30 Questions
Which of the following bacteria is not typically associated with inflammatory gastrointestinal infections?
Helicobacter pylori
Which of the following bacteria is commonly associated with food poisoning?
Bacillus cereus
Which of the following is not a type of E. coli?
Listeria monocytogenes
Which of the following bacteria is associated with gastritis and ulcers?
Helicobacter pylori
Which of the following bacteria is typically associated with inflammatory gastrointestinal infections?
Listeria monocytogenes
Which of the following bacteria is commonly associated with cholera?
Vibrio cholerae
Which type of E. coli causes a non-inflammatory response in the gut?
Enteropathogenic E. coli
What is the primary mechanism of pathogenesis for Staphylococcus aureus in bacterial food poisoning?
Ingestion of preformed staphylococcal enterotoxins
Which of the following bacteria is NOT associated with inflammatory responses in the gut?
Enteropathogenic E. coli
What is the typical duration of symptoms for bacterial food poisoning caused by Staphylococcus aureus?
24-48 hours
Which of the following bacteria produces heat-labile toxins?
None of the above
What is the primary treatment for bacterial food poisoning caused by Staphylococcus aureus?
Supportive therapy
What is the primary animal reservoir for Enterohemorrhagic E. coli (EHEC)?
Cattle or other ruminants
Which of the following is NOT a characteristic of Enterohemorrhagic E. coli (EHEC)?
Gram-positive
What is the most common serotype of Enterohemorrhagic E. coli (EHEC) associated with severe disease in the US?
O157:H7
Which of the following foods is most commonly associated with outbreaks of Enterohemorrhagic E. coli (EHEC)?
Ground beef
What is the alternative name for Enterohemorrhagic E. coli (EHEC)?
STEC (Shiga toxin E. coli)
What is the primary mode of transmission of Enterohemorrhagic E. coli (EHEC)?
Contaminated food
What is the primary reservoir for Salmonella Typhi?
Humans
What is the approximate number of cases of Salmonella Typhi per year worldwide?
11-20 million
What is the mechanism of transmission of Salmonella Typhi?
Fecal-oral transmission
What is the characteristic of the flagella of Salmonella Typhi?
H antigen
What is the approximate incubation period of Salmonella Typhi?
13 days
What is the possible outcome of Salmonella Typhi infection in the gall bladder?
Chronic colonization
What is the primary factor that increases the likelihood of developing C. diff disease by 7-10 times?
Recent antibiotic use
Which test is commonly used for diagnosing C. diff infections, but is less sensitive and has a limitation?
EIA test for toxin A, toxin B, or both in stool, but it is affected by temperature
What is the minimum number of loose stools in 24 hours required for testing for C. diff in patients with risk factors?
3
Which of the following is a risk factor for developing C. diff disease, but is not a consequence of the disease?
Weakened immune system
What is the purpose of using multiple diagnostic testing algorithms for C. diff infections?
To increase the confidence in the diagnosis
Which of the following is a characteristic of C. diff infections that can be used for diagnosis?
Presence of toxin A or toxin B in stool
Study Notes
Bacterial GI Infections
- Bacterial food poisoning can be caused by:
- Staphylococcus aureus
- Clostridium botulinum
- Clostridium perfringens
- Bacillus cereus
- Gastritis/Ulcers: Helicobacter pylori
- Non-inflammatory: Enteropathogenic E. coli, Enterotoxigenic E. coli, Vibrio cholerae
- Inflammatory-ish: Listeria monocytogenes
- Inflammatory: Enterohemorrhagic E. coli, Salmonella Typhi, Nontyphoidal Salmonella, Campylobacter jejuni, Vibrio parahaemolyticus, Yersinia enterocolitica, Clostridioides difficile, Shigella spp., Enteroinvasive E. coli
Staphylococcus aureus
- Causes severe vomiting, diarrhea, and abdominal pain within 1-8 hours post consumption
- Resolves in ~24 hours
- Pathogenesis: Ingestion of preformed staphylococcal enterotoxins
- Enterotoxin A to Z, with enterotoxin A being the most common
- All are heat-stable toxins that survive cooking and reheating
Clostridioides difficile
- Risk factors for developing C. diff disease:
- Recent antibiotic use (7-10x more likely)
- Extended stays in healthcare settings
- ≥ 65 years old
- Weakened immune system
- Previous C. diff infection
- Known C. diff exposure
- Diagnosis: Test for C. diff in patients with ≥ 3 loose stools in 24 hours with risk factors
- Multiple diagnostic testing algorithms are used, with at least 2 testing modalities
- Tests: EIA test for toxin A, toxin B, or both in stool
Enterohemorrhagic E. coli (EHEC)
- Characteristics:
- Gram-negative, facultative anaerobe
- Also known as STEC (Shiga toxin E. coli)
- Several serotypes, with O157:H7 causing 50% of severe disease in the US
- Animal reservoirs: cattle or other ruminants
- Generally non-invasive
- Epidemiology:
- Sporadic cases and outbreaks mainly in the developed world
- Associated with contaminated: ground beef, raw vegetables or fruit, and washed with water from rivers/streams
Salmonella Typhi
- Characteristics:
- Gram-negative, facultative anaerobe
- Motile rods, flagellated (H antigen)
- Intracellular pathogen
- Highly adapted to humans
- Epidemiology:
- Humans are the only reservoir
- 400-500 cases per year in the US (80% associated with travel to endemic areas)
- Endemic in developing areas of Africa, the Americas, South-East Asia, and the Western Pacific regions
- 11-20 million cases per year, with ~150,000 deaths worldwide
- Fecal-oral transmission: contaminated food/water from infected person
- Infectious dose: 10^5 - 10^6 bacteria
- Clinical manifestation:
- ~13 day incubation
- Symptom progression: fever with headache, rising fever over 3 days, typhoid (enteric) fever, prolonged fever (~4 weeks)
- Infection of the gallbladder, potentially leading to chronic colonization of the gallbladder and shedding of Salmonella
Test your knowledge on bacterial infections affecting the gastrointestinal system, including food poisoning caused by Staphylococcus aureus, Clostridium botulinum, and more. Learn about the different types of E. coli and their effects on the body. Understand the impact of COVID-19 on GI diseases.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
