Two important serotypes: typhimurium, and typhi.
Typhi is exclusively human.
Other salmonella can be associated with food (egg and poultry) or pet turtle.
All strains are called Salmonella enterica. The species is divided based on serotype.
Serotypes are based on the cell wall (O), flagellar (H), and capsular (Vi, analogous to K) antigens.
Development of disease depends on
Ingestion of salmonellae in small intestine
-> Enter epithelial cells by endocytosis (induced by bacterial protein)
-> Phagocytosis by macrophages in the sub-mucosa
-> Multiply intracellularly
-> Spread to reticuloendothelial system by macrophages
-> Cause lymphoid hyperplasia and hypertrophy
-> Re-enter bowel via liver and gall bladder
-> Inflammation and increase cAMP
-> Active fluid secretion and diarrhoea
Caused by serotype enteriditis and typhimurium
Develops within 48 hours of ingestion
Generally self-limiting (48 to 72 hours)
Caused by serotype typhi (uncommonly by other types)
Severe, life-threatening systemic illness
Incubation 5 to 21 days.
Mortality 15% if untreated. <1% if treated with antibiotics.
Last for 3-4 weeks.
Most strains are Lac-.
Produce gas and acid during fermentation of glucose.
Produce H2S from sulfur containing amino acid.
Multiple flagella over the cell surface
Facultative, intracellular.
Survives in phagocytic cells.
Can be isolated on MacConkey agar.
First line: ceftriaxone
Second line: fluoroquinolone (e.g. ciprofloxacin)
Food and personal hygeine.
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Created | 20040331 |