Gi infections Flashcards
What are 3 examples of good bacterial flora?
- Bifidobacteria
- Escherichia coli
- Lactobacilli
What are 3 examples of bad bacterial flora?
- Campylobacter
- Enterococcus faecalis
- Clostridium Difficile
What are 3 causative agents of GI infections?
- Bacteria
- Viruses (most common)
- Protozoa
What % of duodenal ulcers are associated with Helicobacter pylori?
90%
What % of gastric ulcers are associated with Helicobacter pylori?
70-80%
Which microorganism increases the risk of gastric ulcers which can lead to an adenocarcinoma?
Helicobacter pylori
The mode of transfer of helicobacter pylori is undefined. What is the transmission probably from?
- Probably faecal-oral route
- Oral-oral route also implicated
How is the acid tolerance of Helicobacter pylori critical for the diagnosis of it?
As it can turn acid into ammonia which detoxifies the acid
Ammonia is typical of the breath test
- Causes smell on breath - diagnostic
What are 3 ways of diagnosing if someone has helicobacter pylori?
- Endoscopy & biopsy
- Breath test
- Serology
What are the possible treatment options for someone with helicobacter pylori? (3 points)
- Proton pump inhibitor
- Bismuth salts
- Antibiotics (amoxicillin, clarithromycin
- Metronidazole
What is gastroenteritis?
A non-specific term for various pathological states of the GI tract
- The primary manifestation is diarrhoea, but it may be accompanied by nausea, vomiting and abdominal pain
A universal definition of diarrhoea does not exist? what do definitions centre on?
- Frequency, consistency and a high water content
- Disease of the small intestine and involving increased fluid and electrolyt e loss
What are key symptoms of viral gastroenteritis? (6 points)
- Abdominal cramps (No.1)
- Vomiting
- Profuse watery stools
- Myalgias
- Fever
- Headache
What is myalgias?
- Muscle pain
What are the key symptoms of bacterial dysentery gastroenteritis? (5 points)
- Small volume stools
- Fever
- Tenesmus
- Bloody mucoid stools
- Suprapubic pain
What is tenesmus?
Cramping rectal pain - gives you the feeling that you need to have a bowel movement even if you have already had one
What % of GI infections are viral?
50-70%
What % of GI infections are bacterial?
- 15-20%
What % of GI infections are parasitic?
10-15%
What are examples of viruses that can cause GI infections? (6 points)
- Norovirus
- Calicivirus
- Rotavirus
- Adenovirus
- Parvovirus
- Astrovirus
What are examples of bacteria that cause GI infections? (3 points)
- Salmonella
- Shigella
- Campylobacter species
What are examples of parasites that cause GI infections? (3 points)
- Giardia lambila
- Entamoeba
- Cryptosporidium
What is an invasive infection?
The organism enters the mucosal cells, destroys them, causing diarrhoea usually with blood in the stool
What are enterotoxic syndromes?
The organisms do not invade the mucosa, but produce enterotoxins of which act as chemical mediators causing hypersecretion of the fluid. Little damage to the tissue is done
What is the norovirus?
A non-enveloped SS RNA virus (caliciviridae)
How is the norovirus transmitted?
Via faecal-oral route
How many particles of the norovirus are needed for infection?
only 10-100
Is the norovirus highly contagious?
YES
What is the incubation period for the norovirus?
~ 1-2 days
What are the clinical features of the norovirus?
Abrupt onset of vomiting & watery diarrhoea +/- fever and abdominal pain (similar to rotavirus)
How do you manage the norovirus?
Self-limiting = Correct fluid/ electrolyte balance
Is the norovirus resilient in the environment?
Yes
What is the norovirus a recurrent infection?
It is strain specific so immunity only lasts a few months. Repeated infections
How is salmonella transmitted?
It is food borne
What are the 3 types of salmonella?
- Gastroenteritis is the most common form
- Enteric fever - Typhoid fever
- Bacteremia
(eating foods produces from infected animals; meat, milk, poultry, eggs, and drinking contaminated water; and from faecal-oral trans)
What is the incubation period for salmonella?
8-48hrs
What are the symptoms of salmonella? (3 points)
Asymptomatic or symptoms develop within 2 days of eating infected food:
- Watery or bloody diarrhoea
- Fever and sometimes vomiting
- Cramps
How long do symptoms of salmonella last?
1-4 days
How would you diagnose salmonella?
- Stool
- Presence of faecal WBC’s variable
How would you treat salmonella?
- Supportive (IV hydration)
- Antibiotics usually not necessary for salmonella gastroenteritis
What is a common cause of antibiotic-associated diarrhoea?
Clostridium difficile
What is the only nosocomial organism that is anaerobic and forms spores (survive > 5 months and are hard to destroy)?
Clostridium difficile
What is the pathogenesis of clostridium difficile mainly due to?
- Mainly due to toxins production
What is the infective dose of clostridium difficile?
<10 spores
What are risk factors of clostridium difficile? (9 points)
- Exposure to antimicrobials
- Exposure to healthcare
- Infection with toxic strains of C. difficile
- Old age > 64
- Underlying illness
- Immunosuppression & HIV
- Chemotherapy (immunosuppression & antibiotic-like activities)
- Tube feeds and GI surgery
- Exposure to gastric acid suppression meds
What is C. difficile?
Gram positive spore forming bacillus (rods)
C. difficile is an obligate anaerobe. What does this mean?
Can only grow in the complete absence of O2
C. difficile is part of the GI flora in what % of healthy adults?
1-3%
C. difficile is part of the GI flora in what % of children < 12 months?
70%
Some strains of C. difficile produce toxins. What toxins do they produce?
Toxins A & B
What is the mortality rate of C. difficile?
35%
How can C. difficile be transmitted? (3 points)
Faecal-oral route
- Contaminated hands of healthcare workers
- Contaminated environmental surfaces
Person to person in hospitals
Reservoir
- Human: colonized or infected persons
- Contaminated environment
How long can C. difficile spores survive on environmental surface?
For up to 5 months
What are the 3 possible stages of C. difficile?
- Asymptomatic carriers = colonised
- Mild or moderate diarrhoea
- Pseudo membranous colitis that can be fatal
What is the general incubation period of C. difficile?
2-3 days
What are the common symptoms of C. difficile infection?
- Watery diarrhoea
- Loss of appetite
- Fever
- Nausea
- Abdominal pain and cramping
What % of hospitalised patients are colonised with C. difficile?
20%
What are antibiotics that are very commonly related to C. difficile? (5 points)
- Clindamycin
- Ampicillin
- Amoxycillin
- Cephalosporin
- Fluoroquinolones
What are antibiotics that are less commonly related to C. difficile? (4 points)
- Sulfa
- Macrolides
- Carbapenems
- Other penicillin’s
What are antibiotics that are uncommonly related to C. difficile? (4 points)
- Aminoglycsides
- Rifampin
- Tetracycline
- Chloramphincol
What is the treatment of C. Difficile? (5 points)
- Oral rehydration
- Antibiotics (Metronidazole, Vancomycin)
- Probiotics
- Colectomy
- Faecal transplants
What are ways of preventing GI infections? (4 points)
- Use of statutory powers
- Safe food handling & hand washing
- Infection control - enteric precautions for diarrhoea & vomiting
- Surveillance
