Multiplex PCR amplification of Cp. abortus , Cp. pecorum and C. burnetii references strains individually, and in all possible combinations. Lane 1: 100-bp ladder; lane 2: Cp. abortus AB7; lane 3: Cp. pecorum iB1; lane 4: C. burnetii Nine Miles; lane 5: Cp. abortus and Cp. pecorum; lane 6:Cp. abortus and C. burnetii; lane 7: Cp. pecorum and C. burnetii; lane 8: Cp. abortus, Cp. pecorum and C. burnetii; lane 9: Negative control without DNA. The sizes of the three different PCR products are shown on the left.