Improved detection of esp, hyl, asa1, gelE, cylA virulence genes among clinical isolates of Enterococci

Abstract

Objective: Virulence factors (VFs) among the clinical strains of enterococci play a vital role in pathogenesis. This study was aimed to screen for cylA, asa1, gelE, esp and hyl among Enterococcus faecalis (n = 89) and E. faecium (n = 51) by multiplex PCR. The previously reported multiplex PCR was modified to 2 duplex (asa1 and gelE, cylA and esp) PCRs and 1 simplex (hyl) PCR. The idea of the modification of the multiplex PCR proposed here emerged in the course of the research study when majority of the isolates which phenotypically exhibited virulence traits were found to be negative for the respective gene. Results: cylA, gelE and asa1 were significantly predominant in E. faecalis (59.55%, 85.39%, 86.51%) than E. faecium (1.96%, 60.78%, 9.80%) (p < 0.0001, p = 0.001967, p < 0.0001). hyl was detected in E. faecium (5.9%) only. The number of VFs detected in each isolate was recorded as the VF score. E. faecalis isolates had a VF score pattern of score 4 (34.83%), score 3 (26.96%), score 2 (28.08%) and score 1 (8.98%) while E. faecium had score 4 (1.96%), score 3 (7.84%), score 2 (25.49%) and score 1 (41.18%). This modification of the PCR protocol could resolve the problem of decreased detection of virulence determinants in enterococci.

Occurrence of multidrug‐resistantEnterococcus faeciumisolated from environmental samples

“…Enterococcus faecium isolates can act as opportunistic pathogens through the presence of different virulence factors, which may be associated with the ability of the cells to adhere to the host or to invade the tissues (Ferguson et al 2016;Bin-Asif and Abid-Ali 2019). The esp and gelE genes, which encode the surface protein Esp and gelatinase, respectively, have been described in clinical E. faecium isolates and may be associated with biofilm formation (Daniel et al 2017;Kiruthiga et al 2020). Besides, the esp and gelE genes have been reported in VRE and vancomycin-susceptible E. faecium isolates, as showed in this study (Comerlato et al 2013).…”

Phenotype–Genotype Correlations and Distribution of Key Virulence Factors in Enterococcus faecalis Isolated from Patients with Urinary Tract Infections

“…Absence of blood hemolysis despite the presence of cyl was reported in other studies. 48,49 Cytolysin expression was also found to be associated with increasing severity of infection. 50 Of note, previous studies 18,33,51 have analyzed virulence factor correlations in enterococci, in particular E. faecalis, isolated from Egyptian patients; however, the specificity of this work is that it solely focuses on E. faecalis samples from UTIs and that it calculates statistical associations between virulence genotypes and phenotypes, with particular emphasis on biofilm formation and adherence, in this type of clinically important infections.…”

Molecular Characterization of Enterococcus Isolates From Different Sources in Estonia Reveals Potential Transmission of Resistance Genes Among Different Reservoirs

“…We searched the genomes of our isolates for the presence of the E. faecalis and E. faecium virulence factors associated in the literature with human infections. The E. faecalis -specific virulence genes included in our search were ace , asa1 , cylA , efaA fs , espfs , gelE , hyl A , and hylB ( Singh et al, 1998 , 2010 ; Vankerckhoven et al, 2004 ; Stępień-Pyśniak et al, 2019 ; Kiruthiga et al, 2020 ), and the E. faecium -specific virulence factors included in our search were acm , efaA fm , ecbA , espfm , hylEfm , ptsD , scm , sgrA , orf1481 , and IS 16 and four hospital variants of complete pili gene clusters ( Freitas et al, 2018 ; Stępień-Pyśniak et al, 2019 ). The search was conducted by the alignment of the gene sequences against the genome assemblies using BLASTn ( Altschul et al, 1997 ), with an identity threshold of 95% and gene coverage threshold per hit of 80% (for a more detailed description of the searched virulence genes, see Supplementary Table S3 ).…”