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ICESpy009, a Conjugative Genetic Element Carrying mef(E) in Streptococcus pyogenes
Maria Del Grosso1, Romina Camilli2, Ermanno Rizzi3
1Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Rome, Italy maria.delgrosso@iss.it.
Antimicrobial Agents and Chemotherapy
|April 13, 2016
Summary
Macrolide resistance in Streptococcus pyogenes is rare but linked to the mega element. Researchers discovered a novel mobile genetic element, ICESpy009, carrying mega and capable of transferring resistance between bacteria.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Macrolide resistance, mediated by the mega element (mef(E)/mel), is prevalent in Streptococcus pneumoniae but uncommon in Streptococcus pyogenes.
- Previous findings in S. pyogenes indicated mega was part of the Tn2009 composite genetic element, conferring erythromycin and tetracycline resistance.
Purpose of the Study:
- To investigate the genetic context of the mega element in S. pyogenes isolates lacking other resistance determinants.
- To characterize a novel integrative and conjugative element (ICE) carrying mega in S. pyogenes.
Main Methods:
- Whole-genome sequencing of an S. pyogenes isolate (MB56Spyo009) to identify the genetic element carrying mega.
- Characterization of the novel ICE, including its size, open reading frames (ORFs), and integration site.
- PCR mapping to detect similar ICEs in other isolates and identify their integration sites.
- Conjugation experiments to assess the transferability of macrolide resistance.
Main Results:
- Identification of a novel 55 kb composite ICE, designated ICESpy009, belonging to the ICESa2603 family, carrying the mega element.
- ICESpy009 was found integrated into the hylA gene, a new integration site for this ICE family.
- A novel cluster of accessory resistance genes was identified within the mega-enclosing region of ICESpy009.
- Similar ICEs were detected in five other isolates, with integration sites including hylA and the typical rplL site.
- ICESpy009 demonstrated the ability to transfer macrolide resistance via conjugation to both S. pyogenes and S. pneumoniae.
Conclusions:
- The study identified a novel ICE, ICESpy009, in S. pyogenes carrying the mega element and novel accessory resistance genes.
- This ICE utilizes a new integration site (hylA) within S. pyogenes, although the typical rplL site was also observed.
- The findings provide the first evidence of mega's transferability from S. pyogenes, highlighting a potential mechanism for the spread of macrolide resistance.
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