scholarly journals Virulence of Enterococcus faecalis dairy strains in an insect model: the role of fsrB and gelE

Microbiology ◽  
2009 ◽  
Vol 155 (11) ◽  
pp. 3564-3571 ◽  
Author(s):  
Frédéric Gaspar ◽  
Neuza Teixeira ◽  
Lionel Rigottier-Gois ◽  
Paulo Marujo ◽  
Christina Nielsen-LeRoux ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Virulence Factors ◽  
Enterococcus Faecium ◽  
Virulence Genes ◽  
Galleria Mellonella ◽  
Deletion Mutants ◽  
Enterococcus Durans ◽  
Cell Functions ◽  
Negative Phenotype

Despite the existence of various virulence factors in the Enterococcus genus, enterococcal virulence is still a debated issue. A main consideration is the detection of the same virulence genes in strains isolated from nosocomial or community-acquired infections, and from food products. The goal of this study was to evaluate the roles of two well-characterized enterococcal virulence factors, Fsr and gelatinase, in the potential virulence of Enterococcus faecalis food strains. Virulence of unrelated Enterococcus isolates, including dairy strains carrying fsr and gelE operons, was compared in the Galleria mellonella insect model. E. faecalis dairy strains were able to kill larvae and were as virulent as strain OG1RF, one of the most widely used for virulence studies. In contrast, Enterococcus durans and Enterococcus faecium strains were avirulent or poorly virulent for G. mellonella. To evaluate the role of fsrB and gelE in virulence of E. faecalis dairy strains, both genes were deleted independently in two strains. The ΔfsrB and ΔgelE deletion mutants both produced a gelatinase-negative phenotype. Although both mutations significantly attenuated virulence in G. mellonella, the ΔfsrB strains were more strongly attenuated. These results agree with previous findings suggesting the involvement of fsrB in the control of other cell functions relevant to virulence. Our work demonstrates that the presence of functional fsrB, and to a lesser extent gelE, in dairy enterococci should be considered with caution.

Detection of virulence factors in high-level gentamicin-resistant Enterococcus faecalis and Enterococcus faecium isolates from a Tunisian hospital

2007 ◽  
Vol 53 (3) ◽  
pp. 372-379 ◽  
Author(s):  
N. Klibi ◽  
K. Ben Slama ◽  
Y. Sáenz ◽  
A. Masmoudi ◽  
S. Zanetti ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Virulence Factors ◽  
Enterococcus Faecium ◽  
Biofilm Formation ◽  
Virulence Genes ◽  
Virulence Gene ◽  
Gelatinase Activity ◽  
Genes Encoding ◽  
High Level

Phenotypic and genotypic determination of virulence factors were carried out in 46 high-level gentamicin-resistant (HLGR) clinical Enterococcus faecalis (n = 34) and Enterococcus faecium (n = 12) isolates recovered from different patients in La Rabta Hospital in Tunis, Tunisia, between 2000 and 2003 (all these isolates harboured the aac(6′)–aph(2″) gene). The genes encoding virulence factors (agg, gelE, ace, cylLLS, esp, cpd, and fsrB) were analysed by PCR and sequencing. The production of gelatinase and hemolysin, the adherence to caco-2 and hep-2 cells, and the capacity for biofilm formation were investigated in all 46 HLGR enterococci. The percentages of E. faecalis isolates harbouring virulence genes were as follows: gelE, cpd, and ace (100%); fsrB (62%); agg (56%); cylLLS (41.2%); and esp (26.5%). The only virulence gene detected among the 12 HLGR E. faecium isolates was esp (58%). Gelatinase activity was detected in 22 of the 34 E. faecalis isolates (65%, most of them with the gelE+–fsrB+ genotype); the remaining 12 isolates were gelatinase-negative (with the gelE+–fsrB– genotype and the deletion of a 23.9 kb fragment of the fsr locus). Overall, 64% of the cylLLS-containing E. faecalis isolates showed β-hemolysis. A high proportion of our HLGR E. faecalis isolates, in contrast to E. faecium, showed moderate or strong biofilm formation or adherence to caco-2 and hep-2 cells.

scholarly journals Mechanism for Sortase Localization and the Role of Sortase Localization in Efficient Pilus Assembly in Enterococcus faecalis

2009 ◽  
Vol 191 (10) ◽  
pp. 3237-3247 ◽  
Author(s):  
Kimberly A. Kline ◽  
Andrew L. Kau ◽  
Swaine L. Chen ◽  
Adeline Lim ◽  
Jerome S. Pinkner ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Virulence Factors ◽  
Transmembrane Helix ◽  
Spatial Relationship ◽  
Sortase A ◽  
Aggregation Substance ◽  
Retention Signal ◽  
Positively Charged ◽  
Pilus Assembly

ABSTRACT Pathogenic streptococci and enterococci primarily rely on the conserved secretory (Sec) pathway for the translocation and secretion of virulence factors out of the cell. Since many secreted virulence factors in gram-positive organisms are subsequently attached to the bacterial cell surface via sortase enzymes, we sought to investigate the spatial relationship between secretion and cell wall attachment in Enterococcus faecalis. We discovered that sortase A (SrtA) and sortase C (SrtC) are colocalized with SecA at single foci in the enterococcus. The SrtA-processed substrate aggregation substance accumulated in single foci when SrtA was deleted, implying a single site of secretion for these proteins. Furthermore, in the absence of the pilus-polymerizing SrtC, pilin subunits also accumulate in single foci. Proteins that localized to single foci in E. faecalis were found to share a positively charged domain flanking a transmembrane helix. Mutation or deletion of this domain in SrtC abolished both its retention at single foci and its function in efficient pilus assembly. We conclude that this positively charged domain can act as a localization retention signal for the focal compartmentalization of membrane proteins.

scholarly journals SlyA Is a Transcriptional Regulator Involved in the Virulence of Enterococcus faecalis

2011 ◽  
Vol 79 (7) ◽  
pp. 2638-2645 ◽  
Author(s):  
Charlotte Michaux ◽  
Maurizio Sanguinetti ◽  
Fany Reffuveille ◽  
Yanick Auffray ◽  
Brunella Posteraro ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Galleria Mellonella ◽  
Peritoneal Macrophages ◽  
Bacterial Virulence ◽  
Transcriptional Analysis ◽  
Infection Model ◽  
Wild Type ◽  
Content Type ◽  
Wild Type Parent

ABSTRACTPhylogenetic analysis of the crystal structure of theEnterococcus faecalisSlyA (EF_3002) transcriptional factor places it between the SlyA and MarR regulator subfamilies. Proteins of these families are often involved in the regulation of genes important for bacterial virulence and stress response. To gather evidence for the role of this putative regulator inE. faecalisbiology, we dissected the genetic organization of theslyA-EF_3001 locus and constructed aslyAdeletion mutant as well as complemented strains. Interestingly, compared to the wild-type parent, the ΔslyAmutant is more virulent in an insect infection model (Galleria mellonella), exhibits increased persistence in mouse kidneys and liver, and survives better inside peritoneal macrophages. In order to identify a possible SlyA regulon, global microarray transcriptional analysis was performed. This study revealed that theslyA-EF_3001 locus appears to be autoregulated and that 117 genes were differentially regulated in the ΔslyAmutant. In the mutant strain, 111 were underexpressed and 6 overexpressed, indicating that SlyA functions mainly as an activator of transcription.

scholarly journals Incidence of virulence determinants in clinical Enterococcus faecium and Enterococcus faecalis isolates collected in Sardinia (Italy)

2003 ◽  
Vol 52 (6) ◽  
pp. 491-498 ◽  
Author(s):  
I. Duprè ◽  
S. Zanetti ◽  
A. M. Schito ◽  
G. Fadda ◽  
L. A. Sechi
Keyword(s):  
Enterococcus Faecalis ◽  
Enterococcus Faecium ◽  
Virulence Genes ◽  
Protein Gene ◽  
Surface Protein ◽  
Virulence Determinants ◽  
Colonization Factor ◽  
Aggregation Substance ◽  
Epithelial Cell Lines ◽  
Surface Protein Gene

Enterococci are widely distributed in the environment; within the human body, they are normal commensals of the oral cavity, gastrointestinal tract and vagina. In recent years, enterococci have become one of the most frequent causes of acquired nosocomial infections worldwide. The molecular mechanism of virulence of these bacteria is still not completely understood. The aims of this work were to characterize phenotypically 47 isolates of Enterococcus faecalis and Enterococcus faecium collected in Sardinia (Italy) by their abilities to adhere to different epithelial cell lines (Vero and Caco-2 cells) and to associate their phenotypes with the presence of known virulence genes detected within their genomes by PCR. The following genes were amplified: AS (aggregation substance), esp (surface protein gene), ace (accessory colonization factor), efaA (E. faecalis endocarditis antigen) and gelE (gelatinase). The virulence genes were detected in E. faecalis isolates only, with the exception of esp, which was found in both species. The phenotypic and genotypic results were also compared with the susceptibility of isolates to various antibiotics.

scholarly journals Incidence of Virulence Factors and Antibiotic Resistance among Enterococci Isolated from Food

2001 ◽  
Vol 67 (9) ◽  
pp. 4385-4389 ◽  
Author(s):  
Charles M. A. P. Franz ◽  
Albrecht B. Muscholl-Silberhorn ◽  
Nuha M. K. Yousif ◽  
Marc Vancanneyt ◽  
Jean Swings ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Enterococcus Faecalis ◽  
Virulence Factors ◽  
Enterococcus Faecium ◽  
Antibiotic Susceptibility ◽  
Virulence Determinants ◽  
Virulence Traits

ABSTRACT The incidence of virulence factors among 48 Enterococcus faecium and 47 Enterococcus faecalis strains from foods and their antibiotic susceptibility were investigated. No strain was resistant to all antibiotics, and for some strains, multiple resistances were observed. Of E. faecium strains, 10.4% were positive for one or more virulence determinants, compared to 78.7% of E. faecalis strains. Strains exhibiting virulence traits were not necessarily positive for all traits; thus, the incidence of virulence factors may be considered to be strain specific.

scholarly journals Utility of Chromogenic Medium in Characterization of Enterococci in Urinary Tract Infection and Phenotypic Detection of Their Virulence Factors

2021 ◽  
Vol 11 (5) ◽  
pp. 278-283
Author(s):  
Betu Rama Soujanya ◽  
Banashankari G S
Keyword(s):  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Enterococcus Faecalis ◽  
Virulence Factors ◽  
Enterococcus Faecium ◽  
Antibiotic Sensitivity ◽  
Morbidity And Mortality ◽  
Enterococcus Species ◽  
Chromogenic Medium

Introduction: Enterococci from being intestinal commensals have evolved in becoming pathogens and are associated with significant morbidity and mortality Aims & Objectives: This study was done to speciate the uropathogenic Enterococci using the chromogenic medium and to determine the antibiogram also to detect virulence factors phenotypically. Materials and methods: The study included a total of 30 uropathogenic Enterococci isolated over 6 months. Speciation was done using HiCrome Enterococcus faecium agar base. Antibiotic sensitivity was done by the Kirby Bauer Disc Diffusion method as per Clinical and Laboratory Standards Institute (CLSI) guidelines. Among the virulence factors hemolysin, haemagglutination, and gelatin liquefaction tests were done. Results: Amongst the 30 enterococci isolates, 17 were Enterococcus faecalis (E. faecalis) (56.66%) & 13 were Enterococcus faecium (E. faecium) (43.33 %). 100% of the Enterococcus species were sensitive to Vancomycin & Teicoplanin. 66.67% of the Enterococci showed hemolysis, 10% haemagglutination, and 43.33% gelatinase property. Conclusion: Most common isolated species were Enterococcus faecalis. The changing patterns of antibiotic sensitivity to Enterococci in patients with urinary tract infection possess difficulty in selection of the antibiotics. Failure to synergistic therapy is seen in cases of resistance to High-level Gentamicin. Therefore, speciation and antibiotic sensitivity patterns will help in setting up an empirical therapy and thereby help in the reduction of morbidity and mortality. Key words: Antibiotic susceptibility, Chrome agar, Enterococcus species, virulence factors.

scholarly journals PREVALENCE OF VIRULENCE FACTORS AMONG CLINICAL ISOLATES OF ENTEROCOCCUS SPP.

2016 ◽  
Vol 9 (9) ◽  
pp. 72 ◽  
Author(s):  
Umadevi Sivaraman ◽  
Ravichandran L ◽  
Pramodhini S ◽  
Srirangaraj S ◽  
Seetha Ks
Keyword(s):  
Enterococcus Faecalis ◽  
Virulence Factors ◽  
Enterococcus Faecium ◽  
Sheep Blood Agar ◽  
Clinical Isolates ◽  
Blood Agar ◽  
Sheep Blood ◽  
Biofilm Production ◽  
Enterococcus Spp

ABSTRACTObjective: To identify some of the virulence factors such as hemolysin, gelatinase, and biofilm production among the clinical isolates of enterococci.Methods: Hemolysin detection using sheep blood agar. Gelatine agar was used for gelatinase production, and tube adherence method was used fordetecting biofilm production.Results: Hemolysin production observed in 49% of isolates, gelatinase production in 41% of isolates, and 46% of isolates were produced biofilm.Conclusion: Virulence factors production was noticed more in Enterococcus faecalis than Enterococcus faecium. It is necessary to find theproduction of important virulence factors among the clinical isolates as they are always associated with virulence of the organism including drugresistance.Keywords: Hemolysin, Gelatinase, Biofilm, Enterococcus.

scholarly journals Role of Methionine Sulfoxide Reductases A and B of Enterococcus faecalis in Oxidative Stress and Virulence

2010 ◽  
Vol 78 (9) ◽  
pp. 3889-3897 ◽  
Author(s):  
Chen Zhao ◽  
Axel Hartke ◽  
Marilena La Sorda ◽  
Brunella Posteraro ◽  
Jean-Marie Laplace ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Enterococcus Faecalis ◽  
Galleria Mellonella ◽  
Methionine Sulfoxide ◽  
Peritoneal Macrophages ◽  
Infection Model ◽  
Repair Enzymes ◽  
Methionine Sulfoxide Reductases ◽  
Mouse Peritoneal Macrophages

ABSTRACT Methionine sulfoxide reductases A and B are antioxidant repair enzymes that reduce the S- and R-diastereomers of methionine sulfoxides back to methionine, respectively. Enterococcus faecalis, an important nosocomial pathogen, has one msrA gene and one msrB gene situated in different parts of the chromosome. Promoters have been mapped and mutants have been constructed in two E. faecalis strains (strains JH2-2 and V583) and characterized. For both backgrounds, the mutants are more sensitive than the wild-type parents to exposure to H2O2, and in combination the mutations seem to be additive. The virulence of the mutants has been analyzed in four different models. Survival of the mutants inside mouse peritoneal macrophages stimulated with recombinant gamma interferon plus lipopolysaccharide but not in naïve phagocytes is significantly affected. The msrA mutant is attenuated in the Galleria mellonella insect model. Deficiency in either Msr enzyme reduced the level of virulence in a systemic and urinary tract infection model. Virulence was reconstituted in the complemented strains. The combined results show that Msr repair enzymes are important for the oxidative stress response, macrophage survival, and persistent infection with E. faecalis.

Sign in / Sign up

Export Citation Format

Share Document