**5.1 Culture methods**

Culture method in identification of *Salmonellas* is conducted with pre-enrichment and selective medium planting.

Identification studies are same regardless from the source of the culture. Variety of mediums used in the culture may depend on characteristics of the sample examined. Especially when number of *Salmonellas* are less and other organisms are more, very careful study is required. If extra clinical samples are processed such as heating, drying and radiation or they are frozen or kept for a long time or pH level is low although clinical samples are examined as fresh, nonselective pre-enrichment culture is applied. Because these processes weakened *Salmonellas* and made them semi-selective. The purpose is to provide this kind of bacteria to their normal reproduction period before contacting inhibitor substances. Because selective substances may make a toxic effect for "weakened" *Salmonellas* . While enrichment bouillon culture facilitates reproduction of *Salmonellas* , it also provides inhibiting or decreasing effect for reproduction of other organisms. Accompaniment organisms mainly include coliforms, proteus species and pseudomonas. As the proportion of these organisms is more than *Salmonellas* in particular, selective enrichment process gains importance. However, there are differences between *Salmonella* types in terms of inhibitor substance sensitivity. Therefore, it is impossible to say which selective enrichment bouillon is the most suitable definitely for today. Selective agar mediums generally include inhibitor substances and an inhibitor system. Indicator system either changes the color of colonies or the color of agar area around the colony changes. Thus, it helps to identify suspicious *Salmonella* colonies.

The following Agar Mediums are used in various countries.

Brillant green agar Brillantgreen Sulphadiazine agar Brillant Green Mac Conkey agar Desoksicholate Citrate agar *Salmonella* -Shigella Agar,(SS) Bismuth Sulphite agar EMB AGAR ENDO AGAR

Samples are taken into non-selective enrichment medium (lactone bouillon) according to their clinical or extra clinical sample characteristics and incubates at 35-37 °C for 24 to 48 hours, then 1 ml from them is taken and taken into selective enrichment medium and (Selenite F, tetrathionate bouillon) A and incubated at 35-37 °C for 24 hours.

### **5.1.1 Non selective enrichment**


Isolation and Identification of Salmonellas from Different Samples 141

It is colorless and transparent. Coliform organisms precipitate bile salts in the medium.

*Salmonella* colonies reproduced near coliforms dissolve precipitated area (*Figure 5).* 

**5.1.3.2 Appearance of typical** *Salmonella* **colonies in mac conkey agar** 

Fig. 5. Appearance of typical *Salmonella* colonies in Mac Conkey agar

Some of *Salmonellas* make colonies of which the centre is black (*Figure 6)*.

Fig. 6. Appearance of *Salmonella* colonies in *Salmonella* – Shigella agar (SS)

**5.1.3.3 Appearance of** *Salmonella* **colonies in** *Salmonella* **– Shigella agar (SS)** 

Typical *Salmonella* colonies are colorless or very light pink, opaque or semi-transparent.

3. At this time, a loop full of the sample is taken and planting to selective agar medium is performed.
