Title: 1128 - Probing the Streptococcus anginosus genome to understand its invasive potential


Yasser, Abdelrahman AbdelRahman (Presenter)

Amanda Brenner, Portland State University
Rahul Raghavan, Portland State University
Justin Merritt, Oregon Health & Science University


Objectives: Streptococcus anginosusis a typical member of the oral microbiome and one of the most common sources of both odontogenic and extraoral abscesses, in fact oral abscess is the top nontraumatic oral injury in children. As such, it is also the most frequent source of life-threatening streptococcal invasive disease. However, it is currently unknown why certain strains are invasive. Using comparative genomics of sequenced strains of S. anginosus, our aim wasto identify putative loci responsible for its invasive potential.

Methods: 10 clinical isolates of S. anginosus (5 invasive and 5 abscess) were sequenced using Illumina HiSeq, annotated using the NCBI Annotation Pipeline, and then analyzed together with other available S. anginosus genome data to distinguish the core/non-core genome and all mobile genetic elements (MGE).

Results: 392 MGE were identified among all published S. anginosus genomes. Of these, 255 were tyrosine integrase-based MGEs (T-MGEs), 82 were serine recombinase-based MGEs (S-MGEs), 31 were DDE transposase-based elements, and 24 were phages. The identification of individual S-MGEs is particularly complex, as groups of 4-6 distinct S-MGEs often integrate into a single locus by targeting each others’ traG and/or maff2 genes. The boundaries of nearly all identified T-MGEs were mapped and found to target >15 unique genes, whereas S-MGEs targeted an additional >10 genes. At least 5 novel, previously undescribed MGE targets were identified. Two S. anginosus strains harbored 3 phages per genome, while 3 strains harbored 2 phages, and 12 strains harbored a single phage. Comparative analysis of the non-core genes identified several genes uniquely associated with the invasive isolates. As part of this study, we also developed a new strategy to greatly simplify gap closure between contigs during genome assembly.

Conclusions: Invasive S. anginosus strains have acquired a plethora of unique mobile genetic elements during their evolution. Such elements are important for pathogenesis and may be a key predictor of invasive potential between strains.

Student Presenter

This abstract is based on research that was funded entirely or partially by an outside source:
NIH 1R35DE028252-01

Disclosure Statement:
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: none