S. enteriditis and S. typhimurium

Question 1

Epidemiology

Answer 1

~ 30,000 cases of S. gastroenteritis in US per year
Estimaes of 1.4 million cases per year with 600 deaths
Over 2,200 different serotypes have been identified

Question 2

Sources

Answer 2

poultry, pork, dog food, eggs
contamination of eggs common, can be both inside and outside of shell
fruits and veggies can carry the pathogens due to contamination
pets such as turtles and other reptiles can carry these pathogens
Playing in a sandbox is associated with disease

Question 3

Clinical syndrome

Answer 3

Symptoms begin 8-48 h after food
Sudden onset of headache, chills, ab pain, vomiting, then diarrhea with fever
lasts 1-4 days

Question 4

Pathogenesis

Answer 4

LPS release during invasion of epithelial cells of small and large intestines responsible for many symptoms
T3SS mediates invasion of epithelial cells
Extracellular cells produce toxins (including a pertussis-like toxin) that promotes inflammation and secretion

Question 5

Treatment

Answer 5

Mostly self-limiting, though complications can arise. death uncommon
Fluid and electrolyte replacement might be needed
treat pts with predisposing conditions with appropriate antibiotics
Antibiotic resistance testing can be useful as resistance is possible

Question 6

Diagnosis of Salmonella infections

Answer 6

isolation of S. in feces, or blood in the case of typhoid fever
ferment glucose, oxidase negative, and can reduce nitrate
lactose negative (MacConkey or EMB agar)
strains are motile and produce H2S
urease negative
indole negative
Serotyping with O and H antigens and PCR tests allow species ID to trace outbreaks

Question 7

General properties

Answer 7

Most common salmonella infections in US
associated with similar risk factors
diarrheal disease mostly confined to GI tract
-+ blood cultures occur but are infrequent (5%). Non-typhoidal bacteremia associated with decreased immune system: young age, old age, immune suppression
Used in two Us bioterrorismmm events