FACTS & IDENTIFICATION
SALMONELLA SPP.
What is it?
Salmonella
is
a
rod-shaped,
motile,
on-spore-forming and Gram-negative bacterium.
The Salmonella family includes over 2,300
serotypes of bacteria.
For over 100 years, the bacteria have been known
to cause illness. They were discovered by an
American scientist named Salmon, after whom
they are named.
There are many different kinds of Salmonella
bacteria. Salmonella serotype Typhimurium and
Salmonella serotype Enteritidis are the most
common.
The bacteria grow optimally at 37ºC and can
catabolize D_glucose and other carbohydrates
by producing acid and gas.
It causes Salmonellosis. S. typhi and S. paratyphi
A, B, and C produce typhoid and typhoid-like
fever in humans.
Salmonella is estimated to cause about 1.2
million illnesses in the United States, with about
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hospitalizations and 450 deaths. Because many milder
cases are not diagnosed or reported, the actual
number of infections may be twenty-nine or more
times greater.
What are the symptoms of Salmonellosis?
Diarrhea, fever, and abdominal cramps.
They develop 12 to 72 hours after infection, and the
illness usually lasts from 4 to 7 days.
What causes salmonellosis?
Food contaminated with Salmonella may occur
during food processing or food handling.
Beef, poultry, milk, and eggs are the foods most
prone to be infected with Salmonella, but
vegetables may also be contaminated. However,
contaminated foods usually look and smell normal.
Pets may carry Salmonella bacteria in their
intestines, so their feces are a potential concern.
Certain pets, such as turtles, snakes and other
reptiles, and chicken and other birds, are more
likely to carry it.
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How can we prevent it?
Avoid eating high-risk foods, including raw or
lightly cooked eggs, undercooked ground beef or
poultry, and unpasteurized milk.
Keep food properly refrigerated before cooking.
Wash your hands after contact with animals, their
food or treats, or their living environment.
How can we identify it?
A variety of culture and rapid methods are
available for the detection of Salmonella Spp. in
foods.
The most commonly used culture reference
method world-wide for the detection of
Salmonella spp is UNE EN ISO 6579:2003 – This
international regulation specifies a horizontal
method for the detection of Salmonella, including
Salmonella Typhi and Salmonella Paratyphi in
food and animal stuff.
Safety
Several countries follow the CDC/NIH biosafety
recommendations indicated in "Biosafety in
Microbiological and Biomedical Laboratories",
4th Edition, 1999 (ref. 4) which recommend
Biosafety Level 2 practices for all Salmonella,
except S. Typhi. For S. Typhi they recommend
Biosafety Level 2 practices for activities with
clinical materials and cultures; and Biosafety
Level 3 practices for activities that can generate
aerosols or for activities involving high volumes
of organisms.
ISO UNE EN ISO 6579:2003/A1:2007
Pre-enrichment - is the step where the sample is
enriched in a non-selective nutrient medium,
enabling the damaged Salmonella cells to be
repaired, and achieving a stable physiological
condition.
Selective enrichment - is achieved by using a
culture medium combining two conditions: on the
one hand it will increase the Salmonella
populations and, on the other, inhibit other
microorganisms present in the sample.
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28850 - Torrejón de Ardoz, Madrid - SPAIN
Selective isolation - this point follows on directly from
the above. Here selective media, which restrict the
growth of types other than Salmonella and which
allow the visual recognition of suspicious colonies, are
used.
Confirmation - this step allows the generic
identification of Salmonella cultures and the
elimination of false suspicious cultures.
PREENRICHEMENT
Cat. 1402 Buffered Peptone Water (ISO 6579, ISO 22964)
SELECTIVE ENRICHMENT
Cat. 1174 Rappaport Soy Broth (Vasiliadis)
Cat. 1173 Muller Kauffman Broth Base with Brillian Green
and Novobiocin
SELECTIVE ISOLATION
Cat. 1274 XLD Agar (ISO 6579)
Another selective media of choice:
Cat. 1143 Brillian Green Agar
Cat. 1030 Hektoen EntericAgar
Cat.1122 Salmonella Chromogenic Agar
CONFIRMATION
Cat. 1172 Triple Sugar Iron Agar (TSI) (ISO 6579)
Cat.1110 Urea Agar Base (ISO 6579)
Cat. 1176 Lysine Decarboxile Broth (ISO 6579)
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Biochemical Profile
SALMONELLA STRAIN
S. Typhi
S. Paratyphi
S. Paratyphi B
S. Paratyphi C
Others
+
+
+
-
+
+
-
+
+
+
+
-
+
+
+
+
-
+
+
+
+
-
TSI Glucose (acid formation)
TSI Glucose (acid formation)
TSI Lactose
TSI sucrose
TSI hydrogen sulfide
Urea splitting
B- galactosidase reaction
Voges Proskauer reaction
Indole reaction
BIBLIOGRAPHY
Food-Borne Pathogenic Microorganisms and Natural Toxins Handbook: “The Bad Bug Book” U.S. FDA/CFSAN. Center for Food Safety and Applied Nutrition,
Food and Drug Administration, College Park , 2003
.
Rappaport F., Konforti N. and Navon B. (1 956) J. ClinPathol., 9,261.Peterz M. Wiberg C. and Norberg P. (1989) J. Appl. Bact. 66: 523-528.
UNE-EN-ISO 6579.Food Microbiology for human consumption and Animal Feed.Horizontal Method for the detection of Salmonella spp. ISO19250 Water
quality-Detection of Salmonella spp
Antle, J.M., 1995. Choice and Efficiency in Food Safety Policy.The AEI Press, Washington, DC.
NMKL method no. 71, 2nd ed., 1999: Salmonella. Detection in food. Nordic committee on food analysis, Oslo, Norway
www.condalab.com
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28850 - Torrejón de Ardoz, Madrid - SPAIN
Phone. +34 91 761 02 00
Fax +34 91 656 82 28