Purpose: The objective of this project was to analyze the genome of the recently sequenced strain C. jejuni 11601MD isolated from turkeys in order to identify plasmid-associated sequences and to characterize possible conjugative plasmids harboring antibiotic resistance determinants.
Methods: Total genomic DNA of C. jejuni 11601MD was sequenced at the Genome Core Facility at Duke University. Annotation of the genome sequence was done using GAMOLA (Altermann and Klaenhammer, 2003), taking into account all Campylobacter genomes sequenced to date. compACTor (Altermann, 2012) and the ARTEMIS Comparison Tool (ACT, Carver et al., 2005) were used to determine presence and comparative genomic location of sequences homologous to the tetracycline resistance gene tet(O) in the different genomes.
Results: A novel plasmid (44,095 nts) harboring tet(O) was identified. Further analysis of the sequence revealed the presence of a putative aminoglycoside transferase gene, highly similar to kanamycin resistance genes in other organisms and located downstream of tet(O). Several genes putatively involved in conjugative transfer were identified on the plasmid. A functional genome distribution (FGD) analysis, based on the plasmid ORFeomes was performed with the newly identified C. jejuni plasmid and 27 other published Campylobacter plasmids using compACTor, MEGA, and ACT. The FGD results suggested that the plasmids clustered in two well differentiated groups but were highly conserved within each group. The plasmid of C. jejuni 11601MD was clustered together with other tet(O)-harboring plasmids in one of these groups. Complementarily, antibiotic susceptibility tests performed on C. jejuni 11601MD confirmed the resistance to both kanamycin and tetracycline.
Significance: These findings will contribute to a better understanding of the distribution of potentially self-mobilizing plasmids harboring antibiotic resistance determinants in Campylobacter spp. Strain specific sequences of the C. jejuni 11601MD plasmid can be utilized to develop tools for detection of similar plasmids in C. jejuni from turkeys and other sources.