Simultaneous differential detection of Chlamydophila abortus, Chlamydophila pecorum and Coxiella burnetii from aborted ruminant's clinical samples using multiplex PCR

BACKGROUND: Chlamydiosis and Q fever, two zoonosis, are important causes of ruminants' abortion around the world. They are caused respectively by strictly intracellular and Gram negative bacterium Chlamydophila abortus (Cp. abortus) and Coxiella burnetii (C. burnetii). Chlamydophila pecorum (Cp. pecorum) is commonly isolated from the digestive tract of clinically inconspicuous ruminants but the abortive and zoonotic impact of this bacterium is still unknown because Cp. pecorum is rarely suspected in abortion cases of small ruminants. We have developed a multiplex PCR (m-PCR) for rapid simultaneous differential detection of Cp. abortus, Cp. pecorum and C. burnetii in clinical samples taken from infected animals. RESULTS: Specific PCR primers were designed and a sensitive and specific m-PCR was developed to detect simultaneously, in one tube reaction, three specific fragments of 821, 526 and 687-bp long for Cp. abortus, Cp. pecorum and C. burnetii respectively. This m-PCR assay was performed on 253 clinical samples taken from infected ruminant's flocks that have showed problems of abortion diseases. Thus, 67 samples were infected by either one of the three pathogens: 16 (13 vaginal swabs and 3 placentas) were positive for Cp. abortus, 2 were positive for Cp. pecorum (1 vaginal swab and 1 placenta) and 49 samples (33 vaginal swabs, 11 raw milks, 4 faeces and 1 placenta) were positive for C. burnetii. Two vaginal swabs were m-PCR positive of both Cp. abortus and C. burnetii and none of the tested samples was shown to be infected simultaneously with the three pathogens. CONCLUSION: We have successfully developed a rapid multiplex PCR that can detect and differentiate Cp. abortus, Cp. pecorum and C. burnetii; with a good sensitivity and specificity. The diagnosis of chlamydiosis and Q fever may be greatly simplified and performed at low cost. In addition, the improvement in diagnostic techniques will enhance our knowledge regarding the prevalence and the pathogenetic significance of Q fever and chlamydiosis.