Gastroenteritis Flashcards
What is the commonest cause of GASTROENTERITIS?
Campylobacter
What bacteria cause OUTBREAKS of GASTROENTERITIS?
Salmonella and E coli 0157
E coli is rare but has high morbidity
Which bacteria can be invasive (cause bacteremia and sepsis) in immunosupressed patients?
Campylobacter and Salmonella
What is incubation?
Period between first exposure to pathogen and appearance of symptoms
Which bacteria have SHORT intubation periods? (1-6hrs)
Staph aureous: preoformed EMETOGENIC toxin in food
Bacillus cereus: Heat resistant spores, bacterial growth results in production of EMETOGENIC toxins
EMETOGENIC TOXINS STIMULAT VOMITING CENTRE AND FAST!
Which bacteria causes “fried rice syndrome”?
bacillus cereus
T/f
Bacillus cereus will present with lower GI tract symptoms (cramps, diarrhea) then upper GI tract symptoms (nausea vomiting)
F
other way round
EMETOGENIC TOXIN PRODUCER!
T/F
Toxins simulate outpouring of fluid into bowel lumen due to inflammatory processes
T
Bacteria with medium incubation periods? (12-48hrs)
Salmonella
These invade the gut and cause mucosal daamage via ulceration and inflammation.
bloody diarrhea
Bacteria with long incubation periods? (2-14 days)
Campylobacter
E coli 1057
These INVADE the gut and cause mucosal daamage via ulceration and inflammation.
bloody diarrhea
Where is campylobcter found/how does it spread?
food hygiene (raw poultry especially)
less likely to spread person to person
How does campylobacter present?
cramps, bloody diarrhea/dysentry (30%), fever, pain
What type of bacteria is campylobacter?
spirillum with bi polar flagella
What is the structure of salmonellla
Lipopolysachharide (endotoxins)
Antigens on cell wall (O antigens)
Antigens on flagellum (H antigens)
How to treat campylobacter?
Macrolide (clarithromycin, erythromycin)
Transmission salmonella?
poultry, meat, raw egg
animal gut, multiplies in food
Why does gastroenteritis cause vomiting?
- EMETOGENIC toxins such as from staph aureous and bacillus cerus, absorbed systemically and stimulate vomiting centre. (emesis=vomiting)
- Toxins cause inflammation which leads to
1. Distension and mucosal damage which stimulates efferent nerves to vomit
Why does gastroenteritis cause diarrhea?
- ENTEROTOXINS (enterotoxigenic e coli 1507) drive excessive intestinal secretion
- Inflammation reduces digestive ability which increases osmotic load (watery diarrhea)
- inflammation leads to build up of exudate fluid & cells (inc. vasopermeability)
Why is serotyping significant in salmonella?
Serotyping is looking at stuff on pathogen surface (serology antibodies)
Help to pinpoint infection (whether local or abroad)
Typhoidal or non typhoidal?
What are the toxins produced by E coli 01507 called?
Shiga-like toxins, functionally simmular to shigella toxins
Lab tests for typing e coli?
Maconkey Agar
Antisera: Serum with antibodies - detect which ones bind to which antigen (01507 antigen)
ELISA Enzyme autoimmunessay
DNA of toxin genes
How does Maconkey agar show presence of E coli?
Lactose fermentation - enteric bacteria can do this
Transmission e coli?
LOW infectious does
Food
Person to person
drinking water contaminated with faeces
Complications/presentation of SHIGA LIKE TOXIN PRODUCING E coli?
Bloody diarrhea
Haemorrhagic colitis - invades submucosa LOTS inflammation, SEVERE CRAMPING and super bloody diarrhea
Haemolytic Uraemic Syndrome - anaemia and kidney failure
What does shiga-like toxin do?
Binds to receptors on renal cells, RBCs and others
Inhibit protein synthesis - cell death
CAUSES HAEMOLYTIC URAEMIC SYNDROME!!!!!
T/F
Rotavirus outbreaks more common in the summertime
F
MORE COMMON IN WINTER
Rotavirus spread?
Contaminated water and food
faecal oral
Fomites - objects that can carry the virus i.e. telephone, water play tables in day-care nurseries
T/F
all kids get rotavirus before age 5
T
Presentation rotavirus
Acute onset vomiting& FEVER
followed by frequent NON BLOODY DIARRHOEA
Diagnosis rotavirus?
PCR faeces
billions shed in faeces
Norovirus spread?
Contaminated water and food
faecal oral
Fomites - objects that can carry the virus i.e. telephone, water play tables in day-care nurseries
Which virus causes outbreaks nursing homes, hospitals, cruise ships, leisure centres etc?
NOROVIRUS
Rotavirus also has low infectious dose and transmission pathways but more associated with infants!
Which virus is characterized by sudden explosive diarrhea and vomiting?
NOROVIRUS!
T/F
Norovirus has asymptomatic shedding 48hrs post symptoms
T
Rotavirus has post infective what?
Malabsorption
Diagnose norovirus?
PCR stool 6hrs
PCR vomit using red copan viral swabs
Presentation norovirus?
Nausea, vomiting, cramping, diarrhea non bloody, fever, myalgia, headache
Non typhi salmonella presentation?
Diarrhea, fever, abdominal cramps, vomiting
Presentation of entertoxigenic E coli?
NOT SHIGA LIKE TOXIN PROD
watery diarrhea, cramps, some vomiting
