Infectious Diarrhea Cheat Sheet and Quiz

Infectious Diarrhea Cheat Sheet and Quiz

Infectious diarrhea by precipitating event and most likely pathogen
Traveler's diarrhea e-coli
Diarrhea after a picnics and egg salad Staphylococcus Aureus
Diarrhea from shellfish Vibrio cholerae
Diarrhea from poultry or pork Salmonella
Diarrhea following raw egg ingestion Salmonella
Diarrhea in a patient post antibiotics C. Difficile
Diarrhea in poorly canned home foods C. perfringens
Diarrhea breakout in daycare center Rotavirus
Diarrhea on a Carnival Cruise Ship Norovirus
Diarrhea after drinking (not so) fresh mountain stream water Giardia
Question 1
Which of the following pathogens is more frequently associated with the consumption of poultry?
Escherichia coli
Question 1 Explanation: 
In a 2013 report, Centers for Disease Control and Prevention (CDC) investigators used data spanning the decade between 1998 and 2008 to report estimates for annual US food-borne illnesses, hospitalizations, and deaths attributable to each of 17 food categories. The following were among their findings:
  • Leafy green vegetables were the most common cause of food poisoning (22%), primarily due to Norovirus species, followed by E coli O157.
  • Poultry was the most common cause of death from food poisoning (19%), with Listeria and Salmonella species being the main infectious organisms.
  • Dairy items were the second most frequent causes of foodborne illnesses (14%) and deaths (10%), with the main factors being contamination by Norovirus from food handlers and improper pasteurization resulting in contamination with Campylobacter species.
Question 2
When vomiting is the major presenting symptom, which of the following pathogens is more likely responsible?
Staphylococcus aureus
Question 2 Explanation: 
The following are some of the salient features of food poisoning:
  • Acute diarrhea in food poisoning usually lasts less than 2 weeks. Diarrhea lasting 2-4 weeks is classified as persistent. Chronic diarrhea is defined by duration of more than 4 weeks.
  • The presence of fever suggests an invasive disease. However, sometimes fever and diarrhea may result from infection outside of the gastrointestinal tract, as in malaria.
  • A stool with blood or mucus indicates invasion of the intestinal or colonic mucosa.
  • When vomiting is the major presenting symptom, suspectS aureus, Bacillus cereus, or Norovirus.
Question 3
Which of the following statements is false regarding food poisoning?
Most cases result from improper food handling
Bacteria are responsible for approximately 75% of the outbreaks of food poisoning
Inadequate reheating is a common cause of food poisoning
Most cases result from food prepared at home
Question 3 Explanation: 
The CDC estimates that 97% of all cases of food poisoning result from improper food handling; 79% of cases result from food prepared in commercial or institutional establishments, and 21% of cases result from food prepared at home
Question 4
Bacterial culture is mandatory in which of the following scenarios?
The patient shows signs of dehydration
The patient has a notable inflammatory response at presentation
The patient has suspected antibiotic-associated diarrhea
The patient has fever or symptoms lasting longer than 3-4 days
Question 4 Explanation: 
Obtain the following laboratory studies in cases of suspected food poisoning:
  • Perform Gram staining and Loeffler methylene blue staining of the stool for white blood cells (WBCs) to help differentiate invasive disease from noninvasive disease.
  • Perform microscopic examination of the stool for ova and parasites.
  • Bacterial culture for enteric pathogens, such asSalmonella, Shigella, and Campylobacter organisms, becomes mandatory if a stool sample shows positive results for WBCs or blood or if patients have fever or symptoms persisting for longer than 3-4 days.
  • Perform blood culture if the patient is notably febrile.
  • Perform complete blood count with differential, serum electrolyte assessment, and blood urea nitrogen and creatinine levels to help assess the inflammatory response and the degree of dehydration.
  • Assay for Clostridium difficile to help rule out antibiotic-associated diarrhea in patients receiving antibiotics or in those with a history of recent antibiotic use.
Question 5
Antiperistaltics (opiate derivatives) are contraindicated in which of the following groups?
Patients who are dehydrated
Patients with bloody diarrhea
Patients with vomiting
Patients with comorbid otitis media
Question 5 Explanation: 
Absorbents (eg, Kaopectate, aluminum hydroxide) help patients have more control over the timing of defecation. However, they do not alter the course of the disease or reduce fluid loss. Note the following:
  • An interval of at least 1-2 hours should elapse when using other medications with absorbents.
  • Antisecretory agents, such as bismuth subsalicylate, may be useful. The dose is 30 mL every 30 minutes, not to exceed 8-10 doses.
  • Antiperistaltics (opiate derivatives) should not be used in patients with fever, systemic toxicity, or bloody diarrhea or in patients whose condition either shows no improvement or deteriorates.
  • Diphenoxylate with atropine is available in tablets (2.5 mg of diphenoxylate) and liquid (2.5 mg of diphenoxylate/5 mL). The initial dose for adults is 2 tablets 4 times a day (ie, 20 mg/d). The dose is tapered as diarrhea improves.
  • Loperamide is available over the counter as 2-mg capsules and as a liquid (1 mg/5 mL). It increases the intestinal absorption of electrolytes and water and decreases intestinal motility and secretion. The dose in adults is 4 mg initially, followed by 2 mg after each diarrhea stool, not to exceed 16 mg in a 24-hour period.
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