severe pain or obstructive symptoms, or if perforation is suspected
- Sigmoidoscopy/colonoscopy
- Sigmoidoscopy/colonoscopy is considered in cases where:
- Bloody diarrhoea in whom no enteric pathogen has been identified
- Bloody diarrhoea persists or increases in severity
- Patients whose clinical picture and tests results are incompatible with a diagnosis of foodborne illness
- Can be useful in diagnosing inflammatory bowel disease, antibiotic-associated diarrhoea, shigellosis, and amoebic dysentery
- Colonoscopy is more expensive, requires full preparation and sedations, and should be performed in a special setting (endoscopy suite)
- Careful colonoscopy is indicated in patients with persistent symptoms or not responding well to initial treatment
- Other possible investigations
- Oesophagogastroduodenoscopy
- Immunocompromised patients
- Patients receiving chemotherapy
- Patients with persistent, severe symptoms lasting more than 5 days or not responding well to initial treatment
- Biopsy
- Considered when performing endoscopy
- May distinguish inflammatory bowel disease from acute infectious enteritis or colitis
- Presence of crypt architectural changes such as crypt branching or sparsity
- However, these features take several weeks to develop and are not likely to be present in an infectious colitis
- Duodenal aspirate
- Considered in immunocompromised patients, patients receiving chemotherapy, and patients with persistent symptoms or not responding well to initial treatment
- PCR of stool
- PCR may be useful when available to detect Campylobacter,Salmonella, and Shiga toxin-producing E coli O157 but is not widely available
Managementa) conservative- Oral hydration
- A simple oral rehydration solution (ORS) may be composed of 1 teaspoon of salt and 4 teaspoons of sugar added to 1 litre of water
- ORS promotes co-transport of glucose, sodium, and water across the gut epithelium, a mechanism unaffected in cholera
- The WHO recommends a solution containing 3.5 g of sodium chloride, 2.5 g of sodium bicarbonate, 1.5 g of potassium chloride and 20 g of glucose per litre of water
b) medical - Antiperistaltics
- Can be offered to patients with uncomplicated watery diarrhoea whose
diarrhoea interferes with their ability to work or those with
traveller’s diarrhoea
- Antiperistaltics (opiate derivatives) should not be used:
- In patients with fever, systemic toxicity, or bloody diarrhoea
- In patients whose condition either shows no improvement or deteriorates
- Antidiarrhoeals
- The value of non-prescription antiperistaltics or antidiarrhoeals (e.g., loperamide) in patients with mild-to-moderate diarrhoea is under discussion
- They can be offered to patients whose diarrhoea interferes with their ability to work or those with traveller’s diarrhoea
- Adsorbents (e.g., aluminium hydroxide) help patients have more control over the timing of defecation but do not alter the course of the disease or reduce fluid loss
- Antisecretory agents (e.g., bismuth) may be useful
- In mild cases, loperamide is safe and effective
- When invasive pathogens are suspected, antidiarrhoeals that target motility should be generally avoided
- Decrease in intestinal motility in patients taking diphenoxylate/atropine may be detrimental to those with diarrhoea resulting from Shigella or Salmonella organisms.
- IV rehydration
- Intravenous solutions are indicated in patients who are severely dehydrated or who have intractable vomiting
- Rehydrate can generally be done rapidly without complication
- For example, if there is 10% dehydration in a 75 KG adult, and the fluid deficit is 5 to 7 L, the volume can be administered over 2 to 4 hours (i.e., 2-4 L/hr)
- Potassium may be added but not to exceed 10 mEq/hour with IV administration
- Botulin antitoxin
- Notifiable, discussion with local authority/CDC for provision of antitoxin
- Antitoxin works to block the toxin produced by Clostridium botulinum
- Antibiotics
- Shigella species
- fluoroquinolone or trimethoprim/sulfamethoxazole
- Non-typhi species of Salmonella
- fluoroquinolone or trimethoprim/sulfamethoxazole
- Escherichia coli species (excluding enterohaemorrhagic [Shiga toxin-producing])
- Campylobacter species
- Yersinia species
- fluoroquinolone or doxycycline or aminoglycoside
- Vibrio cholerae + Vibrio parahaemolyticus
- fluoroquinolone or doxycycline or tetracycline or trimethoprim/sulfamethoxazole or azithromycin
- Giardia species
- Cryptosporidium species
- paromomycin or nitazoxanide
- Cystoisospora belli
- trimethoprim/sulfamethoxazole or pyrimethamine and folinic acid
- Microsporidium species and immunocompromised
- Entamoeba histolytica
- metronidazole + paramomycin or diiodohydroxyquinoline
- Listeria monocytogenes
- ampicillin or trimethoprim/sulfamethoxazole
c) surgicalPrognosis- Because most cases of food poisoning are self-limited, prolonged follow-up care is not required
- Stool cultures should be monitored in individuals working in settings such as hospitals, food establishments, and daycare centres who are infected with:
- Shiga toxin-producing Escherichia coli (e.g., O157:H7) or Salmonella or Shigella organisms
- Continue until they become culture-negative without antibiotics
- These people should not return to work until that time
- Mortality is relatively rare (<0.1%) but more likely in very young, elderly or immunocompromised persons
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