Novel Tn916-like elements confer aminoglycoside/macrolide co-resistance in clinical isolates of Streptococcus gallolyticus ssp. gallolyticus. (9th February 2018)

• Record Type: Journal Article
• Authors: Kambarev, Stanimir; Pecorari, Frédéric; Corvec, Stéphane
• Is Part Of: Journal of antimicrobial chemotherapy. Volume 73:Number 5(2018)
• Page Start: 1201
• Page End: 1205
• Publication Date: 2018-02-09
• Subjects: Anti-infective agents -- Periodicals; Chemotherapy -- Periodicals; 615.58
• DOI: 10.1093/jac/dky016
• Languages: English
• ISSNs: 0305-7453

Abstract

Abstract: Background: Streptococcus gallolyticus ssp. gallolyticus ( Sgg ) is a commensal bacterium and an opportunistic pathogen. In humans it has been clinically associated with the incidence of colorectal cancer (CRC) and epidemiologically recognized as an emerging cause of infective endocarditis (IE). The standard therapy of Sgg includes the administration of a penicillin in combination with an aminoglycoside. Even though penicillin-resistant isolates have still not been reported, epidemiological studies have shown that this microbe is a reservoir of multiple acquired genes, conferring resistance to tetracyclines, aminoglycosides, macrolides and glycopeptides. However, the underlying antibiotic resistance mobilome of Sgg remains poorly understood. Objectives: To investigate the mobile genetic basis of antibiotic resistance in multiresistant clinical Sgg . Methods: Isolate NTS31106099 was recovered from a patient with IE and CRC at Nantes University Hospital, France and studied by Illumina WGS and comparative genomics. Molecular epidemiology of the identified mobile element(s) was performed using antibiotic susceptibility testing (AST), PCR, PFGE and WGS. Mobility was investigated by PCR and filter mating. Results: Two novel conjugative transposons, Tn 6263 and Tn 6331, confer aminoglycoside/macrolide co-resistance in clinical Sgg . They display classical family Tn 916 /Tn 1545 modular architecture and harbour an aph (3′)-III→ sat4 → ant (6)-Ia→ erm (B) multiresistance gene cluster, related to pRE25 of Enterococcus faecium . These and/or closely related elements are highly prevalent among genetically heterogeneous clinical isolates of Sgg . Conclusions: Previously unknown Tn 916 -like mobile genetic elements conferring aminoglycoside/macrolide co-resistance make Sgg, collectively with other gut Firmicutes such as enterococci and eubacteria, a potential laterally active reservoir of these antibiotic resistance determinants among the mammalian gastrointestinal microbiota.