Podcast
Questions and Answers
Which virulence factor of H. pylori enables it to penetrate the protective mucous layer of the stomach?
Which virulence factor of H. pylori enables it to penetrate the protective mucous layer of the stomach?
What is the primary role of urease in the pathogenesis of H. pylori infection?
What is the primary role of urease in the pathogenesis of H. pylori infection?
Which H. pylori virulence factor is associated with a pathogenicity island containing approximately 30 genes?
Which H. pylori virulence factor is associated with a pathogenicity island containing approximately 30 genes?
What is the purpose of the radiolabeled urea in the urea breath test for H. pylori?
What is the purpose of the radiolabeled urea in the urea breath test for H. pylori?
Signup and view all the answers
A patient has a positive stool antigen test for H. pylori. What does this result primarily indicate?
A patient has a positive stool antigen test for H. pylori. What does this result primarily indicate?
Signup and view all the answers
In the case report, what was the primary reason for the failure of the initial 14-day course of clarithromycin triple therapy?
In the case report, what was the primary reason for the failure of the initial 14-day course of clarithromycin triple therapy?
Signup and view all the answers
What is the significance of detecting IgG antibodies in serum when testing for H. pylori?
What is the significance of detecting IgG antibodies in serum when testing for H. pylori?
Signup and view all the answers
Which of the following best describes the role of a biopsy in the context of H. pylori diagnosis?
Which of the following best describes the role of a biopsy in the context of H. pylori diagnosis?
Signup and view all the answers
Which viral family is associated with a 'wheel shaped' virus?
Which viral family is associated with a 'wheel shaped' virus?
Signup and view all the answers
Which of the following viruses has a double-stranded DNA genome?
Which of the following viruses has a double-stranded DNA genome?
Signup and view all the answers
Which of the listed viruses is known to have a segmented genome?
Which of the listed viruses is known to have a segmented genome?
Signup and view all the answers
Which of the following is a characteristic of the capsid shape of all the viruses listed?
Which of the following is a characteristic of the capsid shape of all the viruses listed?
Signup and view all the answers
Which virus that causes diarrhea has a vaccine available?
Which virus that causes diarrhea has a vaccine available?
Signup and view all the answers
Based on the information provided, which type of bacteria is MOST likely to cause a 'preformed toxin' type of food poisoning?
Based on the information provided, which type of bacteria is MOST likely to cause a 'preformed toxin' type of food poisoning?
Signup and view all the answers
If a patient has 'inflammatory diarrhea,' which of the following bacteria from the list is LEAST likely to be the cause?
If a patient has 'inflammatory diarrhea,' which of the following bacteria from the list is LEAST likely to be the cause?
Signup and view all the answers
Based on the patient's travel history and the onset of symptoms during the airplane flight, which of the following viral infections is MOST likely responsible for her symptoms?
Based on the patient's travel history and the onset of symptoms during the airplane flight, which of the following viral infections is MOST likely responsible for her symptoms?
Signup and view all the answers
Which characteristic is associated with Salmonella enterica?
Which characteristic is associated with Salmonella enterica?
Signup and view all the answers
In cases of severe typhoid fever in adults, which antibiotic is most suitable for treatment?
In cases of severe typhoid fever in adults, which antibiotic is most suitable for treatment?
Signup and view all the answers
Which of the following is a common animal reservoir for Yersinia enterocolitica?
Which of the following is a common animal reservoir for Yersinia enterocolitica?
Signup and view all the answers
Which of the following describes the typical clinical course of Yersinia enterocolitica infection?
Which of the following describes the typical clinical course of Yersinia enterocolitica infection?
Signup and view all the answers
What is a key characteristic of a bacterial infection that causes 'preformed toxin food poisoning'?
What is a key characteristic of a bacterial infection that causes 'preformed toxin food poisoning'?
Signup and view all the answers
Which of these bacteria is associated with black colonies on SS or Hektoen agar?
Which of these bacteria is associated with black colonies on SS or Hektoen agar?
Signup and view all the answers
A child is diagnosed with typhoid, what is the recommended antibiotic to treat this?
A child is diagnosed with typhoid, what is the recommended antibiotic to treat this?
Signup and view all the answers
Besides meat, which food item is recognized as a common source of Yersinia enterocolitica?
Besides meat, which food item is recognized as a common source of Yersinia enterocolitica?
Signup and view all the answers
Which characteristic is NOT associated with Listeria monocytogenes?
Which characteristic is NOT associated with Listeria monocytogenes?
Signup and view all the answers
A pregnant woman is diagnosed with listeriosis. What is the most critical concern regarding the fetus?
A pregnant woman is diagnosed with listeriosis. What is the most critical concern regarding the fetus?
Signup and view all the answers
In which patient population is dissemination of Listeria bacteria most likely to occur, leading to bacteremia or meningoencephalitis?
In which patient population is dissemination of Listeria bacteria most likely to occur, leading to bacteremia or meningoencephalitis?
Signup and view all the answers
What is the primary mechanism by which Listeria monocytogenes escapes the phagosome?
What is the primary mechanism by which Listeria monocytogenes escapes the phagosome?
Signup and view all the answers
A blood culture from a 29-week pregnant woman shows Gram-positive rods. What is the MOST likely cause of her symptoms, which included vaginal bleeding, abdominal pain, and fever?
A blood culture from a 29-week pregnant woman shows Gram-positive rods. What is the MOST likely cause of her symptoms, which included vaginal bleeding, abdominal pain, and fever?
Signup and view all the answers
What is the recommended initial antibiotic treatment for a patient with mild symptoms of listeriosis?
What is the recommended initial antibiotic treatment for a patient with mild symptoms of listeriosis?
Signup and view all the answers
Which food source is NOT specifically associated with Listeria contamination?
Which food source is NOT specifically associated with Listeria contamination?
Signup and view all the answers
What is a key characteristic of Tropheryma whipplei that makes it difficult to identify using traditional methods?
What is a key characteristic of Tropheryma whipplei that makes it difficult to identify using traditional methods?
Signup and view all the answers
Which of the following conditions is NOT typically associated with Listeria monocytogenes infection?
Which of the following conditions is NOT typically associated with Listeria monocytogenes infection?
Signup and view all the answers
What temperature is associated with the motility of Listeria monocytogenes?
What temperature is associated with the motility of Listeria monocytogenes?
Signup and view all the answers
A patient presents with watery, non-bloody diarrhea with minimal vomiting, and is afebrile. A stool culture grows lactose-fermenting colonies on EMB agar. Which of the following is the most likely causative agent?
A patient presents with watery, non-bloody diarrhea with minimal vomiting, and is afebrile. A stool culture grows lactose-fermenting colonies on EMB agar. Which of the following is the most likely causative agent?
Signup and view all the answers
A patient treated with ampicillin for cellulitis develops bloody diarrhea and pseudomembranous plaques in the colon. Which of the following best describes the most likely pathogen?
A patient treated with ampicillin for cellulitis develops bloody diarrhea and pseudomembranous plaques in the colon. Which of the following best describes the most likely pathogen?
Signup and view all the answers
A 3-year-old child at a daycare develops fever, vomiting, and bloody diarrhea with mucus and pus. They have significant weight loss and dehydration. Which of the following is the most likely cause?
A 3-year-old child at a daycare develops fever, vomiting, and bloody diarrhea with mucus and pus. They have significant weight loss and dehydration. Which of the following is the most likely cause?
Signup and view all the answers
Which of the following is a key differentiating factor between ETEC and Shigella sonnei in a patient with diarrhea?
Which of the following is a key differentiating factor between ETEC and Shigella sonnei in a patient with diarrhea?
Signup and view all the answers
A patient develops pseudomembranous colitis after antibiotic treatment. What is the primary mechanism by which the causative agent induces colonic damage in humans?
A patient develops pseudomembranous colitis after antibiotic treatment. What is the primary mechanism by which the causative agent induces colonic damage in humans?
Signup and view all the answers
A patient presents to the emergency department with severe dehydration, fever, and bloody diarrhea, consistent with invasive infection. What type of bacteria is most likely responsible?
A patient presents to the emergency department with severe dehydration, fever, and bloody diarrhea, consistent with invasive infection. What type of bacteria is most likely responsible?
Signup and view all the answers
A 3-year-old child presents with a recent history of vomiting and diarrheoa. Their current symptoms includes a fever, bloody diarrhea, and high pulse rate. Which of the following conditions is a key factor in the pathogenesis of this patients symptoms?
A 3-year-old child presents with a recent history of vomiting and diarrheoa. Their current symptoms includes a fever, bloody diarrhea, and high pulse rate. Which of the following conditions is a key factor in the pathogenesis of this patients symptoms?
Signup and view all the answers
What critical step should be taken first when dealing with a patient presenting with bloody diarrhea and dehydration?
What critical step should be taken first when dealing with a patient presenting with bloody diarrhea and dehydration?
Signup and view all the answers
Which host defense mechanism is most critical in preventing dysentery caused by Salmonella?
Which host defense mechanism is most critical in preventing dysentery caused by Salmonella?
Signup and view all the answers
Which pathogen is known for having the lowest 50% infectious dose (ID50)?
Which pathogen is known for having the lowest 50% infectious dose (ID50)?
Signup and view all the answers
Which GI tract pathogen is most likely to cause bacteremia?
Which GI tract pathogen is most likely to cause bacteremia?
Signup and view all the answers
A 3-year-old at a daycare presents with fever, vomiting, diarrhea with mucus, blood, and pus in the stool. Which pathogen is the most likely cause?
A 3-year-old at a daycare presents with fever, vomiting, diarrhea with mucus, blood, and pus in the stool. Which pathogen is the most likely cause?
Signup and view all the answers
A patient treated with ampicillin develops bloody diarrhea and pseudomembranous colitis. Which of the following best describes the most likely pathogen?
A patient treated with ampicillin develops bloody diarrhea and pseudomembranous colitis. Which of the following best describes the most likely pathogen?
Signup and view all the answers
A previously healthy 45-year-old is brought to the ER due to fever and bloody diarrhea over the past 3 days following a company barbecue. Which of the following is the most likely cause?
A previously healthy 45-year-old is brought to the ER due to fever and bloody diarrhea over the past 3 days following a company barbecue. Which of the following is the most likely cause?
Signup and view all the answers
Which of the following pathogens from the content is most associated with outbreaks in daycare settings?
Which of the following pathogens from the content is most associated with outbreaks in daycare settings?
Signup and view all the answers
Which of the following conditions is characterized by the formation of pseudomembranous plaques in the colon?
Which of the following conditions is characterized by the formation of pseudomembranous plaques in the colon?
Signup and view all the answers
Study Notes
GI Pathogens: Bacteria and Viruses
- This presentation covers GI pathogens, including bacteria and viruses.
- A humorous image is included, highlighting laughter not being the best medicine for diarrhea.
- Dr. Steinauer declares no financial interests or conflicts of interest.
Learning Objectives
- Understand pathogen transmission, including reservoirs.
- Know the infectivity needed to establish an infection.
- Learn the factors that increase infection risk.
- Understand the course of infection, including where the pathogen establishes and if it stays localized or spreads.
- Know the virulence factors used for establishment, immune avoidance, and disease causation.
- Understand the range of signs and symptoms, including common presentations and the clinical course's general timeline.
- Learn diagnostic methods, such as stain characteristics, culturing techniques, and alternative diagnostics.
- Understand treatment and epidemiology, including risk factors and infection geography.
- Learn about prevention strategies.
Suggested Textbook Reading
- Harrison's Chapter 128: Acute Infectious Diarrheal Diseases
- Levinson Review of Medical Microbiology and Immunology (chapters on relevant microbes)
Pathogens
-
Bacteria:
- Preformed toxin "food poisoning" (Staphylococcus aureus, Bacillus cereus, Clostridium perfringens)
- Helicobacter pylori (associated with ulcers and stomach cancers)
- Vibrio (cholerae, parahaemolyticus, vulnificus)
- Escherichia coli (ETEC, EPEC, EAEC, DAEC, AIEC, EHEC, EIEC)
- Shigella
- Salmonella enterica
- Yersinia enterocolitica
- Campylobacter jejuni
- Clostridioides difficile
- Listeria monocytogenes
- Tropheryma whipplei
-
Viruses:
- Norovirus
- Rotavirus
- Adenovirus
- Astrovirus
- Sapovirus
Transmission
- Fecal-oral or vomit-oral (food, water, fomites, insufficient handwashing, insufficient sanitation)
- Animal Reservoirs (domestic livestock, wildlife, direct contact with animals, shellfish [Vibrio parahaemolyticus, vulnificus])
- Environmental Reservoirs (water, Vibrio cholerae, parahaemolyticus, vulnificus)
- Spore formers (Clostridioides difficile, Clostridium perfringens, Bacillus cereus)
Infectious "Syndromes"
- Toxemia food poisoning (ingesting preformed toxins, rapid incubation, short duration)
- Gastritis, ulcers, stomach cancer
- Watery diarrhea (liquid stools, cramping, vomiting, not invasive)
- Inflammatory diarrhea (invasive, large bowel, fever, blood in stool, ulceration of mucosa, painful)
- Chronic GI symptoms (long course, greater than a week, parasites and travel history, bacterial infections, immunocompromised population)
Diagnosis of GI Pathogens
- Culture-based diagnosis
- PCR-based diagnosis
- Gastrointestinal Pathogen Panel (GPP) PCR utilizing Luminex® xTAG®
Pathogen Panel Diagnostics (example data)
- This section includes extensive data from a diagnostic panel. This data is too extensive to extract completely, but represents an example of the type of information contained.
H. pylori
- Cause of chronic gastritis, peptic ulcers, gastric adenocarcinoma, MALT lymphoma.
- Pathogenic in small proportion of carriers.
- Gram-negative, spiral-shaped bacteria. Features include Oxidase positive, Catalase positive, Urease positive, and Motile (flagella).
-
Invasion and Virulence Factors: Mucinase penetrating the mucous layer, Urease neutralizes the acidic environment, Hydrolyzes urea into carbon dioxide and Ammonia. Cytotoxins (several).
- CagA: exotoxin associated with carcinogenic phenotype, occurs on a pathogenicity island.
- VacA: All H. pylori have this exotoxin, but it is variable; subtype S1 and m1 is associated with a carcinogenic phenotype.
- Diagnosis and Treatment: Urea breath test, stool antigen test, IgG antibody test in serum, PCR (stool or biopsy), Endoscopic tests (biopsy and culture, rapid urease test), Treatment based on susceptibility with Triple/quadruple therapy (14 days).
Vibrio (parahaemolyticus and vulnificus)
- Found in warm coastal waters.
- Exposure through ingestion(raw oysters) or wound contact.
- Vibrio vulnificus is more invasive, causing GI and wound infections for dissemination, and septicemia.
- Treatment: V. parahaemolyticus (often self-limiting, vulnerable patients require treatment), V. vulnificus (20-50% mortality rate, aggressive, wound infections, disseminated GI infections, debride necrotic tissues, Intravenous ceftazidime with either a quinolone or tetracycline)
- Resistant V. vulnificus is an increasing problem.
Vibrio cholerae (Cholera)
- Globally important diarrheal disease
- Transmitted through fecal contamination from water or food
- Large dose required for infection (over 10 million virions), sensitive to stomach acid
- Environmental reservoirs (plankton, shellfishes, environmental biofilms)
- Virulence Factors, Toxin co-regulated pili (attach to epithelial cells to aggregate bacteria into microcolonies), Cholera toxin
- Mechanism of Cholera Toxin: Enters cytoplasm, catalyzes ADP-ribosylation of G protein, activates adenylate cyclase, increases adenylate cyclase resulting in cleavage of ATP to cAMP. Activates CFTR, Cl- and HCO3- secretion, and Na flux of water.
Clinical Course (examples)
- Sections include various clinical courses for different pathogens, listing symptoms, complications, and how long symptoms typically last.
Diagnostics/Treatment
- Specific diagnostic methods and treatments are outlined for various pathogens.
Prevention
- Includes methods like vaccination and reducing environmental contamination to prevent infections.
Specific Pathogen Summaries
- Each group of pathogens like E. coli (the different pathotypes), Shigella, Salmonella, Campylobacter, and others are summarized by characteristics, transmission, symptoms, pathogenesis and relevant lab information.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz tests your knowledge about Helicobacter pylori, including its virulence factors and diagnostic methods. Questions cover the role of urease, the urea breath test, and the significance of various tests for H. pylori infection. Assess your understanding of microbiological principles related to this important pathogen.
