Maybe this can give you some ideas about the selection procedure: http://www.sciencedirect.com/science/article/pii/S0006291X74803244
I'm not sure if the use of citrate is a good option, since I remember Escherichia coli gives a negative result in citrate test (which means lacks citritase and is not able to use citrate as sole source of carbon). However, it is able to grow on succinate... maybe that would be a good option for the screening.