Abstract
BackgroundIt has been suggested that prophages in the ST398 S. aureus clone are responsible for expanding ST398's spectrum of action and increasing its ability to cause human infections. We carried out the first characterization of the various prophages carried by 76 ST398 bloodstream infection (BSI) isolates obtained over 9 years of observation.ResultsWhole-genome sequencing of 22 representative isolates showed (1) the presence of the φ3-prophage and diverse genetic features typical of animal-associated isolates (i.e., SCCmec XI element, Tn916 transposon and non φ3-prophages) in a majority of BSI isolates, (2) one BSI isolate devoid of the φ3-prophage but otherwise similar to an animal-infecting isolate, (3) 35 prophages carrying numerous genes previously associated with virulence or immune evasion in animal models of staphylococcal infections. The analysis of prophage content in all 76 BSI isolates showed an increasing prevalence of polylysogeny over time. Overall, over the course of the last 10 years, the BSI isolates appear to have acquired increasing numbers of genetic features previously shown to contribute to bacterial adaptation and virulence in animal models of staphylococcal infections.ConclusionsWe hypothesize that lysogeny has played a significant role in increasing the ability of the ST398 clone to cause infections in humans. Our findings highlight the risk that the ST398 lineage will increase its threat to public health by continuing to acquire virulence and/or multiple antibiotic-resistance genes from hospital-associated clones of Staphylococcus aureus.
Highlights
It has been suggested that prophages in the sequence type 398 (ST398) S. aureus clone are responsible for expanding ST398's spectrum of action and increasing its ability to cause human infections
Genome sequencing High-throughput sequencing technology was used to sequence the genomes of 22 ST398 isolates, including 16 bloodstream infection (BSI) isolates randomly selected from our collection, and the six isolates representative of animal-associated isolates described in previous studies [6, 12]
Multiple mobile genetic elements (MGEs), including 35 prophages were identified in the genomes of the isolates studied (Table 1, Figs. 1 and 2, Additional file 1: Table S2). φ3-prophages were the only MGEs carried by most (15/16) BSI isolates and these prophages were absent from animal-associated isolates
Summary
It has been suggested that prophages in the ST398 S. aureus clone are responsible for expanding ST398's spectrum of action and increasing its ability to cause human infections. We carried out the first characterization of the various prophages carried by 76 ST398 bloodstream infection (BSI) isolates obtained over 9 years of observation. Staphylococcus aureus sequence type 398 (ST398) is a lineage initially described in the early 2000s in colonized livestock pigs and in humans living in close contact with these animals [1, 2]. There has been a widening of the infection spectrum of these bacteria to include humans living in animal-free environments and companion and livestock animals other than pigs. ST398 has since become established as a major S. aureus clone responsible for BSIs in the analyzed area.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
