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Weber AC, Levison AL, Srivastava SK, Lowder CY. J Ophthalmic Inflamm Infect. 2015 Dec;5(1):28. Epub 2015 Oct 5. [Open Access.] PMID: 26437938; PMCID: PMC4593987.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

Shown is a patient with endogenous endophthalmitis caused by Listeria monocytogenes, a foodborne bacterium. In the above view of both eyes, it is seen that shedding of iris pigment in the infected right eye has resulted in heterochromia.[1]

Foodborne disease (FBD) is an important cause of morbidity and mortality in the United States. The Centers for Disease Control and Prevention (CDC) estimates that each year, approximately 1 in 6 Americans (or 48 million people) get sick as a result of FBD, with 128,000 hospitalized and 3000 dying.[2] FBD can result from several causes, including preformed toxins, invasive or toxin-producing bacteria, viruses, parasites, and heavy metals. According to the National Outbreak Reporting System, in 2020 FBD was responsible for 299 outbreaks, which caused 5987 illnesses, 641 hospitalizations, and 14 deaths.[3]

Image courtesy of Amanda Oakley, MBChB, FRACP.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

A 35-year-old man presents with nausea, abdominal cramping, and headache that started while he was eating mahi-mahi, sautéed spinach, and French fries at a restaurant. He denies experiencing any vomiting or diarrhea. On examination, he has a rash on his face and upper trunk (shown).

Which of the following statements about this patient's condition is most accurate?

  1. Antibiotics are of use in shortening the course of disease
  2. Prolonged neurologic sequelae are common with this condition
  3. Proper cooking of the fish would have prevented his illness
  4. Proper washing of the spinach would have prevented his illness
  5. The short incubation period is consistent with ingestion of a preformed toxin
Image courtesy of Amanda Oakley, MBChB, FRACP.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

Answer: E. The short incubation period is consistent with ingestion of a preformed toxin.

The short incubation period (10-30 minutes) and the clinical presentation are consistent with scombroid poisoning (often referred to as histamine fish poisoning because many cases are caused by nonscombroid fish). Histamine fish poisoning results in nausea, abdominal cramping, diarrhea, and a distinctive flushing of the face and upper torso (shown).[4] Other symptoms include palpitations and headache.

Histamine fish poisoning results from the consumption of fish that was inadequately refrigerated, resulting in bacterial production of biogenic amines and decarboxylation of histidine to histamine. The amines and histamines are stable to heat, and cooking does not prevent illness.

Image from Wikimedia Commons | Valdavia.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

A 30-year-old woman complains of nausea, vomiting, and diarrhea, that started 6 hours after she ate pan-fried mackerel. She has also noted burning with urination. She was managing the condition at home until she drank a chilled glass of wine the following day and noticed that her symptoms worsened; she also found that holding the cold glass caused tingling pain in her hands. The progressing symptoms prompted her to seek medical attention.

Which of the following toxins is responsible for this patient's symptoms?

  1. Batrachotoxin
  2. Brevetoxin
  3. Ciguatoxin
  4. Microcystin
  5. Tetrodotoxin
Table courtesy of Medscape.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

Answer: C. Ciguatoxin.

Ciguatera poisoning is an FBD associated with seafood consumption. It is caused by ingestion of ciguatoxins produced by dinoflagellates that are present in tropical and subtropical waters.[5] Ciguatoxins undergo biomagnification and may occur in high concentrations in carnivorous tropical and subtropical fish (eg, mackerel, grouper, and amberjack).

Ciguatera poisoning features gastrointestinal (GI) and neurologic symptoms. Cold allodynia (a burning sensation on exposure to cold; sometimes referred to as "hot-cold reversal") and worsening of symptoms with alcohol consumption are highly suggestive of ciguatera poisoning. In 2020, 13 outbreaks of ciguatera poisoning resulted in 42 illnesses and six hospitalizations in the United States.[3]

Image courtesy of Medscape.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

A 19-year-old male presents with diarrhea, fatigue, and a 5-lb weight loss, all of which were present or developed over the preceding 2 months. He has no history of recent international travel, recent antibiotic use, nausea, vomiting, or abdominal pain. Stool studies are performed. A stool wet mount with iodine stain is pictured.

Which of the following statements about this man's condition is most accurate?

  1. Bloody diarrhea is common, owing to the invasive nature of the causative organism
  2. Ciprofloxacin is first-line therapy for this condition
  3. Transmission occurs via fecal-oral contamination
  4. Human immunodeficiency virus (HIV) testing should be performed to evaluate for immunocompromise
  5. Mosquitoes serve as a vector for the causative organism
Image courtesy of Medscape.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

Answer: C. Transmission occurs via fecal-oral contamination.

Giardiasis is a common cause of diarrheal disease in the United States and throughout the world.[6] Infection typically occurs from fecal-oral contamination, which can be attributable to poor hygiene, sexual transmission, or consumption of contaminated water (eg, while hiking). Diagnosis may be made by means of enzyme-linked immunoassay of the stool or examination of the stool for ova and parasites, which may reveal Giardia lamblia cysts or trophozoites (shown).

Yamamoto K, Yanagawa Y, Oka S, Watanabe K. PLoS Negl Trop Dis. 2020 Mar 19;14(3):e0008013. [Open Access.] PMID: 32191702; PMCID: PMC7081979.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

A patient presents with abdominal pain and diarrhea, which he has had for 3 months, and is referred for a colonoscopy, which reveals the pictured lesions. His symptoms followed a vacation in Mexico. Which of the following organisms is most likely responsible for the man's condition?

  1. Campylobacter jejuni
  2. Entamoeba histolytica
  3. Escherichia coli
  4. Giardia intestinalis
  5. Vibrio cholerae
Yamamoto K, Yanagawa Y, Oka S, Watanabe K. PLoS Negl Trop Dis. 2020 Mar 19;14(3):e0008013. [Open Access.] PMID: 32191702; PMCID: PMC7081979.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

Answer: B. Entamoeba histolytica.

Amebic colitis, the patient's condition, is uncommonly encountered in the United States. Common symptoms include cramping, abdominal pain, and watery diarrhea. Risk factors include travel to endemic areas (Africa, India, Mexico, and Central and South America), being an immigrant or refugee from endemic areas, being a man who has sex with men, and being exposed to institutions with poor sanitary conditions.[7]

The colonoscopic image on the previous slide shows white-coated ulcerative lesions present in the cecum. The image on this slide, from another individual with amebic colitis, reveals similar lesions, which were found from the cecum to the sigmoid colon.[8]

A 35-year-old male migrant worker presents to the emergency department (ED) by ambulance for a generalized tonic-clonic seizure. In the ED, the seizure continues despite administration of benzodiazepines. The patient is intubated and placed on a propofol infusion for status epilepticus.

Ingestion of the eggs of which of the following organisms could be responsible for this patient's presentation?

  1. Ascaris lumbricoides
  2. Entamoeba histolytica
  3. Enterobius vermicularis
  4. Strongyloides stercoralis
  5. Taenia solium
Image courtesy of Medscape.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

Answer: E. Taenia solium.

T solium causes the parasitic tissue infection cysticercosis.[9] The slide shows nonenhanced (left) and enhanced (right) computed tomography (CT) scans of the head in a patient with a form of the disease, neurocysticercosis, that may result in seizures, strokes, or hydrocephalus. Cysticercosis is uncommon in the United States (approximately 1000 cases/year), but its incidence is rising owing to increased immigration from and travel to endemic areas.

A 22-year-old male college student presents to the ED with severe nausea and vomiting. He states that during the week he mostly eats leftover food from restaurants he goes to on the weekend. He reports that he began to experience symptoms several hours after eating old fried rice.

Which of the following organisms is most likely to be responsible for this patient's symptoms?

  1. Bacillus cereus
  2. Clostridium perfringens
  3. Clostridium botulinum
  4. Escherichia coli
Image from the CDC.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

Answer: A. Bacillus cereus.

The image shown demonstrates B cereus colonies growing on a sheep's-blood agar plate.

B cereus is a gram-positive aerobic bacterium that can cause FBD; it is most commonly associated with improperly cooked fried rice. B cereus produces endospores that can survive temperatures as high as 100°C. In foods that are improperly refrigerated, the endospores readily germinate.[10]

Two specific forms of B cereus disease exist: diarrheal and emetic. In the diarrheal form, patients develop diarrhea and abdominal pain after an incubation period of roughly 12 hours. In the emetic form, which is usually associated with improperly cooked rice, enterotoxins induce nausea and vomiting within a couple of hours.

Image from Wikimedia Commons | Baldwin040.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

A large number of passengers and crew members on a cruise to Jamaica begin suffering from stomach pain, nausea, diarrhea, and vomiting. Considering the most common source of food poisoning on cruise ships, which of the following agents is most likely involved?

  1. Enterotoxigenic E coli
  2. Norovirus
  3. Salmonella enteritidis
  4. Staphylococcal enterotoxin B
  5. Vibrio cholerae
Image from the CDC.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

Answer: B. Norovirus.

Norovirus (shown), an RNA virus, is responsible for roughly 50% of cases of FBD in the United States.[11]  Norovirus is highly transmissible via fecally contaminated food or water and is commonly associated with FBD on cruises. Between 2010 and 2019, Norovirus was implicated in 95 (80%) of the 119 outbreaks of FBD on international cruise ships.[12] For example, the ship "Oasis of the Seas," seen in the previous slide, was the site of a 2019 Norovirus outbreak that sickened hundreds of passengers and a number of crew members.[13]

Norovirus causes damage to the microvilli in the small intestine, leading to profuse vomiting, watery diarrhea, low-grade fever, and malaise. Treatment is generally supportive, and the disease is usually self-limited.

Image courtesy of Medscape.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

A 30-year-old man presents with several days of abdominal cramping, nausea, vomiting, bloody diarrhea, and lethargy. Urinalysis shows proteinuria and hematuria. A complete blood count demonstrates anemia and thrombocytopenia. A peripheral blood smear is shown.

Which of the following statements about this condition is most accurate?

  1. The case-fatality rate for treated patients is higher than 50%
  2. This condition occurs most frequently in persons aged 20-40 years
  3. This condition is caused by ingestion of preformed toxins
  4. This condition is the most common cause of acute renal failure in children
  5. Reactive thrombocytosis is commonly encountered
Image courtesy of Medscape.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

Answer: D. This condition is the most common cause of acute renal failure in children.

The peripheral blood smear pictured shows schistocytes (arrows) caused by intravascular hemolysis and thrombocytopenia resulting from thrombocyte consumption, sequestration, and destruction.

Colitis caused by Shiga toxin–producing E coli (STEC), such as E coli O157:H7, carries a risk for subsequent hemolytic-uremic syndrome (HUS). HUS may occur at any age but is most common in children aged 7 months to 6 years; it is the most frequent cause of acute renal failure in this age group.

Image from the CDC.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

A 4-month-old girl is brought to the ED by her parents for decreased activity and poor feeding. The parents note that the infant (shown) has not had a bowel movement in the past 24 hours. They deny feeding the infant honey, corn syrup, or home-canned foods but report having given her chamomile tea for colic 2 weeks previously.

Which of the following statements about this infant's condition is most accurate?

  1. Antibiotic therapy should be initiated
  2. Ascending paralysis has occurred as a consequence of demyelinating disease
  3. Her condition is caused by ingestion of preformed toxin
  4. Nearby construction is a risk factor for disease
  5. Therapy is limited to supportive care
Image from CDC.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

Answer: D. Nearby construction is a risk factor for disease.

The above photomicrograph demonstrates Clostridium botulinum stained with gentian violet.

The incubation period of illness in this girl (2-4 weeks) is consistent with infant botulism and not with foodborne botulism (incubation period, 18-36 hours), which is associated with improperly preserved foods.

Whereas children and adults must ingest preformed toxin to develop clinical botulism, infant botulism may occur after ingestion of C botulinum spores in unspoiled food (honey or corn syrup); botulinum toxin is produced in the infant's gut. A potential source of infant botulism is chamomile tea.[14,15] Nearby construction is another risk factor, owing to soil disturbance.

Image from US Department of Agriculture | Scott Bauer.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

Over a 4-week period, a total of 15 persons are admitted to intensive care units (ICUs) in four states for signs and symptoms of sepsis and meningitis. With the use of a standard CDC questionnaire, it is determined that the affected persons had all ingested a specific brand of cantaloupe within the preceding 4 weeks.

Which of the following pathogens is most likely responsible for this epidemic?

  1. E coli O157:H7
  2. Hepatitis A virus
  3. Listeria monocytogenes
  4. Salmonella typhimurium
  5. Vibrio vulnificus
Adapted map and inset image of L monocytogenes from the CDC.

10 Cases of Food Poisoning: Find the Pathogen Responsible

David Vearrier, MD, MPH | April 22, 2022 | Contributor Information

Answer: C. Listeria monocytogenes.

L monocytogenes is the organism responsible for invasive listeriosis. Infection primarily occurs through consumption of contaminated food. Listeriosis outbreaks are common, with one or more outbreaks occurring in each of the past 11 years.[16]

Listeria causes a broad spectrum of illness, and host factors are an important determinant of disease severity.[17] Immunocompetent children and adults may have mild symptoms or a febrile gastroenteritis. Newborns, pregnant women, older adults, and immunocompromised patients are more likely to develop invasive listeriosis, which may result in sepsis, meningitis, and death.

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