Week 101 Diarrhoea Flashcards
Name the Microbial Causes of acute Diarrhoea
Viruses, Bacteria, Parasites
What is the leading cause of gastroenteritis worldwide, and infects most children throughout the world in early childhood?
ROTOVIRUS
What is the second most common cause of AD in children in developed countries? It typically presents in winter months in closed communities.
NOROVIRUS
During a history from a middle aged woman with AD, you note that she owns several birds. Which pathogen is present in the GI tract of wild and domesticated birds?
Campylobacter
A patient presents with AD. A young child, that went with the family to a chicken house the previous evening, which is located next to a pet shop. What is the likely pathogen?
Salmonella. Transmission is mainly via contaminated food stuffs, and the pathogen is present in the GI tract of animals.
What is EHEC?
Enteroheamorrhagic Escheria. Coli. This is the most common cause of Diarrhoea in the US. Shed in cattle Faeces.
Can be life threatening when associated with haemolytic uraemic syndrome.
What is ETEC?
Enterotoxigenic E. Coli. Most common cause of “Travellers Diarrhoea” when in poor countries with poor sanitation. Causes tens of thousands of deaths every year in developing countries.
A photographer visiting a slum in southern India returns home with Acute Diarrhoea. They didn’t have access to good sanitation when there. What is the likely cause?
ETEC
A UN convoy is forced to stay overnight in a remote African village. They find a local well, and draw water from it. The next day all persons that drank the water have severe diarrhoea, some of them malaenic. What is the likely cause?
Cholera. Endemic in many countries with poor sanitation. Occurs in outbreaks, especially following the contamination of a water supply.
A gap year student returns home from their travels in remote Malaysian villages, and a few days later develops severe dysentry. What is the likely cause?
Though ETEC is a possibility, the severeity of symptoms suggests that this may be Shigellosis.
A 78 yr old man has been readmitted with severe ando pain and bloody diarrhoea after being discharged only 7 days ago, after you cleared up his chest infection with metronidazole. What is the likely pathogen in this instance?
Clostridium Difficile. It’s best to get these patients OUT of the ward and into isolation, as they may infect other compromised patients.
Name TWO parasites that cause AD in developed countries.
Giardiasis
Cryptosporidium
A patient arrives at your surgery describing some abdo pain and a foul smelling, pale, floating stool for the last few days. What do you suspect?
Parasitic infection with Giardia. Metronidazole is the drug of choice for treatment.
The news reports that the local village of gwynerthtrrerkjfhkdjks recently had a slurry contamination of its water supply (about a week ago). A patient now arrives at your surgery from the area, complaining of general fever and gastroenteritis. You suspect a parasite - but what is it?
Cryptosporidium. Most commonly outbreak when sewage/animal waste and water supplies get mixed up.
What is a cause of Dysentry in developing countries, other than cholera and giardiasis?
Entamoeba HIstolytica
Which bacteria causes diarrhoea with Toxin A and Toxin B?
C. Difficile.
Why is a patient that takes omeprazole more at risk of c. difficile than someone that is not taking it?
Omeprazole is a proton pump inhibitor, and it neutralises stomach acid. This compromises the gastric acid barrier to infection, increasing the risk of C. difficile infection.
What is E.Coli 0157?
An EHEC!
What is the HUS bacteria?
E.coli 0157!
What is meant by the term secretory Diarrhoea?
This means that diarrhoea is caused by either an increase in the active secretion, or the inhibition of absorbtion of water from the small intestine. There is little to no structural damage, and is usually caused by a pathogen that alters ion transfer into the lumen of the gut. Fasting does NOT help.
What is osmotic Diarrhoea?
Too much water drawn into the bowell from hyperosmolar fluid in the lumen. May be due to high consumption of sugary food, or maldigestion (due to pancreatic or coeliac disease). This is also how osmotic laxatives work. Fasting usually corrects non serious cases.
Define Virulence
A Multifactorial variable made up of virulence factors that denotes capacity to cause disease, and can be expressed as the number of cells required to elicit a specific immune response.
Give an example of a virulence factor.
Adhesion factor/Invasion Factor
Name the 5 stages in the “life cycle” of an infective illness.
- ) Incubation
- ) Prodromal period
- ) Acute Illness
- ) Decline
- ) Convalescence
Name the 6 types of bacteria
Gram +ve, Gram -ve Spirochaetes Mycoplasms Obligate intracellular parasites Filamentous
Name the 7 types of virus (I know it’s not 101 but shh!)
RNA Double strand (DS) Naked (N) RNA negative single strand (-SS) enveloped (e) rna +SS N DNA SS N DNA DS N DNA DS E
Name an OTC treatment for Diarrhoea, and describe its method action including cell receptor type.
Loperamide. Acts on opiod receptors in the gut (but adapted so as not to work on the brain) and slows gut motility. This reduces symptomatic diarrhoea.
What is “acute febrile illness”?
A type of illness characterised by a the sudden onset of pyrexia.
Why is BP not a valuable sign in children?
They have very efficient CV sysrem and myocardium, allowing a huge degree of compensation for failing pressure regulating systems. This means that when and if they do go - they crash BIG TIME.
How is acute diarrhoea defined?
More than three cases of loose stools in a 24 hr period.
What are the clinical signs of SEVERE dehydration in children with diarrhoea, and how do you treat it?
Two or more of:
- Lethargy or unconsciousness
- Sunken eyes
- Inability to drink
- Skin pinch >2 seconds
Treatment is to give fluids for severe dehydration.
Infants: First 30 ml/kg in one hour, then 70 ml/kg over 5 hours.
Children (12/12 to 5 years): 30 ml/kg in 30 minutes, then 70ml/kg over 2.5 hours.
What are the clinical signs of MILD dehydration? How would you treat this?
Two or more of:
Restlessness/Irritability
Sunken Eyes
Drinks eagerly/thirsty
Skin pinch goes back slowly but not >2s.
Give fluid and food for rehydration, including oral rehydration solution if appropriate. Advise on home treatment and when to return immediately. Follow up after 5 days if not improving.
Which mineral is lost from children in diarrhoea and must be replaced?
ZINC
Why is normal saline IV not an appropriate bolus for a child with AD and SAM (severe acute malnutrition)?
With SAM, cardiac function is reduced and total sodium is actually quite high, despite plasma sodium being relatively low. The risk of CV events is increased, and so low sodium content IV at much lower dose intervals will be required.
A Nurse on your ward tells you that the severely dehydrated child you are about to see is in clinical shock. Which signs do you expect to see?
Decreased Conscious level or unconscious pale or mottled skin cold extremities Tachycardia Tachypnoea Weak peripheral pulses Prolonged Cap refill time Hypotension (decompensated shock)
What are the key aims of primary prevention?
Stop the onset of disease
Alter or remove risk factors for a disease
What are the key aims of secondary prevention?
Halt the progression of a disease once it’s established
Early detection or diagnosis followed by prompt treatment
i.e. Screening for breast cancer
What are the key aims of Tertiary prevention?
Minimising the impact of established disease
Improve quality of live if the disease can not be cured
I.E Rehabilitation after stroke
What is absolute risk?
Synonymous with incidence. The probability of an event in a population under study.
What does “absolute risk reduction” mean?
The amount by a which the risk of a disease is reduced by elimination or control of a particular exposure.
What is ALPHA or TYPE1 error?
This is saying that something IS significant, when in fact is NOT. I.E Measles vaccine causes autism.
What is Type 2 or BETA error?
This is saying that something is NOT significant, when in fact it IS. This is USUALLY less severe than Type 1 (Alpha) Error
Burkitt’s lymphoma is caused by which virus?
Epstein-Barr
What is a case control study?
A study which starts with the ID of people with a particular disease (or other health related state) of interest, and a suitable control. It then compares the exposure of these groups to the factor or factors of interest. I.E Does smoking have an impact on lung cancer incidence?
What is a case report?
A descriptive account of a case of a condition of interest
What is a case series?
A descriptive account of a series of cases of a condition of interest, often highlighting similarities.
What is a cohort study?
A study which starts with the identification of a group with a risk factor, and another without. It then compares the incidence of the development of the disease or illness between groups.
What is a “double blind trial”?
A procedure of blind assignment to study and control groups and blind assessment of outcome, designed to prevent bias from knowledge of the group to which individual was assigned.
What is the “ecological fallacy”?
The BIAS that may occur if the associations of a general population are applied to individual cases.
What is a retrospective (sometimes called historical) cohort study?
A study that makes use of pre existing health related facts about members of a defined population who can be classified into exposed or non exposed groups based on factors that may have been experienced decades earlier.
What is information bias?
Systematic error due to differences in the quality of information obtained from different groups in a study.
What is a randomised control trial?
An EXPERIMENTAL study in which subjects in a population are randomly allocated into groups, to receive or not receive an experimental procedure or therapeutic procedure. Most scientifically rigorous method of hypothesis testing available in epidemiology.
What is “recall bias”?
A systematic error that is caused by differing degrees of accuracy in remembering past events. i.e. past medical history
What may cause Osmotic Diarrhoea?
Lactose intolerance
IBS
Toddler Diarrhoea
Laxative
Which inflmmatory bowell disorders may cause diarrhoea?
IBS
Crohn’s
Ulcerative collitis
A well woman with episodic diarrhoea lives a very stressful life, and does not eat well or regularly. What is your preliminary diagnosis?
IBS
Toddler with acute watery diarrhoea. Likely caused by?
Rotavirus
Usual antibiotic treatment for dysentry?
Ciprofloxacin or other fluoro quinolones
Child with angular stomatitis, peri anal ulceration, cold peripheries and a 6 day history of diarrhoea. What underlying condition do you suspect?
AD with SAM
