Module 11 Flashcards
How does Shigella grow on media?
BAP- gray, moist
MAC- NLF (sonnei is LLF)
Doesn’t grow well on moderately selective media
XLD- red/colourless, grows the most
HE- green/colourless, most grow
SS- colourless, many don’t grow
GN broth- most favourable selective enrichment media for growth
What are the ID results for Shigella?
Nonmotile
Glucose pos, anaerogenic
K/A (except sonnei)
Lactose neg, ONPG neg (except sonnei)
Sucrose neg
H2S neg
Lysine neg
Deaminase neg
Urease neg
Ornithine neg (except sonnei)
Indole variable
Cit pos
How is Shigella ID confirmed?
Serological ID
Slide agglutination for O Ag
What is the clinical significance of Shigella?
Shigellosis- fecal oral contamination
Bacillary dysentery- clinical symptoms
Self limiting
Shigatoxin production
What types of Shigella are there?
A- dysenteriae
B- flexneri
C- boydii
D- sonnei
What are the two most common isolates of Shigella?
Sonnei and flexneri
How does Salmonella grow on media?
BAP- grey moist
MAC- NLF
XLD- red, maybe black centre
HE- blue green, maybe black centre
SS- colourless, maybe black centre
Bismuth- black with metallic sheen, any growth is possible Salmonella
Chrom agar- mauve
Enrichment media- good growth, NLF on sub plates
What are the ID results for Salmonella?
Glucose pos with gas
K/A, gas, H2S
Lactose neg, ONPG neg
Sucrose neg
H2S pos
Lys pos
Ornithine pos (except typhi)
PDA/TDA neg
Indole neg
Cit pos (except typhi)
Motile
Does S. typhi produce gas from glucose fermentation?
No
What is the clinical significance of S. paratyphi?
Enteric disease
Contaminated food and drink
Septicaemia
What is the treatment for S. paratyphi?
Ciprofloxacin, cotrimoxazole, chloramphenicol, ceftizoxime or azithromycin
How is Salmonella serological ID performed?
Slide agglutination
PolyOVi first, if pos test with group specific antisera
What is probably happening if PolyOVi is pos but all other antisera give neg results in Salmonella testing?
Vi Ags may be masking O Ags
What types of Salmonella infections are there?
Enteric fever- Salmonella typhi, typhoid fever, contaminated food or drink, carriers
Gastroenteritis- other Salmonella species, animal source, self limiting
When is Salmonella apparent in patient samples?
Blood- wk 1
Stool- wk 3-5
Urine- wk 3-4
O- wk 2-5
H- wk 2-6 (months)
Vi- wk 2-6 (months- carriers)
