Characterization of Enterococcus faecalis isolates by chicken embryo lethality assay and ERIC-PCR

Abstract

Enterococcus faecalis is the major causative agent of amyloid arthropathy in chickens. Given the difficulty of estimating the risk from field strains, the embryo lethality assay (ELA) is proposed in this study as a model to predict the virulence of 68 avian E. faecalis strains. Additionally, Enterobacterial Repetitive Intergenic Consensus Polymerase Chain Reaction (ERIC-PCR) was used to characterize the genetic diversity of the E. faecalis strains. The ELA was performed 10 times with subsets of 7-8 E. faecalis strains each on a sample of 9987 eggs, including control groups. An estimated 3-24 colony-forming units were inoculated into the allantoic cavity of 10-day-old embryos. The embryonic mortality rate (EMR) was determined by means of candling the eggs over a period of seven days. The ELA was able to distinguish the virulence of the E. faecalis strains. Twenty-six strains were considered as avirulent strains with an EMR of below 40%. Five strains were highly virulent with an EMR above 80%. The remaining 37 strains were classified as strains of moderate virulence, causing an EMR between 40% and 80%. The highest EMR occurred three and four days post-inoculation (p.i.). From the fourth day p.i., almost no embryonic mortality was observed. Therefore, the ELA could be optimized by reducing experiment duration to four days p.i. ERIC-PCR did not cluster the strains according to its virulence, although ERIC banding patterns revealed a considerable genetic diversity. In conclusion, the ELA can be considered a reliable and useful tool to predict the virulence of avian E. faecalis strains.

Study Genetic Relationship among Enterococcus Faecalis Strains Collected from Urine Harbored Different Virulence Profiles Using Eric-pcr Assay

“…This may due to high relationship among these isolates in addition to the high virulence content for most isolates, only one isolate expressed single studied virulence gene, while most isolates have considerable content of virulence ability as shown in Table (1). This finding may agree to study by Blanco et al, 2018 who found ERIC-PCR didn't cluster stains according their virulence. Besides, Eaton &Gasson, 2001 andBorst et al, 2014 suggested that the molecular taxonomy of Enterococcus spp.…”

Molecular Typing Reveals Environmental Dispersion of Antibiotic-Resistant Enterococci under Anthropogenic Pressure

“…DNA fingerprinting by ERIC-PCR is widely applicable since ERIC primers do not exclusively target enterobacterial repetitive elements [ 45 ]. It was demonstrated that it is a reliable tool, with high discriminatory power among Enterococcus strains isolated from food [ 46 , 47 , 48 ], water samples [ 49 ], clinical specimens obtained from animals [ 50 , 51 ] and humans [ 52 ]. In previous studies, the genotyping assay directed ERIC1 or ERIC1 in combination with ERIC2 primers against E. faecalis and/or E. faecium genomes.…”

Genetic Diversity of Vancomycin Resistance Enterococcus Spp. Isolated from Animal, Human and Environmental Origin

“…VRE isolates from different sources were fingerprinted using ERIC-PCR assay as described by Blanco., et al [10] modifications in order to obtain a better band pattern. ERIC-1…”

“…Reliable molecular typing methods for purpose of finding the relatedness between bacterial isolates have become progressively important to evaluate outbreak and endemic conditions with food borne pathogens. Different techniques like Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR [10], Repetitive Extergenic Palindromic (REP) PCR [11], PFGE-Pulsed-field gel electrophoresis [12,13], determination of 16S rRNA sequences [14,15], RFLP-Restriction Fragment Length Polymorphism [16], MLST-Multilocus Sequence Typing [17][18][19][20] and AFLP-Amplified Fragment Length polymorphisms [21,22] are generally used for typing of Enterococcus spp. PCR-based techniques like REP and ERIC PCR are accurate, rapid, reproducible, sensitive, specific and reliable diagnostics, which are used for determining different DNA fingerprints [23].…”