Identification by genotyping of a commercial antigen preparation as the source of a laboratory contamination with Coxiella burnetii and as an unexpected rich source of control DNA.

By performing genotyping, a laboratory contamination involving Q fever was traced back to the antigen preparation used in a commercially available complement fixation test. It was established that such antigen preparations contain relatively high loads of DNA/RNA, making them potential sources of contamination but also convenient preparations for control material.