Outer membrane vesicles (OMVs) are released from the outer membrane of Gram-negative bacteria. Moreover, Gram-positive bacteria also produce membrane-derived vesicles. As OMVs transport several bacterial components, especially from the cell envelope, their interaction with the host cell, with other bacteria or as immunogens, have been studied intensely. Several functions have been ascribed to OMVs, especially those related to the transport of virulence factors, antigenic protein composition, and development as acellular vaccines. In this work, we review some of the recent findings about OMVs produced by specific pathogenic bacterial species.
These results suggest that PJ protects against the effects of a high-fat diet in body weight, and cholesterol levels.
Biofilm formation on medical and surgical devices is a major virulence determinant for Staphylococcus epidermidis. The bacterium S. epidermidis is able to produce biofilms on biotic and abiotic surfaces and is the cause of ocular infection (OI). Recent studies have shown that D-amino acids inhibit and disrupt biofilm formation in the prototype strains Bacillus subtilis NCBI3610 and Staphylococcus aureus SCO1. The effect of D-amino acids on S. epidermidis biofilm formation has yet to be tested for clinical or commensal isolates. S. epidermidis strains isolated from healthy skin (n53), conjunctiva (n59) and OI (n519) were treated with D-Leu, D-Tyr, D-Pro, D-Phe, D-Met or D-Ala and tested for biofilm formation. The presence of D-amino acids during biofilm formation resulted in a variety of patterns. Some strains were sensitive to all amino acids tested, while others were sensitive to one or more, and one strain was resistant to all of them when added individually; in this way D-Met inhibited most of the strains (26/31), followed by D-Phe (21/31). Additionally, the use of D-Met inhibited biofilm formation on a contact lens. The use of L-isomers caused no defect in biofilm formation in all strains tested. In contrast, when biofilms were already formed D-Met, D-Phe and D-Pro were able to disrupt it. In summary, here we demonstrated the inhibitory effect of D-amino acids on biofilm formation in S. epidermidis. Moreover, we showed, for the first time, that S. epidermidis clinical strains have a different sensitivity to these compounds during biofilm formation.
Staphylococcus epidermidis is a common commensal of healthy conjunctiva and it can cause endophthalmitis, however its presence in conjunctivitis, keratitis and blepharitis is unknown. Molecular genotyping of S. epidermidis from healthy conjunctiva could provide information about the origin of the strains that infect the eye. In this paper two collections of S. epidermidis were used: one from ocular infection (n = 62), and another from healthy conjunctiva (n = 45). All isolates were genotyped by pulsed field gel electrophoresis (PFGE), multilocus sequence typing (MLST), staphylococcal cassette chromosome mec (SCCmec), detection of the genes icaA, icaD, IS256 and polymorphism type of agr locus. The phenotypic data included biofilm production and antibiotic resistance. The results displayed 61 PFGE types from 107 isolates and they were highly discriminatory. MLST analysis generated a total of 25 STs, of which 11 STs were distributed among the ocular infection isolates and lineage ST2 was the most frequent (48.4%), while 14 STs were present in the healthy conjunctiva isolates and lineage ST5 was the most abundant (24.4%). By means of a principal coordinates analysis (PCoA) and a discriminant analysis (DA) it was found that ocular infection isolates had as discriminant markers agr III or agr II, SCCmec V or SCCmec I, mecA gene, resistance to tobramycin, positive biofilm, and IS256+. In contrast to the healthy conjunctiva isolates, the discriminating markers were agr I, and resistance to chloramphenicol, ciprofloxacin, gatifloxacin and oxacillin. The discriminant biomarkers of ocular infection were examined in healthy conjunctiva isolates, and it was found that 3 healthy conjunctiva isolates [two with ST2 and another with ST9] (3/45, 6.66%) had similar genotypic and phenotypic characteristics to ocular infection isolates, therefore a small population from healthy conjunctiva could cause an ocular infection. These data suggest that the healthy conjunctiva isolates do not, in almost all cases, infect the eye due to their large genotypic and phenotypic difference with the ocular infection isolates.
Staphylococci produce a large number of extracellular proteases, some of which are considered as potential virulence factors. Staphylococcus epidermidis is a causative agent of nosocomial infections in medical devices by the formation of biofilms. It has been proposed that proteases contribute to the different stages of biofilm formation. S. epidermidis secretes a small number of extracellular proteases, such as serine protease Esp, cysteine protease EcpA, and metalloprotease SepA that have a relatively low substrate specificity. Recent findings indicate a significant contribution of extracellular proteases in biofilm formation through the proteolytic inactivation of adhesion molecules. The objective of this work is to provide an overview of the current knowledge of S. epidermidis' extracellular proteases during pathogenicity, especially in the different stages of biofilm formation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.