Salmonella

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Salmonella
Filename: Salmonella.ppt
4/12/2015
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Salmonella
Nomenclature
 Incidence
 Clinical syndromes
 gastroenteritis
 typhoid fever

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Salmonella


2,000 serotypes
Subgroup 1




S. cholerae-suis
S. typhi
S. enteritidis

Human Pathogens


Salmonella typhi
Salmonella paratyphi
subgroups 2-5


cold-blooded animals
environment
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S. cholerae-suis: Transmission
Humans to animals
 Animals to humans
 Humans and animals to animal feeds
Large Inoculum: 106

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Incidence in Ontario
1994
typhoid
paratyphoid
salmonellosis 1003
1992
6
85
639
1991
6
152
581
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Salmonella: Clinical Syndromes
Gastroenteritis
 Bacteremia: followed by gastroenteritis
 Enteric fever
 Asymptomatic colonization
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Salmonella: Gastroenteritis
incubation 6-48 hrs.
 nausea, vomiting, diarrhea, fever,
abdominal cramps, myalgia, headache
 2 days - 1 week: usually spontaneous
resolution
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Mechanism of Pathogenicity
Gastroenteritis
ingestion
 absorbed to brush border of epithelial cells
of small intestine and colon
 migrate to lamina propria, ileocaecal
 multiply in lymphoid follicles
 reticulendothelial hyperplasia and
hypertrophy
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Hyperplasia vs Hypertrophy
Hyperplasia : abnormal increases in the
number of normal cells (organ swells)
 Hypertrophy : increase in size of an organ

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Salmonella:Bacteremia
Usually caused by
 S. cholerae-suis
 S. typhi
 S.paratyphi
 S. dublin
Complications
 osteomyelitis (10%)
 arthritis
 endocarditis
Gram negative bacteremia is non-suppurative
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Enteric Fever: S. typhi
ileocaecal penetration
 intraluminal multiplication
 mononuclear response (macrophages)
 Salmonella remains alive
 2nd week - lymphoid hyperplasia
(mesenteric lymph nodes)
 back to bowel
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S. typhi
found in stool - enteric media and selenite
enrichment
 high antibodies
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Mechanism of
Fluid Secretion Stimulation

Arachidonic acid with the enzyme
cyclooxygenase stimulates the production
of prostaglandin which then causes an
increase in cAMP (cyclic adenosine
monophosphate) and stimulates fluid
secretion.
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Reduction of Fluid Secretion
Anti-inflammatory drugs
 aspirin - non-steroidal, anti-inflammatory

 inhibits

cyclo-oxygenase which is necessary to
produce prostaglandins
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The End
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