Prevalence, diversity and transferability of the Tn916-Tn1545 family ICE in oral streptococci

Abstract

<i>Background</i>: The Tn<i>916</i>-Tn<i>1545</i> family of Integrative Conjugative Elements (ICE) are mobile genetic elements (MGEs) that play a role in the spread of antibiotic resistance genes. The Tn<i>916</i> harbors the tetracycline resistance gene <i>tet</i>(M) and it has been reported in various bacterial species. The increase in the levels of tetracycline resistance among oral streptococci is of great concern primarily due to the abundance of these species in the oral cavity and their ability to act as reservoirs for antibiotic resistance genes.<br><br>

<i>Methods</i>: In the current study, we screened 100 Norwegian clinical oral streptococcal isolates for the presence and diversity of the Tn<i>916</i>-Tn<i>1545</i> family. In addition, we investigated the transferability the elements, and the associated transfer frequencies.<br><br>

<i>Results</i>: We observed that 21 isolates harboured the Tn<i>916</i>-Tn<i>1545</i> family and that two of these elements were the novel Tn<i>6815</i> and Tn<i>6816</i>. The most prevalent member of the Tn<i>916</i> -Tn<i>1545</i> family observed in the Norwegian clinical oral streptococcal isolates was the wild type Tn<i>916</i>.Conclusion: The detection of other members of this family of ICE and varying transfer frequencies suggests high versatility of the Tn<i>916</i> element in oral streptococci in Norway.