GI Infections Flashcards
What is an example of a bacterial GI infection?
vibrio cholera
c. difficle
What is an example of a viral GI infection?
norovirus
What is an example of a fungal GI infection?
mycotoxins (alflatoxins)
What is an example of a parasite GI infection?
protozoan (cryptosporidium)
What is an example of a prion GI infection?
BSE
What is cholera?
acute diarrhoeal infection associated with inadequate access to safe water and basic sanitation
Why is norovirus difficult?
extremely tolerant, persistant, large genetic variety and contagious
What type of virus is norovirus?
RNA non-enveloped virus
What are aflatoxins produced by?
moulds such as aspergilius flavus
Why are aflatoxins bad?
high toxicity for humans
acute hepatitis and liver cancer
What feature of cryptosporidium aids survival?
prevalent watterborne disease with outbreaks worldwide
life cycle involves thick walled oocysts which survive
for several months in environment
What is the neural consequence of BSE?
degeneration of brain tissue =
sponge-like appearance leading to death
What is a prion?
an abnormal form of
a normal body protein that has no RNA/DNA
What is human variant of BSE?
vCJD via meat
What is the impact of C. difficile on patients?
- Pts suffer & get harmed unnecessarily by the spread of C. difficile
- C. difficile is the most common bacterial cause of HAI GI infection in adults
- CDI and outbreaks = mild diarrhoea to life threatening colitis Colitis = 5-10% mortality rate
Where did C.difficile decrease instead of rates staying constant?
community associated infections
What is the chain of infection for C.difficile?
Pathogen: Bacteria and bacterial spores
Reservoir: GIT, food
Portal of exit: faeces
Means of transmission: Faecal-oral (spores)
Portal of entry: oral
Susceptible hosts: Prior antibiotic therapy, elderly, hospitalized, prior C. diff, immunocompromised
What are the characteristics of the bacteria c.difficile?
gram positive anaerobic bacillus
spore forming (germination)
two exotoxins (A & B)
What do the two exotoxins cause?
necrosis of intestinal epithelial cells, infiltration of neutrophils and a outpouring of fluid into the intestinal lumen
What antibiotic used of CDI may be dentally relavant?
clindamycin
used for bone infections
What must happen to get a CDI?
The bowel flora must be altered
The bowel must be colonized with a toxigenic strain
The organism must grow and produce toxins
What does C.difficile form on the surface of the colon mucosa?
pseudomembrane = false membrane consisting of a layer of exudate on the surface of a mucosa/ skin membrane
In which age group are carriage rates high in CD?
newborns and infants under two years
What is the reservior of C.difficile?
GIT, food
found in the IT of many types of food animals, dogs and cats
How does C.difficile transmit?
via tolerant spores through faecal oral route and contact (also through contact with contaminated equipment or environment)
What are the characteristics of spores?
tolerant to antiseptics, high survival
main mode of transmission
When is there an increased risk of CDI? (susceptibile hosts)
Current or recent (3 months) use of broad spectrum antibiotic
Prolonged hospital stay/ Surgical procedures (esp bowel)
Elderly
Use of PPIs
Serious underlying diseases/ Immunosuppression (HIV infection and transplant)
What is the recurrence rate of CDI?
20%
How can re-infection occur?
from contaminated environment or poor hand hygiene
Or
relapse from germinating spores in the gut
What is recurrence associated with?
significant increase of death
What is an intervention for c.diffcile at the reservoir part of the chain?
review antibiotic use
(antimicrobial stewardship- antibiotics can cause CDI )
When are antibitoics not recommened for dentistry?
dental cleaning for patients that can clean
prophylaxis for oral surgery
When can symptoms occur after discontinuation of antibiotic treatment?
up to 8 weeks
What are general principles used in hospitals to intervene at transmission stage?
- Isolation
- Perform hand hygiene (soap & water)
- Decontaminate equipment and environment
How to decrease portal of entry?
use PPE
perform good hand hygiene
What are the principles that should be used for dental practice?
standard infection control precautions guidelines
How to intervene at susceptible host stage?
recognise high risk patients (medical history)
consider patient placement
What is an example of a occupational health issue concerning attendance?
presenteeism
turning up to work when too unwell, and fatigued to be productive.
When do symptoms present in norovirus?
12-48 hours
When is norovirus most infectious?
Most infectious when symptomatic,
but it is possible to pass on norovirus or shed the virus, Immediately prior to & after symptoms
What is occuptational health advice for norovirus?
Alcohol-based hand sanitisers are not effective against norovirus.
Stay at home.
Do not return to work until 48 hours after the symptoms have stopped.
