Bacteriocin production augments niche competition by enterococci in the mammalian gastrointestinal tract.
Kommineni Sushma,Bretl Daniel J,Lam Vy,Chakraborty Rajrupa,Hayward Michael,Simpson Pippa,Cao Yumei,Bousounis Pavlos,Kristich Christopher J,Salzman Nita H
Enterococcus faecalis is both a common commensal of the human gastrointestinal tract and a leading cause of hospital-acquired infections. Systemic infections with multidrug-resistant enterococci occur subsequent to gastrointestinal colonization. Preventing colonization by multidrug-resistant E. faecalis could therefore be a valuable approach towards limiting infection. However, little is known about the mechanisms E. faecalis uses to colonize and compete for stable gastrointestinal niches. Pheromone-responsive conjugative plasmids encoding bacteriocins are common among enterococcal strains and could modulate niche competition among enterococci or between enterococci and the intestinal microbiota. We developed a model of colonization of the mouse gut with E. faecalis, without disrupting the microbiota, to evaluate the role of the conjugative plasmid pPD1 expressing bacteriocin 21 (ref. 4) in enterococcal colonization. Here we show that E. faecalis harbouring pPD1 replaces indigenous enterococci and outcompetes E. faecalis lacking pPD1. Furthermore, in the intestine, pPD1 is transferred to other E. faecalis strains by conjugation, enhancing their survival. Colonization with an E. faecalis strain carrying a conjugation-defective pPD1 mutant subsequently resulted in clearance of vancomycin-resistant enterococci, without plasmid transfer. Therefore, bacteriocin expression by commensal bacteria can influence niche competition in the gastrointestinal tract, and bacteriocins, delivered by commensals that occupy a precise intestinal bacterial niche, may be an effective therapeutic approach to specifically eliminate intestinal colonization by multidrug-resistant bacteria, without profound disruption of the indigenous microbiota.
Prevalence of Infective Endocarditis in Enterococcus faecalis Bacteremia.
Dahl Anders,Iversen Kasper,Tonder Niels,Hoest Nis,Arpi Magnus,Dalsgaard Morten,Chehri Mahtab,Soerensen Lars L,Fanoe Soren,Junge Soeren,Hoest Ulla,Valeur Nana,Lauridsen Trine K,Fosbol Emil,Hoi-Hansen Thomas,Bruun Niels E
Journal of the American College of Cardiology
BACKGROUND:Enterococcus faecalis is the third most frequent cause of infective endocarditis (IE). Despite this, no systematic prospective echocardiography studies have examined the prevalence of IE in patients with E. faecalis bacteremia. OBJECTIVES:This study sought to determine the prevalence of IE in patients with E. faecalis bacteremia. The secondary objective was to identify predictors of IE. METHODS:From January 1, 2014, to December 31, 2016, a prospective multicenter study was conducted with echocardiography in consecutive patients with E. faecalis bacteremia. Predictors of IE were assessed using multivariate logistic regression with backward elimination. RESULTS:A total of 344 patients with E. faecalis bacteremia were included, all examined using echocardiography, including transesophageal echocardiography in 74% of the cases. The patients had a mean age of 74.2 years, and 73.5% were men. Definite endocarditis was diagnosed in 90 patients, resulting in a prevalence of 26.1 ± 4.6% (95% confidence interval [CI]). Risk factors for IE were prosthetic heart valve (odds ratio [OR]: 3.93; 95% CI: 1.76 to 8.77; p = 0.001), community acquisition (OR: 3.35; 95% CI: 1.74 to 6.46; p < 0.001), ≥3 positive blood culture bottles (OR: 3.69; 95% CI: 1.88 to 7.23; p < 0.001), unknown portal of entry (OR: 2.36; 95% CI: 1.26 to 4.40; p = 0.007), monomicrobial bacteremia (OR: 2.73; 95% CI: 1.23 to 6.05; p = 0.013), and immunosuppression (OR: 2.82; 95% CI: 1.20 to 6.58; p = 0.017). CONCLUSIONS:This study revealed a high prevalence of 26% definite IE in patients with E. faecalis bacteremia, suggesting that echocardiography should be considered in all patients with E. faecalis bacteremia.
Genome-based characterization of hospital-adapted Enterococcus faecalis lineages.
Raven Kathy E,Reuter Sandra,Gouliouris Theodore,Reynolds Rosy,Russell Julie E,Brown Nicholas M,Török M Estée,Parkhill Julian,Peacock Sharon J
Vancomycin-resistant Enterococcus faecalis (VREfs) is an important nosocomial pathogen(1,2). We undertook whole genome sequencing of E. faecalis associated with bloodstream infection in the UK and Ireland over more than a decade to determine the population structure and genetic associations with hospital adaptation. Three lineages predominated in the population, two of which (L1 and L2) were nationally distributed, and one (L3) geographically restricted. Genome comparison with a global collection identified that L1 and L3 were also present in the USA, but were genetically distinct. Over 90% of VREfs belonged to L1-L3, with resistance acquired and lost multiple times in L1 and L2, but only once followed by clonal expansion in L3. Putative virulence and antibiotic resistance genes were over-represented in L1, L2 and L3 isolates combined, versus the remainder. Each of the three main lineages contained a mixture of vancomycin-resistant and -susceptible E. faecalis (VSEfs), which has important implications for infection control and antibiotic stewardship.
Comparative genomic analysis of Enterococcus faecalis: insights into their environmental adaptations.
He Qiuwen,Hou Qiangchuan,Wang Yanjie,Li Jing,Li Weicheng,Kwok Lai-Yu,Sun Zhihong,Zhang Heping,Zhong Zhi
BACKGROUND:Enterococcus faecalis is widely studied as a common gut commensal and a nosocomial pathogen. In fact, Enterococcus faecalis is ubiquitous in nature, and it has been isolated from various niches, including the gastrointestinal tract, faeces, blood, urine, water, and fermented foods (such as dairy products). In order to elucidate the role of habitat in shaping the genome of Enterococcus faecalis, we performed a comparative genomic analysis of 78 strains of various origins. RESULTS:Although no correlation was found between the strain isolation habitat and the phylogeny of Enterococcus faecalis from our whole genome-based phylogenetic analysis, our results revealed some environment-associated features in the analysed Enterococcus faecalis genomes. Significant differences were found in the genome size and the number of predicted open reading frames (ORFs) between strains originated from different environments. In general, strains from water sources had the smallest genome size and the least number of predicted ORFs. We also identified 293 environment-specific genes, some of which might link to the adaptive strategies for survival in particular environments. In addition, the number of antibiotic resistance genes was significantly different between strains isolated from dairy products, water, and blood. Strains isolated from blood had the largest number of antibiotic resistance genes. CONCLUSION:These findings improve our understanding of the role of habitat in shaping the genomes of Enterococcus faecalis.