Occurrence of (O/M/O) Mosaic Gene in Tetracycline-Resistant .

is one of the most important microorganisms responsible for foodborne diseases in the EU. In this study, we investigated resistance to tetracycline in 139 and samples isolated from human clinical cases. From these, 110 were resistant to tetracycline, with MIC (minimal inhibitory concentration) varying in a range of 1 to >512 μg/mL, and 109 (78.4%) carried (O), a gene that confers resistance to tetracycline through the expression of a protein that confers protection to the ribosome. Amongst the tetracycline-resistant isolates, one (HCC30) was the only -negative sample, presenting an MIC of 256 μg/mL. Instead, the mosaic gene (O/M/O) was found in HCC30 and, as far as we know, this is the first description of this chimeric gene originating from homologous recombination between (O) and (M). The previously described mosaic gene (O/32/O), also found in , presents a chimeric structure very similar to that of (O/M/O), affecting domains II and III of encoded proteins distantly related to the elongation factor G (EF-G). The (O/M/O) mosaic gene has been found in nucleotide databases in several genomes of isolated from different origins, indicating its frequent acquisition, even though it can be undetected through screening by PCR with specific (O) primers. In this work, we address the improvement of classical PCR to efficiently diagnose the most prevalent tetracycline resistance determinants in , including (O/M/O), which should be taken into account in the optimization of campylobacteriosis treatments.