Clinical Features: Infectious Disease of the Small Intestine + Colon

Question 1

Vibrio cholera

Answer 1

~Most patients are asymptomatic or have mild diarrhea as the bacterium remains within intestinal lumen
~Severe cases: ‘rice water diarrhea’ with fishy odor
~1-5 day incubation period
~Dehydration, hypotension, muscle cramping, anuria, shock, loss of consciousness, and death (within 24 hours)

Question 2

Campylobacter jejuni

Answer 2

~Most common bacterial enteric pathogen in developed countries
~Acute watery diarrhea or may follow influenza-like prodrome
~Dysentery can occur but only in some strains

Sequelae from campylobacter infection:
~HLA-B27 = reactive arthritis
~Erythema nodosum
~Guillain-Barre syndrome: ascending flaccid paralysis due to immune-mediated inflammation of peripheral nerves due to molecular mimicry due to LPS cross-reactivity

Question 3

Shigella

Answer 3

~Most common cause of bloody diarrhea
~Fecal-oral transmission or via contaminated food/H2O
~Daycare nursing home, migrant workers, travel to developing country

~Self-limited diarrhea, fever, abdominal pain
~The initial watery diarrhea phase progresses to dysentery in approximately 50% of people that can last up to a month

~Subacute patients have waxing and waning diarrhea
~Children: shorter duration, more severe

Complications:
~Triad: Sterile reactive arthritis, urethritis, conjunctivitis in HLA-B27 (+) males 20-40 years old
~Serotype 1 leads to toxin causing hemolytic uremic syndrome

Question 4

Salmonella

Answer 4

~Incidence peaks in summer and fall
~Commonly in young children and older adults
~Food poisoning due to ingestion of contaminated food (raw/undercooked meat, poultry, eggs, milk)
~Large outbreaks in centralized food processing

~Range from loose stool to profuse diarrhea to dysentery

~Severe illness more likely in patients with malignancy, immunosuppression, alcoholism, CV dysfunction, sickle cell disease, and hemolytic anemia

Question 5

Yersinia

Answer 5

~Abdominal pain +/- fever, diarrhea, nausea, vomiting
~Teens/young adults: mimics appendicitis
~Younger children: enteritis and colitis predominate
~Extra-intestinal: Pharyngitis, arthralgia, erythema nodosum

~iron enhances virulence and stimulates systemic dissemination

~Individuals with increased non-heme iron (chronic forms of anemia or hemochromatosis) are at increased risk to develop sepsis and die

~Post-infectious complications: Reactive arthritis, urethritis, conjunctivitis, myocarditis, erythema nodosum, and kidney disease

Question 6

Enterotoxigenic Escherichia coli

Answer 6

~Principal cause of traveler’s diarrhea w/ the other cause
–> campylobacter

~Secretory, non-inflammatory diarrhea, dehydration and if severe, shock

~Spread via contaminated food or water
~Children < 2 years are particularly susceptible

Question 7

Enteropathic Escherichia coli

Answer 7

~Watery diarrhea

~Pretty vague

Question 8

Enterohemorrhagic Escherichia coli

Answer 8

~O157:H7 & non-O157:H7
~Consumption of undercooked beef (cows are reservoir), milk and vegetables
~Both serotypes produce shiga-like toxins and clinically resemble shigella dysenteriae
~O157:H7 is more likely to produce outbreaks, bloody diarrhea, hemolytic uremia syndrome (HUS), and ischemic colitis
~Antibiotics are CONTRAindicated because killing bacteria increases the amount of toxin released and enhances HUS

Question 9

Enteroinvasive Escherichia coli

Answer 9

~Invade epithelial cells causing nonspecific, acute self-limited colitis
~Transmitted via food, water or human-human contact
~Most commonly infect young children in developing countries

Question 10

Clostridium difficile

Answer 10

~Fever, leukocytosis, abdominal pain, cramps, watery diarrhea, dehydration.

~Most colonized patients are asymptomatic

~Protein loss leads to hypoalbuminemia –> peripheral edema

~Fecal leukocytes and occult blood may be present, but grossly bloody diarrhea is uncommon

Question 11

Tropheryma whippelii

Answer 11

~Whipple disease – multivisceral chronic disease –> malabsorptive diarrhea, weight loss, arthralgia

~Rare, systemic condition due to actinomycete Tropheryma whippelii

~Malabsorptive diarrhea caused by impaired lymphatic transport

~Caucasian males (farmers, occupational exposure)

Question 12

Norovirus

Answer 12

~Causes ∼ 1/2 of all gastroenteritis outbreaks worldwide

~Common cause of sporadic gastroenteritis in developed countries

~Most common cause of acute gastroenteritis requiring medical attention

~2nd most common cause of severe diarrhea in infants and young children

~This is what breaks out on cruise ships

~NAUSEA, VOMITING, ABD PAIN

~SERIOUS PROBLEM IN IMMUNOCOMPROMISED

Question 13

Rotavirus

Answer 13

~Most common cause of severe childhood diarrhea and diarrheal mortality worldwide

~Children 6-24 months are most susceptible – daycare population

~0 - 6 months: passive immunity from maternal breast milk

~2 years and on: immunity that develops following the first or second infection

~Rotavirus vaccine is associated with intussusception

~Net secretion of H2O/electrolytes, malabsorption, osmotic diarrhea

Question 14

Adenovirus

Answer 14

~Nonspecific signs and symptoms after 1 week incubation period:

~Diarrhea, vomiting, abdominal pain
+/ fever and weight loss

Question 15

Ascaris lumbricoides

Answer 15

~Can cause obstruction of the biliary tree
~Hepatic abcesses
~Ascaris PNA

Question 16

Strongyloides

Answer 16

~Strong tissue reaction and induce peripheral ~Eosinophilia

~Immunocompromised individuals can have an overwhelming autoinfection

Question 17

Enterobius vermicularis

Answer 17

~Rarely a severe illness

~Cause rectal itching

Question 18

Intestinal Cestodes

Answer 18

~Symptoms: diarrhea, abdominal pain, nausea

Three primary species:

Diphyllobothrium latum (fish tapeworm) = causes B12 deficiency and megaloblastic anemia because it competes with the host for dietary B12

• taenia solium (pork tapeworm)
• hymenolepis nana (dwarf tapeworm)

Question 19

Entamoeba histolytica

Answer 19

x• fecal-oral transmission
• causes liver abscesses and dysentery
• abdominal pain, bloody diarrhea, or weight loss
• acute necrotizing colitis and megacolon – both associated with significant mortality

Question 20

Giardia lamblia

Answer 20

x• MOST COMMON parasitic pathogen in human and spread fecally contaminated water or food
• Secretes products that damage brush border = malabsorption

Question 21

Cryptosporidium

Answer 21

x• Chronic diarrhea in AIDs patients

• Malabsorption of sodium, chloride secretion, an increased tight junction permeability – non-bloody watery diarrhea

Question 22

Typhoid

Answer 22

• Anorexia, abdominal pain, bloating, nausea, vomiting, bloody diarrhea
• Followed by asymptomatic phase that leads to bacteremia and fever with flu-like symptoms
• 90% of pts have (+) blood cultures during febrile phase
• antibiotics can prevent further disease progression
• Gallbladder colonization can be associated with gallstones and the chronic carrier state
• Rose spots: small erythematous maculopapular lesions on chest & abdomen

• Extra-intestinal: osteomyelitis (especially sickle cell patients), encephalopathy, meningitis, seizures, endocarditis, myocarditis, pneumonia, cholecystitis

Question 23

Enteroaggregative Escherichia coli

Answer 23

• can also cause traveler’s diarrhea
• Non-bloody diarrhea that is prolonged in AIDS patients
can cause diarrhea in children and adults from developing countries - also non febrile
not too much known about it

Question 24

Necator duodenale and Ancylostoma duodenale =

Answer 24

• suck blood and reproduce in the duodenum –> multiple superficial erosions, focal hemorrhage, and inflammatory infiltrates
• Chronic infection leads to iron deficiency anemia