**6.1 Isolation of salmonella**

*Salmonella* Typhi, Paratyphi A, B, C are preferably isolated in the blood and feces of typhoid (Dumas, 1958). The *Salmonella* that cause food poisoning or acute gastroenteritis are still being sought in the feces and in food. The detection of *Salmonella* may be direct (bacteriological method) or indirect (serological technique) according to (Humbert et al., 1998). The microbiological analysis of a food is to highlight the microorganisms responsible for the alteration of merchantability and / or health. The analytical methods vary with the type of food, the potential danger it presents, and conservation features, consumption (raw or cooked) and the desired type of germ. Food is supportive environments for the development of a multitude of germs, some of which are pathogenic. Faced with the task of

Use Thyme Essential Oils for the Prevention of Salmonellosis 311

2. The search for differential characters requires pure cultures. Used for this purpose, the reduced rack of le Minor which is a set of five settings: the mid-Hajna Klinger; the Simmons citrate medium; the lysine iron or Taylor medium; the tryptophan-urea

**The mid-Hajna Kliger** (solid medium): The mid-Hajna Kliger has a carmine red color. This medium is only valid for the fermentative bacteria. It is part of the study of carbohydrate metabolism. **The lysine iron medium** or mid-Taylor (purple), enriched with L-lysine and contains low concentrations of glucose. **The Simmons citrate** medium (green), contains citrate as the sole carbon source. Bacteria that are able to use this carbon source, will grow on this agar and cause a pH change at the origin of the middle turn blue. Remains green agar for strains citrate (-). **The urea-indole medium** (liquid medium), the urea -indole or urea -tryptophan medium, is a medium orange, made up of urea and tryptophan. It allows for three enzymatic activities of protein metabolism, including urease, tryptophanase and tryptophan deaminase. **The medium with glycerol** (liquid medium), this medium is green; it is very often added to other settings of Le Minor rack. It helps to distinguish Citrobacter and Salmonella genus. Citrobacter degrades glycerol by causing acidification of the medium (turns to yellow) and Salmonella do not degrade it, the green color is maintained. In summary, the general biochemical characteristics of most serotypes isolated from humans

Lactose (-), ONPG (-)(orthonitrophenyl-β-D-galactopyranoside), H2S (+), gas (glucose)

 LDC (+)(lysine decarboxylase), ODC (+)(ornithine decarboxylase), ADH (-)(arginine dihydrolase), urease (-), TDA (-)(tryptophane deaminase), indole (-), gelatinase (-)

No production of acetoin (Voges-Proskauer test (-)), RM (+)(methyl red energy source),

It should be noted that there are important exceptions. The serotype Typhi does not decarboxylated ornithine, does not grow on a medium composed of Simmons citrate, it is agazogene and produces only trace amounts of H2S. Serotype Paratyphi A does not decarboxylated lysine and does not grow on Simmons citrate medium. Finally, Salmonella Paratyphi A, Choleraesuis, and Gallinarum do not produce H2S. In this case, the settlements will not have black centers on isolation media consisting of iron citrate and sodium

The economic importance of these diseases is considerable. In the U.S., economists have estimated the annual costs of salmonellosis between 400 million and U.S. \$ 3.5 billion for the entire U.S. economy. They took into account the medical costs and lost productivity (Frenzen et al. 1999; Sarwari et al., 2001). Europe, whereas 95% of salmonellosis is food borne, annual costs range between 560 million and 2.8 billion euros. A single case of salmonellosis is estimated, in turn, to a value between EUR 24 and EUR 3.8 million. This estimate refers to cases where the patient dies of infection (European Parliament and Council of the European Union, 2001). In Africa, there are no data on the annual cost of

Simmons citrate (-), adonitol (-), glycerol (-), galacturonate (-).

medium and mannitol nitrate mobility medium.

characters.

and warm-blooded animals are:

thiosulfate (eg, XLD, Hektoen, SS).

**7. Economic importance and societal** 

(+);

DNase (-);

salmonellosis.

and fermentation of glucose are sufficient to encourage the search for differential

finding a pathogenic bacteria specie in very small proportion of a product heavily contaminated with the bacteria most various conventional methods of analysis, sampling and isolation have been proposed. Several standards govern the detection of Salmonella in food hygiene (Humbert et al., 1998): the horizontal standards applicable to all types of products (ISO6579 December 1993) at international level and industry standards specific to one type of product (NF V59 - 109 for edible gelatin). The detection of Salmonella in a food according to ISO 6579 has four key steps: The pre-enrichment; Enrichment; Isolation and Biochemical and serological identification.
