Nomenclature

Incidence

Clinical syndromes

gastroenteritis

typhoid fever

2,000 serotypes

Subgroup 1
- S. cholerae-suis
- S. typhi
- S. enteritidis

subgroups 2-5
- cold-blooded animals
- environment

Human Pathogens
- Salmonella typhi
- Salmonella paratyphi

S. cholerae-suis: Transmission

Humans to animals

Animals to humans

Humans and animals to animal feeds

Large Inoculum: 106

Incidence in Ontario

1994 1992 1991

typhoid 6 6

paratyphoid 85 152

salmonellosis 1003 639 581

Salmonella: Clinical Syndromes

Gastroenteritis

Bacteremia: followed by gastroenteritis

Enteric fever

Asymptomatic colonization

Salmonella: Gastroenteritis

incubation 6-48 hrs.

nausea, vomiting, diarrhea, fever, abdominal cramps, myalgia, headache

2 days - 1 week: usually spontaneous resolution

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

Hyperplasia vs Hypertrophy

Hyperplasia : abnormal increases in the number of normal cells (organ swells)

Hypertrophy : increase in size of an organ

Salmonella:Bacteremia

S. cholerae-suis

S. typhi

S.paratyphi

S. dublin

osteomyelitis (10%)

arthritis

endocarditis

Enteric Fever: S. typhi

ileocaecal penetration

intraluminal multiplication

mononuclear response (macrophages)

Salmonella remains alive

2nd week - lymphoid hyperplasia (mesenteric lymph nodes)

back to bowel

found in stool - enteric media and selenite enrichment

high antibodies

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.

Reduction of Fluid Secretion

Anti-inflammatory drugs

aspirin - non-steroidal, anti-inflammatory
- inhibits cyclo-oxygenase which is necessary to
- produce prostaglandins