Infections of the Gastrointestinal Tract Flashcards
What areas of the GI tract are usually mostly sterile?
Stomach and small intestine
What % of the immune system is in the gut?
80%
Where are normal microbiotia confined to?
Mouth and large intestines
What are the types of foodborne diseases?
Food Poisoning and food infection
What is food poisoning?
Disease that results from ingestion of foods containing preformed microbial toxins. The microorganisms that produced the toxins do not have to grow in the host
What is food infection?
microbial infection resulting from the ingestion of pathogen-contaminated food followed by growth of pathogen in the host
What type of foodborne disease is clostridium perfringens and clostridium botulinum and what do they produce?
clostridial food poisoning.- can cause paralysis. Produce exotoxin, botulinum toxin, and tough endospores that are hard to kill.
How is clostridium difficile transmitted?
Person to person by the fecal-oral route.
How is c.difficile hard to kill?
Forms heat resistant spores, aren’t killed by alcohol-based cleanser or routine cleaning and survive for long periods of time.
Once c.diff is ingested
Acid-resistance allows them to ass through stomach and upon exposure to bile acids they germinate and multiply into cells in the colon.
Why can’t antibiotics not be used to treat c.diff?
Antibiotics disrupt the normal intestinal flora which can lead to an overgrowth of c.diff as it flourishes under these conditions
What is colitis associated with severe infection?
Pseudomembranous colitis is the inflammation of the large intestines/colon. Part of an inflammatory reaction with the pseudomembrane formed by a viscous collection of inflammatory cells, fibrin and necrotic cells.
What is the only affective treatment for c.diff?
Faecal transplants
What is salmonellosis?
A gastrointestinal illness caused by foodborne salmonella infection= food infection.
How is salmonella caused?
Caused by eating food contaminated with Salmonella or handling salmonella-infected animals.
How does salmonella act once ingested?
Invades phagocytes and grows as an intracellular pathogen.
Salmonella bacteria are
gram negative rod-shaped facultative anaerobe (flagellated), which cause enterocolitis, enteric fevers and septicaemia
What is enterocolitis?
Invasion between mucosal cells causing inflammation and diarrhoea.
What are the two categories of salmonellae?
- Typhoidal species
- Non-typhoidal or enterocolitis species
What us typhoid
An enteric fever caused by infection with salmonella enterica serotype typhi
How is S. typhi transmitted?
Through faecal oral route (food, water). Humans are the only reservoir for it. People can be chronic asymptomatic carriers posing risk to others, particularly in preparing food
How can S.typhi be prevented?
Vaccine
First week classic clincal features of typhoid fever
stepwise rising fever, bacteremia
Second week classic clinical features of typhoid fever
abdo pain and “rose spots” on trunk and abdo
Third week classic clinical features of typhoid fever
liver and spleen inflammation, intestinal bleeding, peritonitis, septic shock and death
Widal test for O antigens of different strains of Salmonella enterica will show what on positive and negative tests?
Postive: Agglutination within a minute
Negative test: No agglutination
Treatment of Salmonella
Fluroqinolones, 3rd generation cephalosporins such as ceftriaxone, azithromycin.
What attributes do noroviruses have that makes them an ideal infectious agents?
High contagious, rapidly and prolifically shed, constantly evolving (changes its genome), evoking limited immunity, and only moderately virulent.
Why is norovirus so contagious? How many copies of norovirus on average does it take to get sick?
Little amount of copies of the virus are need to make a person sick. Approx. 9 copies.
What type of virus is norovirus? what is its genetic material?
RNA virus. Calicivirus- known for being very infectious
How is norovirus transmitted?
droplet, contact with faeces or vomit. Vomiting is the most efficient way to spread to virus.
How is the causative agent of gastroenteritis diagnosed?
Stool sample- PCR (RTPCR), culture on agar & symptoms
What puts you at risk of getting norovirus?
Living in close proximity to others, and being immunocompromised
What treatment should be given for norovirus?
Fluids
How to prevent norovirus?
Isolate infected individuals, barrier nursing, hand hygiene, food hygiene, and stay away from work for 48 hours.
