Salmonella
Terms
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- Gram stain, shape
- Negative, rod
- Aerobic or anaerobic or???
- Facultative aerobic
- 3 groups??
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1) Humans only
2) Adapted for a particular species
3) Paratyphoids - no particular host preference... Infects both humans and animals - 2 species are??
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S. bongori
S. enterica - S. bongori infects?
- Cold blooded animals
- S. enterica infects?
- Mostly warm blooded
- Naming of salmonella (3 things)
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1) Disease syndrome or animal first isolated from
2) Place first reported
3) Antigenic formula - Antigenic structure (Kauffmann-White scheme)
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O-somatic capsule
Vi-Capsular antigen
H (phases 1 and 2) Flagellar antigen -heat labile - Phase variation (antigenic) is?
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H antigen exists in 2 phases. An indiv bacterial cell can have flagella in either phase 1 or 2. Bact originally in one phase can switch during multiplication.
Non-motile strains don't demonstrate phase variation
Need to ID both phases. - H-O variation
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Loss of H antigen or flagella
Usually 1 direction only
Motile -> Non motile
Spontanous change is rare and often irreversible
Genetic material for enzyme that synthesizes flagella is lost/altered. - S-R variation
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Smooth to rough form
Known to occur in practically all bacteria
Gradual change
Rough organisms give non specific agglutination.
Low virulence - can be vax strain.
No change in flagellar antigen - O variation
- change in lipopolysaccharides on surface
- V-W variation
- loses/changes outernost polysaccharide layerantigen
- Salmonella ID - selective media, test
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MacConkey, Brilliant Green, XLD
API, TSI, Indole, urea - MacConkey
- Tan (non lactose fermentor)
- Brilliant Green
- red (like Citrobacter, E.coli is grn)
- XLD
- Purple (Citrobacter/E. coli grn)
- Pathogenesis
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Ingestion
Colonization of lower intestine (ilieum and cecum)
Mucosal invasion (cytotoxin)
Acute inflammation (ulceration, prostoglandin, enterotoxins, cytokines)
Activation of adenyl cyclase (increase cAMP)
Fluid production (lg and sm bowel)
Diarrhea - Virulence
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Antigenic phaes variation
sequestration of nutritional factors
Resistance to serum killing
Antimicrobial resistance
Pathogenicity islands - Leading cause of ??
- Human foodborne illness worldwide (1-5 million cases in US yearly
- Human salmonella serotypes
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S paratyphi A
S paratyphi B
S paratyphi C
S typhi
Also, non-host adapted Salmonella strains