Mehedinti County is splited in two sides – one for Serbia, to which is connected by Iron Gates Dam passage and the other one is related to Bulgaria, which is not connected by the Dam passage.
So, to can touch Mehedinti County, coming from Bulgaria, you can use bridge Calafat-Vidin and from there following Danube border after about 100 km to touch Drobeta Turnu Severin town.
The other way is to pass bridge Calafat-Vidin, having about 80km to Craiova, where you touch the main road between Timisoara – Drobeta Turnu Severin-Craiova-Slatina-Buchurest and to follow this road from Craiova to Drobeta Turnu Severin – about 120 km distance.