Identification of Coxiella burnetii genotypes in Croatia using multi-locus VNTR analysis

- We have genotyped Coxiella burnetii strains for the first time in Croatia.
- For the genotyping we used MLVA.
- We have identified 13 novel C. burnetii genotypes that appear to be unique to Croatia.

Although Q fever affects humans and animals in Croatia, we are unaware of genotyping studies of Croatian strains of the causative pathogen Coxiella burnetii, which would greatly assist monitoring and control efforts. Here 3261 human and animal samples were screened for C. burnetii DNA by conventional PCR, and 335 (10.3%) were positive. Of these positive samples, 82 were genotyped at 17 loci using the relatively new method of multi-locus variable number tandem repeat analysis (MLVA). We identified 13 C. burnetii genotypes not previously reported anywhere in the world. Two of these 13 genotypes are typical of the continental part of Croatia and share more similarity with genotypes outside Croatia than with genotypes within the country. The remaining 11 novel genotypes are typical of the coastal part of Croatia and show more similarity to one another than to genotypes outside the country. Our findings shed new light on the phylogeny of C. burnetii strains and may help establish MLVA as a standard technique for Coxiella genotyping.