Loss of TSS1 in hypervirulent Coxiella burnetii 175, the causative agent of Q fever in French Guiana

In French Guiana, the unique Coxiella burneta circulating genotype 17 causes 24% of community-acquired pneumonia, the highest prevalence ever described. To explain this unusual virulence, we performed a comparative genomic analysis of strain Cb175, which was isolated from a patient from French Guiana. Cb175 has a greater number of mutations in genes involved in metabolism compared with the Nine Mile I strain. We found a 6105 bp fragment missing in Cb175, which corresponds to the Type 1 secretion systems (T1SS) hlyCABD operon region. This deletion was detected by a specific qPCR in the 8 other strains available from this territory an in none of 298 C.burnetii strains from other areas and other genotypes (8/8 vs 0/298, Fisher's exact test, p < 0.0000001). Loss of genes implicated in secretion systems has been observed in other epidemic bacterial strains. Thus, the virulence of Cb175 may be linked to this genome reduction. (C) 2015 Elsevier Ltd. All rights reserved.