SHIGELLA BROTH ISO 21567
CAT Nº: 2078
Selective enrichment medium of Shigella spp according to ISO
21567:2004 Standard
FORMULA IN g/l
Casein Peptone
20.00 Sodium chloride
5.00
Dextrose
1.00
Polisorbate 80
1.30
Potassium hydrogen
phosphate
2.00
Novobiocin
Potassium dihydrogen
phosphate
2.00
0.0055
Final pH 7.0 ± 0.2 at 25ºC
PREPARATION
Suspend 31,5 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent
agitation. Boil for one minute until complete dissolution. AVOID OVERHEATING. DO NOT AUTOCLAVE. Dispense into
appropriate containers and use in the same day. Do not storage. The color is amber, slightly opalescent.
The dehydrated medium should be homogeneous, free-flowing and cream in color. If there are any physical changes,
discard the medium.
USES
SHIGELLA BROTH is a selective enrichment recommended by ISO 21567:2004 for the preparation and dilution of the
sample and as a selective enrichment.
Shigella is the bacterium that causes the disease shigellosis, also known as bacillary dysentery. Shigella is one of the
most easily transmitted bacterial diarrheas, since it can occur after fewer than 100 bacteria are ingested. Foods that
come into contact with human or animal waste can transmit Shigella. Thus, handling toddlers’ diapers, eating vegetables
from a field contaminated with sewage, or drinking pool water are all activities that can lead to shigellosis
Casein Peptone provide nitrogen, vitamins, minerals and amino acids essential for growth.. Dextrose is source of
vitamins, particularly the B-group. Bacteriological Agar is the solidifying agent. Dextrose is the fermentable carbohydrate
providing carbon and energy. Potassium phosphates act as a buffer system. Sodium chloride supplies essential
electrolytes for transport and osmotic balance. Polysorbate 80 is incorporated to neutralize phenols, hexachlorophene,
formalin. Novobiocin is the selective agent that inhibits most of the companion flora.
ISO 21567:2004 Standards recommends to prepare a dilution 1:10 of the sample. 25 g food sample can be added in 225
ml of Shigella Broth and homegeneize gently with an stomacher. pH may be need a readjustment to 7.0 ± 0.2 at this
point. The Shigella broth is incubated in anaerobic conditions with loose caps at 41,5 ºC for 16-20 h before streaking on
three selective media with different selectivity level: Cat. 1052 MACCONKEY (low selectivity), Cat. 1274 XLD AGAR AGAR
(Medium selectivity) and Cat. 1030 HEKTOEN ENTERIC AGAR (High selectivity).
1
LABORATORIOS CONDA, S.A.
www.condalab.com
MICROBIOLOGICAL TEST
The following results were obtained in the performance of the medium from type cultures after incubation at a
temperature of 41,5 ± 1°C and observed after 16-20 hours.
Microorganisms
Shigella sonnei ATCC 25931
Shigella flexneri ATCC 12022
Growth
Good
Good
BIBLIOGRAPHY
ISO 21567:2004 Microbiology of food and animal feeding stuffs.- Horizontal method for the detection of Shigella spp
King, S. & Metzger Appl. Microbiol. 16:577. 1968. King, S. & Metzger Appl. Microbiol. 16:579, 1968.
STORAGE
25ºC
Once opened keep powdered medium closed to avoid hydration.
2ºC
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LABORATORIOS CONDA, S.A.
www.condalab.com