Ralstonia solanacearum, that causes bacterial wilt of tobacco, is a highly polyphagous bacterium. It has been occasionally observed in France but never on tobacco. It occurs mainly in tropical and subtropical countries, the Americas and Asia in particular.
 
Foliar symptoms caused by this bacterium are similar to those caused by Verticillium wilt. Leaf wilts are first unilateral, sometimes accompanied by yellowing of the lamina (figure 1). Fairly quickly, affected leaves become necrotic and dry (figure 2). One can observe yellow bands on stems which sometimes become cankerous and turn brown (figure 3). A longitudinal section of the stem shows that the vessels are brown and have dark brown to black streaks. Sometimes the pith and cortex are also affected (figure 4) as well as the roots. 
 
The identification of this systemic bacterial disease often requires laboratory analysis. Note that there is a fairly simple way to confirm your diagnosis: cut the stem of a diseased plant and put it in a humid chamber or in a water container. After a variable period of time, you will see a slimy bacterial mass of dirty white exuding from the cut. 
 
For further information about this bacterium, see the Ralstonia solanacearum fact sheet.