GI Infections II Flashcards
What is the leading cause of malnutrition in children under 5?
Diarrhoea
What physical factors can reduce incidence of GI infections?
food and water hygiene, handwashing, animal contact
What host factors can reduce incidence of GI infections?
healthy microbiome, stomach acid barrier, local immune responses
What interventions can reduce incidence of GI infections?
vaccines, antimicrobial treatments, rehydration therapies
Which organism is the most common cause of bacterial gastroenteritis in England?
Campylobacter
How is Campylobacter most commonly acquired?
Undercooked meat
Common causes of GI infections:
Intoxication vs infection?
- Infection: occurs when live bacterial cells/viruses/parasites are ingested which grow in the digestive tract and cause symptoms e.g. Salmonella infection.
- Intoxication: ingestion of pre-formed toxin
Incubation period of intoxication vs infection?
Intoxication –> rapid incubation period (minutes to hours)
Infection –> slower incubation period (hours to days)
Symptoms of intoxication vs infection?
Intoxication –> vomiting, nausea, diarrhoea, weakness, resp. failure, numbness, sensory/motor dysfunction
Infection –> diarrhoea, nausea, vomiting, abdo cramps, fever
Onward transmission of intoxication vs infection?
Intoxication –> not communicable
Infection –> person to person (faecal oral)
Factors causing intoxication vs infection?
Intoxication - inadequate cooking, improper handling temperatures
Infection - inadequate cooking, cross contamination, poor hygiene and handwashing procedures
Which organisms are the cause of foodborne gastroenteritis from;
a) dairy
b) eggs
c) meats
d) poultry?
a) Campylobacter, Salmonella species
b) Salmonella sp
c) Clostridium perfringens, Bacillus cereus, Aeromonas, Campylobacter, Salmonella sp, E coli
d) Campylobacter sp.
Does S. aureus cause food poisoning via intoxication or infection?
Intoxication - produces heat stable enterotoxin
Symptoms of S. aureus food poisoning?
N&V (can be projectile), no diarrhoea
Ibcubation time of S. aureus food poisoning??
1-4 hours after eating
Common foods causing S. aureus food poisoning?
Mayonnaise, meat, dairy
Does Bacillus cerus cause food poisoning via infection or intoxication?
Intoxication
What are the 2 types of GI illness that Bacillus cereus can cause? Which toxin causes each type?
- emetic (vomiting) syndrome –> heat stable emetic toxin
- diarrhoeal syndrome –> heat labile toxin
What is a heat stable toxin?
survives the cooking process
What is a heat labile toxin?
can be changed or destroyed at high temperatures
Symptoms of the 2 types of Bacillus cereus food poisoning?
- Vomiting syndrome (heat stable) - Vomiting but no diarrhoea
- Diarrhoea syndrome (heat labile) - Little vomiting but profuse diarrhoea
Incubation periods of the 2 types of Bacillus cereus food poisoning?
Heat stable emetic toxin –> 1-4 hours after eating
Heat labile toxin –> 12-14 hours after eating
Food source of the 2 types of Bacillus cereus food poisoning?
Heat stable emetic toxin –> cooked rice and other starchy foods
HEat labile toxin –> wide variety of foods
Which bacteria causes food poisoning from cooked rice?
Bacillus cereus
Does Clostridium perfringens cause food poisoning via intoxication or infection?
Intoxication –> heat labile toxin
Symptoms of food poisoning caused by Clostridium perfringens?
Abdominal cramps, watery diarrhoea
Incubation period of food poisoning caused by Clostridium perfringens?
1-4 hours after eating
What are the advantages of spore-forming bacteria?
Bacterial spores offer the advantage of a higher survival rate during the acidic stomach passage and better stability during the processing and storage of the food product.
Food source of food poisoning caused by Clostridium perfringens?
Meat, meat products
Does Clostridium botulinum cause poisoning via intoxication or infection?
Intoxication –> is a neurotoxin
Symptoms of Clostridium botulinum food poisoning?
- Blurred vision
- Respiratory failure
- Flaccid paralysis
- Neurological symptoms
Food source of Clostridium botulinum food poisoning?
- Improperly canned food
- Honey
What is infant botulism?
C. Botulinum spores in honey can colonise infant (<1yr) GI tract and produce toxin
- Constipation
- Neurological symptoms
- Milder disease than adults
Does Salmonella cause food poisoning via infection or intoxication?
Infection
Most common type of Salmonella?
S. enteritidis
Symptoms of Salmonella food poisoning?
Cramps, diarrhoea, fever, myalgia, nausea and vomiting
Food source of Salmonella food poisoning?
Poultry, birds and some reptiles
Why are high numbers of Salmonella needed to cause infection?
As killed by gastric acid
Incubation period of Salmonella food poisoning?
6-8 hours after eating
When should antibiotic treatment be considered for Salmonella infection?
- Are older than 50 years of age.
- Are immunocompromised.
- Have cardiac valve disease or endovascular abnormalities, including prosthetic vascular grafts.
Antibiotic treatment is not recommended for healthy people with gastroenteritis due to Salmonella infection.
What is the antibiotic treatment for Salmonella infection?
Ciprofloxacin (500mg twice a day for 1 day only)
Does Shigella sp. cause disease via infection or intoxication?
Infection
BUT some produce an enterotoxin and a Shiga toxin
What is Bacillary dysentery? What is it caused by?
A type of dysentery and a severe form of shigellosis (the term is usually restricted to Shigella infections)
What are the 3 types of Shigella sp.?
- S. dysenteriae –> most severe
- S. flexneri
- S. sonnei –> most mild (tend to see in UK)
Why are only low numbers of Shigella needed to cause infection?
Fairly resistant to killing by gastric acid
Symptoms of bacillary dysentery?
- Waterdy, bloody, mucoid stool
- Abdominal pain
- Fluid and electrolyte loss
Incubation of bacillary dysentery?
36-72 hours
Transmission of bacillary dysentery?
Found in the guts of humans, primates
Transmission via faecal oral route
When should antibiotic treatment for gastroenteritis caused by Shigella be considered?
- With severe disease.
- Who are immunocompromised.
- With bloody diarrhoea.
Antibiotic treatment is not recommended for healthy people with mild shigellosis.
What is the antibiotic treatment for gastroenteritis caused by Shigella?
Ciprofloxacin 500 mg twice a day for 1 day only (continued for 5 days if the organism is Shigella dysenteriae)
Most common symptom of Campylobacter infection?
Watery diarrhoea (also get nausea, vomiting, malaise and headache)
Does Campylobacter cause food poisoning via infection or intoxication?
Infection
Incubation period of Campylobacter infection?
2-5 days
Source and transmission of Campylobacter infection?
Poultry, birds
Faeco-oral route
When should antibiotics be considered for Campylobacter infection?
- With severe symptoms (high fever, bloody diarrhoea, or more than eight stools per day).
- Who are immunocompromised.
- Whose symptoms appear to be worsening.
- Whose symptoms have lasted longer than 1 week.
Antibiotic treatment is not usually necessary for people with mild symptoms.
Fluid and electrolyte replacement may be needed.
What is the antibiotic treatment for Campylobacter infection?
- Erythromycin (alternative: clarithromycin or azithromycin)
- Ciprofloxacin is an alternative to macrolides
Does E. coli 0157 cause disease via intoxication or infection?
Infection BUT can produce Shiga toxin
Symptoms of E. coli 0157 infection?
- Watery then blood diarrhoea
- Haemorrhagic colitis (10% develop Haemolytic Uraemic Syndrome)
Incubation period of E. coli 0157 infection?
2-5 days
Food source of E. coli 0157 infection?
Cattle and meat
What is haemolyic uraemic syndrome? Which organism is it caused by?
- E. coli 0157
- Results in acute renal failure, thrombocytopaenia, microangiopathic haemolytic anaemia
Treatment for gastroenteritis due to Vero cytotoxin-producing Escherichia coli 0157 (VTEC)?
- Management is entirely supportive; there is no specific treatment
- Do not prescribe antibiotics
- Avoid antimotility drugs, such as loperamide or diphenoxylate, and opioids
- Advise against the use of nonsteroidal anti-inflammatory drugs, such as ibuprofen (due to effect on kidneys)
Summary of other gastrointestinal E. coli infections
What are the 5 major organisms causing viral gastroenteritis?
- Rotavirus
- Adenovirus
- Norovirus
- Astrovirus
- Calicivirus
Summary of viral gastroenteritis;
Is there a rotavirus vaccine?
Yes
What is amoebic dysentry?
An infection caused by any of the amoebae of the Entamoeba genus.
PARASITIC
90% of amoebic dysentery cases are asymptomatic. When are symptoms most common?
during infection by Entamoeba histolytica
Symptoms of amoebic dysentery caused by Entamoeba histolytica?
- Watery then bloody diarrhoea
- Nausea
- Vomiting
- Tenesmus
- Malaise
Exrta-intestinal symptoms:
- Liver abscess – high fever and abdominal pain
Incubation period of Entamoeba histolytica?
15 days
Food source of Entamoeba histolytica?
Contaminated food or water
Treatment for amoebic dysentery?
Prescribe treatment for all people with confirmed amoebic dysentery (or asymptomatic amoebiasis):
- Acute invasive amoebic dysentery or liver abscess –> metronidazole or tinidazole followed by 10 day course of diloxanide furoates the drug of choice for treating giardiasis.
- Asymptomatic patients with cysts in faeces –> diloxanide furoate
What is cryptosporidiosis? Which organism causes it?
A highly contagious intestinal infection from exposure to Cryptosporidium parvum (which live in the intestines of humans and other animals and are shed through the stool).
Symptoms of cryptosporidiosis?
- Watery diarrhoea, weight loss, low grade fever
- Can be asymptomatic carrier
- Severe chronic diarrhoea in immunocompromised
Incubation period of cryptosporidiosis?
2-10 days
Food source of cryptosporidiosis?
Found in animals, fish, reptiles, common water contaminant
Treatment of cryptosporidiosis?
- Usually self limiting, therefore no treatment required
- No antibiotic treatment is necessary in immunocompetent individuals
For immunocompromised:
- Treat the underlying condition (eg HAART for HIV)
- All drugs available in the UK are of unproven benefit (paromomycin, azithromycin, clarithromycin)
- Nitazoxanide available on a named patient basis, but of unproven benefit
What is giardiasis? Which organism causes it?
Giardiasis is an infection in your small intestine caused by a parasite called Giardia intestinalis
What is the most common protozoan parasite of humans?
Giardia intestinalis
Symptoms of Giardiasis?
- Foul smelling, watery diarrhoea, cramps
- Steatorrhoea, flatulence
- Chronic relapsing diarrhoea in some
Incubation period of giardiasis?
1-4 weeks but sudden onset
Source of Giardia intestinalis?
common water contaminant
Treatment of giardia intestinalis?
Prescribe treatment for all people with confirmed giardiasis:
- Metronidazole is drug of choice
- Tinidazole is an alternative to metronidazole
Organism behind cholera?
Vibrio cholerae (bacteria)
Symptoms of cholera?
- Abrupt, water “rice water stool
- Significant fluid loss, hypervolemic shock
- Cholera toxin leads to fluid loss
Source of vibrio cholerae?
Water or food borne (esp shellfish)
Treatment of cholera?
- Basis of treatment is replacement of lost fluids
- Oral rehydration if not severe (80% of people treated successfully this way)
- Anitbiotics recommended for patients with moderate to severe dehydration (tetracycline, doxycycline, ciprofloxacin)
What is enteric fever? Which organism causes it?
- Also known as typhoid fever, is a common infectious disease in low and middle income countries. It is the commonest bacterial cause of fever in returning travellers and migrants from these areas.
- Caused by Salmonella typhi, Salmonella paratyphi –> engulfed by macrophages and migrate to liver, spleen and bone marrow
Symptoms of enteric fevers?
- Stage 1: fever, headache, Malaise, anorexia, constupation/diarrhoea
- Stage 2: diarrhoea, splenomegaly, high fever, rose spots
- 1-5% become chronic carriers
Treatment of enteric fever?
Prescribe immediate antibiotic treatment for all people with confirmed enteric fever.
–Azithromycin (5 days) is the drug of choice for treating Enteric
–Multiple resistant – fluoroquinolone (5 days) or cefixime (7-14d)
–Quinlone resistant – azithromycin (7d) or ceftriaxone (10-14d).
Antimicrobial sensitivities important to guide treatment
How common is antibiotic associated diarrhoea?
Develops in ~30% patients on antibiotics
What is the most common organism causing antibiotic associated diarrhoea?
C. difficile
How do antibiotics lead to diarrhoea?
- Antibiotics deplete normal gut flora
- C. difficile produces toxins
Symptoms of C. difficile infection?
- Foul smelling, watery diarrhoea, cramps, low grade fever
- Can lead to PMS, toxic megacolon, death
- Toxin mediated inflammation, Spores aid transmission
- Recurrence in 30%
Risk factors for C. difficile infection?
antibiotics, age >65yrs, hospital stay
What is Pseudomembranous colitis?
Pseudomembranous colitis refers to swelling or inflammation of the large intestine due to an overgrowth of Clostridioides difficile (C difficile) bacteria. This infection is a common cause of diarrhea after antibiotic use.
Treamtnet of antibiotic associated diarrhoea?
STOP predisposing antibiotic and start treatment with vancomycin, or fidaxomicin (metronidazole can be used, but only recommended in certain scenarios)
Other treatments include immunoglobulin, bezlotoxumab and faecal transplants
What is streptococcus gallolyticus associated with?
Infective endocarditis and septicaemia in elderly
BUT
Also strongly associated with colorectal cancer (not a cause, but may have a role in promoting colorectal cancer)
What should you always investigate patients with S. gallolyticus for?
Colo-rectal cancer
What is gastrointestinal tuberculosis?
GI infection caused by Mycobacterium tuberculosis
Symptoms of gastrointestinal tuberculosis?
- Abdominal pain
- Weight loss
- Anaemia
- tiredness
- Night sweats
What can gastrointestinal tuberculosis be confused with?
IBD, intestinal infections, malignancy
Treatment of GI TB?
Treatment of TB requires prolonged therapy with multiple agents to combat resistance development
For people with active TB without CNS involvement, offer:
- isoniazid (with pyridoxine), rifampicin, pyrazinamide and ethambutol for 2 months, then
- isoniazid (with pyridoxine) and rifampicin for a further 4 months.
Modify the treatment regimen according to drug susceptibility testing
