Infectious Entercolitis Flashcards
INFECTIOUS ENTEROCOLITIS causes a broad range of symptoms including:
- diarrhea, abdominal pain, urgency, perianal discomfort, incontinence, hemorrhage
- ____________ commonly cause pediatric infectious diarrhea leading to_______ and _______
- Enteric viruses
- Severe dehydration and metabolic acidosis
What is the morphology of Vibrio cholerae?
Comma-shaped; gram (-) baccili
What is the reservoir and mode of transmission for Vibrio cholerae?
Endemic to Ganges Valley in India and Bangledesh (India and Africa)
Reservoir = shellfish
MOT = fecal-oral; water
Is Vibrio cholerae invasive and which components of the organism are related to its virulence?
- Non-invasive and remain in lumen
- Cholera toxin
- Flagella for motility and attachment
- Hemagglutinin for detachment and shedding in stool
- Symptoms in most patients with Vibrio Cholera?
- Severe Cases?
Asypomatic or mild diarrhea
- Abrupt onset of vomiting and severe, rice water diarrhea that smells like fish after 1-5 days
What is the rate of diarrhea in severe cases of cholera and what problems can this create?
When do most deaths occur?
Treatment?
- Up to 1L/hr
- Dehydration, hypotension, electrolyte imbalance, cramping, anuria, shock, and LOC
- Death usually within first 24 hours
- Timely fluid replacement can save more than 99% of pts
________ is the most common bacterial enteric pathogen in developed countries and an important cause of travelors diarrhea (food poisoning)
Campylobacteri jejuni
What is the morphology and mode of transmission for Campylobacter spp.?
- Comma-shaped gram (-) baccili; flagellated;
- Poulty (undercooked), milk (unpasteurized), other foods
What are the 4 major properties contributing to the virulence of Campylobacter jejuni?
- Motility - flagella
- Adherence
- Toxin production - cytotoxin + cholera toxin-like enterotoxin
- Invasion
What are some of the signs and symptoms of Campylobacter infection?
- Watery diarrhea, either acute or following an influenza-like prodrome after 8 day incubation period
- Dysentery (blood stool) in minority of patients
- Fever: Enteric fever if bacteria prolif. in lamina propria and mesenteric LNs
- Sheds bacteria for 1 month after resolution
Complications of Campylobacter spp.?
- Reative arthritis (linked to HLA-B27)
- Erythema nodosum (not HLA-linked)
- Guillain-Barre syndrome (not HLA-linked)
Dx of Campylobacter infection
Which immune cell infiltrates predominate and where are they found?
- Primarily by stool culture
- Intraepithelial neutrophil infiltrates within superficial mucosa and crypts (=>cryptitis)
What is the affect of Campylobacter infection on crypt architecture?
Neutrophils in crypts (cryptitis) and submucosa and may cause crypts abcess;
HOWEVER; crypt architecture is preserved. **
What is one of the most common cause bloody diarrhea in the world?
Shigella toxin
ABX needed for Campylobacter?
No
What is the morphology of Shigella?
Mode of transmission?
Reservoir?
- Gram (-) bacilli; Unencapsulated; Non-motile; Facultative anaerobes
- Reservoir: Humans
- MOT = fecal-oral, food, water
Where are the most common sites for infection by Shigella and who is most at risk?
Most deaths occur in whom?
In US and Europe, daycares, migrant workers, travelers, and those in nursing homes; endemic in developing counties
- Most deaths occurs in children <5YO
Why is such a low dose of Shigella required to cause symptoms?
- Acid-STABLE
- Able to resist the harsh acidic enviornment of the stomach
Once Shigella are in the intestine how are they taken up and what do they do?
- Taken up by Microfold (M cells) epithelial cells
- Proliferate intracellularly, escape into LP => phagocytosed by MØ’s, in which they induce apoptosis
- Inflammatory response => damages surface epithelia and allows Shigella in lumen to access to BL membrane in L colon/ileum for invasion
Shigella most prominently infect which part of the GI, likely due to what?
What is the morphology of the mucosa?
- Left colon and Ileum –> M cells prominent in Peyers patches here
- Mucosa = ulcerated + hemorrhagic w/ pseudomembranes
What is the most common clinical presentation of a pt w/ Shigella infection?
After incubation period of 1 week, causes 1 week of diarrhea w/ fever and abdominal pain
- Unitially watery diarrhea may progress to dysenteric phase w/ sx’s lasting up to a month
What are the complications of Shigella and in whom?
- In HLA-B27+ M 20-40 YO: Sterile reactive arthritis, urtheritis, conjuntivitis
- In serotype 1 => hemolytic uremic syndrome
- Rarely, toxic megacolon and intestinal obstruction
Diagnosis and Treatment of Shigella Tocin
Dx: Stool culture
Tx:
- ABX
- DONT give anti-diarrheals => delay clearance
Salmonellosis is usually due to which type of Salmonella?
Salmonella enteritidis (non-typhoid salmonella)
Salmonella eneteritidis is a ___________ bacteria that is most commonly transmitted how?
Which age groups most affected?
Which time of year do infections peak?
- Gram (-) baccilus
- Meat, poultry, and eggs/milk
- Young children and older adults
- Peak incidence in fall and summer
Who is more likely to get of Salmonella infection?
- Atrophic gastritis or on acid-suppressive therapy (PPIs)
- Genetic defects in TH17 –> Disseminated salmonellosis
Which virulence factor allows for Salmonella invade and infect humans?
Explain the pathogenesis of invasion.
- Type III secretion system transfers bacterial proteins –> M cells and enterocytes
- Proteins (+) Rho GTPases –> rearrange actin and bacterial endocytosis, allowing growth
What do the flagellin and LPS of Salmonella enteritidis activate inside humans are what does this result in?
- Flagellin –> TLR5 –> Increased inflammtory response
- LPS –> TLR4
How do Salmonella enteritdis indirectly cause increased neutrophils and potentiate mucosal damage?
Secrete molecule inducing epithelial cells to release eicosanoid hepoxilin A3
Which immune cells limit infection by Salmonella enteridis ?
TH1 and TH17
What is essential for the diagnosis of Salmonella infection?
+ stool culture
- Salmonella enteritidis (salmonellosis) profuse watery diarrhea => dystentary that lasts _______ and treated how?
- 1 week
- Self limited; do not give ABX
Typhoid fever (enteric fever) is caused by which organism and its 2 subtypes?
Which subtype is associated with endemic countries and which with travelers?
- Salmonella enterica
- Subtypes:
- Typhi (endemic countries)
- Paratyphi (travelers)
What is the reservoir for Salmonella enterica?
Mode of transmission?
- Humans = reservoir
- MOT = fecal-oral and water
Typhoid fever (Salmonella enterica) is strongly associated with travel to which countries?
India, Mexico, Philippines, Pakistan, El Salvador, and Haiti
S. typhi or S. paratyphi can colonize the _________, causing __________ and ________.
Gallbladder
Gall stones and chronic carrier state.
Explain the pathogeneis of S. typhi infection (i.e., how do they invade?)
- Survive in gastric acid –> small intestine, where they are taken up by M cells =>
- Engulfed by mononuclear cells in lymph tissue
- Disseminate throughout the body via lymph and blood causing phagocyte and lymph tissue reactive hyperplasia
Morphology of S. typhi infection (typhoid fever)?
- Enlarged/plateu-like Peyer’s patches in terminal ileum and draining mesenteric LN
- Acute and chronic inflammatory cells in lamina propria => necrotic debris and mucosal ulcers that may perforate.
- Liver forms tyhoid nodules (focal hepatocyte necrosis with MO aggregates)
- Spleen: elarged with red pulp and obliterated follcular markings
What is the clinical course of Typhoid fever?
- Dysentary, N/V, adominal pain => asympomatic phase => that leads to bacteremia in 90% of patients: fever, flu-like sx and abdominal pain that occurs without ABX.
Are ABX recommended for Typhoid Fever?
YES; can prevent progressiopn
In patients with Typhoid Fever, not treated w/ antibiotics what additional signs and symptoms may develop?
- Sustained high fevers
- Tender abdomen which may mimic appendicits
- Rose spots = erythematous maculopapular lesions on chest and abd.
Systemic dissemination of S. typhi may lead to what complications?
- Encephalopathy/ Meningitis/ Seizures (Neuro)
- Endocarditis/ myocarditis (Cardio)
- Pneumonia (Pulm)
- - Cholecystitis
Patients with _____________, who get S. typhi are more likely to get osteomyelitis.
Sickle cell disease
