Infectious Diarrhoea Flashcards
Define Diarrhoea
SUBJECTIVE
A condition in which faeces are discharged from the bowels frequently and in a liquid form.
Define Dysentry
OBVIOUS
Infection of the intestines resulting in severe diarrhoea (sometimes with the presence of blood and mucus in the faeces.)
Define Gastroenteritis
OBJECTIVE
3+ stools in 24 hours plus at least one of the following:
- Fever
- Vomiting
- Pain
- Blood / Mucus in Stools
What defense mechanisms do we have against dysentery and gastroenteritis?
- Age
- Hygiene
- Gastric Acid
- Gut Motility
- Normal Flora
- Gut Immunity
What are the two main mechanism of diarrhoea?
- Toxin
- Invasion
What are the types of diarrhoea?
Non-Inflammatory (cholera)
Inflammatory (shigella)
Mixed picture (C. difficile)
What is non-inflammatory diarrhoea?
- Toxin-Mediated
- Watery stools, rapid dehydration, relatively little abdominal pain.
- Rehydration therapy is main treatment
What is inflammatory diarrhoea?
- Bacterial Infection
- Bloody stools, systematic upset, abdominal pain.
- Rehydration is main treatment. Antimicrobials may be required.
What two organism contamination are often associated with intensely farmed livestock?
- Campylobacter
- Salmonella
What are the main factors which increase the prevalence of GI infections?
- Farming
- Storage
- Transport
- Poor Sterilisation
- Manual cross-infection
- Raw egg consumption
What is the incidence of Salmonella and Campylobacter in the UK?
100 / 100,000
What is a “novel” organism?
“Any living organism that possesses a novel combination of genetic material obtained through the use of modern biotechnology” - Basically GMO shit.
List two epidemics centred around novel organisms.
- Listeria Monocytogenes
- E. Coli O157
What would you look for in patient assessment?
Symptoms: Duration of diarrhoea. Frequency and “quality” of stool.
Risk Factors: food, occupation, travel, antimicrobials, contacts, institution.
Examination of hydration and SIRS: Pulse. Fever. Skin turgor. Urine flow. Patient appearance. Muscle cramps.
What’s SIRS?
Systemic inflammatory response syndrome (SIRS) is an inflammatory state affecting the whole body.
What investigations do you do for diarrhoea?
- Stool and Blood Culture
- Renal function
- Blood count (haemolysis)
- Sigmoidoscopy
- X Ray
- Serology
What are some differentials with a patient presenting with Diarrhoea?
- Diarrhoea as part of response to sepsis.
- Inflammatory bowel disease (If Duration > 2 Weeks)
What are treatment options for diarrhoea?
- Rehydration
- Fasting
- Antimicrobials
- Treatment of complications
What are the characteristics of Salmonella?
- Symptom onset usually less than 48h after exposure and diarrhoea.
- <5% of cases have positive blood cultures.
- Extraintestinal manifestations uncommon, but potentially fatal consensus view on antibiotic treatment.
- 20% have persistently positive stools at 20 / 52
- 27% have IBS symptoms at 6 months.
What are the characteristics of Campylobacter?
- Most common foodborne pathogen.
- Incubation up to 7 days.
- Infection clears within 3 weeks.
- Severe abdominal pain +/- colitic picture.
- Rarely invasive (immunocompromised) <1%.
- Post Infective sequelae
What are the characteristics of E.Coli O157:H7?
- Enterohaemmorhagic E.coli
- Excretion over three weeks after symptoms.
- Produces SLT (shiga-like toxins)
- HUS largely a complication in children and elderly.
- 5 to 9 days between onset of diarrhoea and HUS
What pathogen is a model for toxin-mediated diarrhoea?
Cholera
- Antimicrobial Resistance
- Vaccine
What are the characteristics of Shigella?
- Largely a disease of childhood / travel.
- HUS and seizures may complicate.
- Widespread quinolone use against shigellosis in developing world leading to resistance.
- Different serotypes hamper the development of a universal vaccine.
What is traveller’s diarrhoea?
- About 1/3 travellers develop a bout of diarrhoea.
- Usually lasts less than 1 week, but persistent diarrhoea in 1-3%
- Significant shortening by antibiotics.
- 80% of tourist infections are caused by E.Coli, Campylobacter and Shigella.
