Disease relevance of EF0700

• An HlyB-type function is required for expression of the Enterococcus faecalis hemolysin/bacteriocin [1].
• Hemolysin of Streptococcus faecalis subspecies zymogenes contributes to virulence in mice [2].
• Hemolysin was more common in nonendocarditis clinical isolates and in hospital fecal isolates (37% and 31%, respectively) than among endocarditis and community fecal isolates (16% and 20%, respectively) [3].
• In this study, isogenic E. faecalis strains were compared to determine whether the presence of the hemolysin-encoding plasmid affected the severity of disease in a rabbit endophthalmitis model [4].
• The inferred protein, CylB, was observed to be independently expressed in E. coli and capable of complementing an insertion mutation in the cloned hemolysin/bacteriocin operon in trans [1].

High impact information on EF0700

• This study reviewed the incidence of virulence factors such as hemolysin, gelatinase, aggregation substances (asa1 and asa373), or the enterococcal surface protein (Esp) in isolates from liver transplant patients [5].
• In conclusion, this model allows attenuated mutants to be detected, corroborates prior reports that hemolysin is a virulence factor, and suggests a role for gelatinase in virulence of E. faecalis in mice; the attenuated purine auxotroph may provide a system for developing vectors for in vivo expression systems [6].
• Hemolysin production caused a 35-fold lower LD50 and a much shorter survival, similar to previous results using a peritonitis model without SRFE [6].
• Incidence of hemolysin, gelatinase, and aggregation substance among enterococci isolated from patients with endocarditis and other infections and from feces of hospitalized and community-based persons [3].
• Similar kinetics of killing were observed for derivatives of Enterococcus faecalis strains regardless of resistance to antimicrobial agents or production of beta-lactamase, hemolysin, gelatinase, or surface proteins involved in the aggregative response to pheromones [7].

Chemical compound and disease context of EF0700

• High incidence of hemolysin production by Enterococcus (Streptococcus) faecalis strains associated with human parenteral infections [8].
• The Streptococcus faecalis sex pheromone cAD1, which is involved in the conjugative transfer of the hemolysin plasmid pAD1, has been isolated and its structure determined [9].
• Streptococcus faecalis strain DS16 harbors two plasmids, a conjugative plasmid, pAD1, which encodes hemolysin and bacteriocin activities, and a nonconjugative plasmid, pAD2, encoding resistance to streptomycin, kanamycin, and erythromycin, the latter of which is inducible [10].
• The determinant for the peptide sex pheromone inhibitor iAD1 (iad) on the hemolysin/bacteriocin plasmid pAD1 of Enterococcus faecalis was sequenced [11].

Biological context of EF0700

• The E. faecalis hemolysin is encoded by large transmissible plasmids [4].
• Plasmid-associated hemolysin and aggregation substance production contribute to virulence in experimental enterococcal endocarditis [12].
• Strains exhibiting the normal hemolysin phenotype were significantly more virulent than the nonhemolytic insertion mutants [2].
• This fragment was associated with expression of hemolysin/bacteriocin component L and contained a 2,142-bp open reading frame [1].
• The nucleotide sequence of a 3,422-bp internal restriction fragment from the Enterococcus faecalis pAD1 hemolysin/bacteriocin-encoding region was determined [1].

Anatomical context of EF0700

• The hemolysin/bacteriocin produced by some strains of Enterococcus faecalis is active in the lysis of human, rabbit, and horse erythrocytes, but not those from sheep [13].
• The induction of superoxide anion generation by neutrophils was demonstrated to be directly proportional to the presence of the hemolysin/bacteriocin plasmid and was transferable to a non-hemolysin-producing laboratory strain by transconjugation [14].

Associations of EF0700 with chemical compounds

• The tetracycline resistance element was able to transpose to several sites on the S. faecalis hemolysin plasmid pAD1 and in each case resulted in a 15-kilobase insert [15].
• In contrast to the high frequency of hemolysin producers among parenteral isolates, strains derived from fecal specimens of healthy individuals exhibited a low (17%) incidence of hemolysin production [8].
• Multidrug resistance, glycopeptide resistance, presence of asa1, and production of hemolysin appeared to be statistically significant features related to epidemicity [16].
• Phosphatidylcholine is probably the binding component on the membrane of erythrocytes for E. faecalis hemolysin [17].

Other interactions of EF0700

• A 64-kb genetic element harboring a vanB vancomycin-resistance (VmR) gene cluster was shown to translocate from the chromosome of Enterococcus faecalis BM4281 into the hemolysin (Hly) plasmid, pIP964 [18].

Analytical, diagnostic and therapeutic context of EF0700

• Experimental infections (n = 6) with 10(1)-10(4) E. faecalis organisms harboring the hemolysin-encoding plasmid resulted in a 98% loss of retinal function (by electroretinography [ERG]) and white reflex by postoperative day 3 [4].
• Results of light microscopy, slit-lamp examination, ERG, and indirect ophthalmoscopy indicated that infections with hemolysin-encoding plasmid-containing E. faecalis resulted in a more aggressive endophthalmitis compared with the endophthalmitis caused by plasmid-free E. faecalis [4].
• Recent human epidemiologic studies and animal research suggest that this hemolysin/bacteriocin may enhance the pathogenicity of hemolysin-producing enterococci compared with non-hemolysin-producing strains [14].
• Gelatinase- and hemolysin-producing strains of Enterococcus faecalis have been shown to be virulent in animal models of enterococcal infections [19].
• Plasmids harboured in donor and transconjugant strains, responsable for antibiotic-resistance, for hemolysin and gelatinase activity, were analyzed later by agarose gel electrophoresis [20].

References