Shigella spp Isolation
and Serotyping
Shigella spp
• Shigella is a group of bacteria
that has four different species
that cause gastrointestinal
illness.
•Group A - Shigella dysenteriae
Group B - Shigella flexneri
Group C - Shigella boydii
Group D - Shigella sonnei
Shigella spp Isolation
• Shigella organisms may be very difficult to distinguish
biochemically from Escherichia coli.
• Shigella species are Gram-negative, facultatively anaerobic,
nonsporulating, nonmotile rods in the family Enterobacteriaceae.
• They do not decarboxylate lysine or ferment lactose within 2 days.
NON-LACTOSE
FERMENTERS:
COLOURLESS
COLONIES
MacConkey Agar
LACTOSE FERMENTERS: RED/PINK COLONIES
Identification bacterial pathogens in stool by
biochemical testing
Non-lactose fermenting, morphologically different, and well-isolated Colony from
SS and/ or Mac.
1. Inoculate the Kliger’s Iron Agar (KIA) agar tube by touching the top of a
colony using sterilized inculcation needle and stabbing to the bottom of the
KIA. After stabbing, immediately streak the slanted surface of the agar.
2. Inoculate the Motility-Indole-Ornithine (MIO) tube by stabbing, in a single upand-down needle.
3. Inoculate the Lysine-Iron agar (LIA) by stabbing the butt to the bottom once
and streaking the slant.
4. Inoculate the urea broth tube by placing the needle in the tube and shaking the
needle.
5. Incubate all tubes overnight at 35-37 Co
Conventional biochemical screening sets
Serogroups and Serotypes
 Each serologic group contains specific or
major Somatic Antigen (O Ag) Characteristic
of this group
 Each serologic group is subdivided on the
basis of antigenic structure into Serotypes
 Serotypes is further subdivided into
subserotypes on the basis of antigenic
structure
Serogroup
Serotypes
Subserotypes
Serogroups and Serotypes are
determined by visual inspection of slide
agglutination assays, with commercial
antisera used as described by the
manufacture.