Review of Virulence Factors of Enterococcus: An Emerging Nosocomial Pathogen

Abstract

not only in the treatment of enterococcal infections but also because the organism can horizontally transfer this resistant determinant to other Vancomycin-susceptible species. [6] Until recent times, the VRE strains were found sensitive to Linezolid. Resistance to Linezolid is slowly developing, posing several questions on the virulence factors and their survival mechanisms. [7] This review article focuses on the development of virulence factors of the organism and their signiÞ cance in survival of the organism. Genome of EnterococciThe two commonly isolated species of Enterococci associated with nosocomial infections are E. faecalis and E. faecium. The sequencing of the E. faecalis and E. faecium genomes [8] has been done by the Institute for Genomic Research [TIGR] and Joint Genomic Institute of the Dept of Energy in USA respectively. The genome of E. faecalis V583 and E. faecium ATCC BAA-472 has been sequenced. E. faecalis strain V583 is the Þ rst VRE exhibiting Van B phenotype. Some unique features of the genome are that over 25% of genome is made up of mobile and/or exogenously acquired DNA which includes a number of conjugative and composite transposons, a pathogenicity island, integrated plasmid genes phage regions, and high number of insertion sequence [IS]. A comprehensive genome-wide analysis identiÞ ed 134 putative surface exposed proteins that might be associated with colonisation or virulence.The genome of E. faecium is estimated to be around 2.9 Mb, slightly smaller than 3.2 Mb of E. faecalis strain V583. It consists of 2,928,706 base pairs in 300 contigs, 20 reads IntroductionEnterococci have attracted much attention in recent times due to their increased recognition as a cause of nosocomial 'super infection' in patients receiving antimicrobial agents.[1] They are intrinsically resistant / tolerant to many antibiotics and are able to acquire drug resistance either by chromosome, transfer of plasmid or transposon acquisition containing genetic sequences that confer resistance in other bacteria. [2] Until recently these ordinary bowel commensals languished as misclassiÞ ed streptococci and were commonly perceived 'as organisms which did not cause major or serious infection'.[3] The medical importance of Enterococci far outweighs the relatively insigniÞ cant proportion of the total adult human commensal they represent.[4] It is ranked as one of the leading organisms causing hospital-borne infection. In USA alone, eight lakh cases of enterococcal infections occur each year. AbstractEnterococcus, considered a normal commensal of intestinal tract, is fast emerging as a pathogen causing serious and life threatening hospital borne infections. This is attributed to acquisition of multi drug resistance and virulence factors of the organisms. The sequencing of Enterococcus faecalis has given a lot of insight into its genetic makeup. The E. faecalis strain V583, which has been sequenced, contains a total of 3182 open reading frames (ORFs) with 1760 of these showing similarity to known proteins and 221 of u...

A study on virulence factors and antimicrobial resistance pattern among enterococci isolated from various clinical specimens from a tertiary care hospital

“…10 Our prospective study was carried out on 100 Enterococcal isolates, during a 20 months period from May 2015 to December 2016at Aarupadai Veedu medical college and hospital. The predominant species isolated in this study were E.faecalis constituting 81% of isolates followed by 19% of E. faecium.…”

Detection of glycopeptide resistance genes in enterococci by multiplex PCR

“…1,2 Enterococci are important because of their role as the leading cause of nosocomial infections which have a significant role in dissemination and persistence of drug resistance genes. 3 Vancomycin is a member of a class of antibiotics referred to as glycopeptides therefore vancomycin resistant enterococci (VRE) can also be referred to as Glycopeptide resistant enterococci (GRE).…”

Prevalence of Virulence Factors Among Clinical Isolates of Enterococcus Spp.

“…In our study, 39 (43.8%) isolates of E. faecalis and 2 (18.18%) isolates of E. faecium were producing gelatinase. A study from India by Upadhyaya et al, in the year 2009, reported that 39% clinical isolates were producing gelatinase [10]. Another study by Strzelecki et al from Poland reported that, of 153 E. faecalis, 53% of strains producing gelatinase, and among these, isolates from CSF were commonly producing gelatinase (75%) followed by isolates from urine (71%) less frequently by isolates from wound and blood.…”

“…In our study, 42 (47.19%) isolates of E. faecalis and 4 (36.36%) isolates of E. faecium were producing biofilm, respectively. Upadhyaya et al from India reported that 32% of clinical isolates were producing biofilm, but only 16% of commensal isolates were producing biofilm [10]. The worldwide biofilm producing prevalence was varied from each other country.…”

“…The enterococci have been associated with biofilm in endocarditis, root canal infection, and ocular infection and urinary tract infection and in a variety of device-related infection in which biofilm was found on intrauterine devices, prosthetic heart valves, artificial hip prostheses catheters, and stents [9]. Biofilm production is nosocomial strains of organisms is an important pathogenic factor in causing infection in the hospital environment [10].…”