E. faecalis microorganism may play important role in contributing to decreased egg hatchability.
November 5, 2024
The U.S. Poultry & Egg Association (USPOULTRY) and the USPOULTRY Foundation announced the completion of a funded research project that identified virulent from avirulent strains of Enterococcus faecalis isolates. The project is part of the association’s comprehensive research program encompassing all phases of poultry and egg production and processing.
Project #F112: “Identifying Virulent Avian Enterococcus faecalis Isolates by Using Matrix-Assisted Laser Desorption/Ionization – Time of Flight Mass Spectroscopy” (MALDI-TOF MS) was by conducted by researchers at the University of Nebraska-Lincoln and led by principal investigator Dr. Donald L. Reynolds with the Nebraska Veterinary Diagnostic Center.
E. faecalis, a ubiquitous microorganism that is frequently found in hatcheries and unhatched eggs and is egg transmitted, may play an important role in contributing to decreased hatchability.
The current method to assess its virulence is to grow the organism, inoculate chicken embryos and determine if the E. faecalis strain used as the inoculum kills the embryo, according to the research summary. Based on the embryo lethality assay (ELA), researchers have found that some E. faecalis strains are virulent in that they cause embryo mortality and prevent fertile eggs from developing. However, other strains have been found to be avirulent and seem to have minimal effects on embryos.
The goal of this project by Reynolds and colleagues was to develop a diagnostic tool that distinguishes virulent from avirulent strains of E. faecalis in a rapid and cost-effective manner by using MALDI-TOF MS. The two specific objectives were:
Use an ELA to identify at least 25 virulent and 25 avirulent strains of E. faecalis, which would then be used to develop the MALDI-TOF MS methodology.
Develop a biomarker model using MALDI-TOF MS spectra capable of accurately differentiating virulent from avirulent strains of E. faecalis.
The researchers evaluated isolates from a variety of sources, including broiler chickens, laying chickens, turkeys and game birds (ring-neck pheasants).
The MALDI-TOF MS method they developed was able to distinguish between very low avirulent E. faecalis isolates and highly virulent E. faecalis isolates. However, the method was not able to clearly categorize E. faecalis isolates found to be of low and moderate virulence (i.e., in-between highly virulent and avirulent) into avirulent or virulent categories.
Data from this project was used in another study to determine that the virulence factor that kills the embryo is a bacterial exotoxin produced by E. faecalis isolates – an important finding in understanding the pathogenesis of E. faecalis infections, according to the summary. Investigators are now using the MALDI-TOF MS method developed in Project #F112 in hopes of demonstrating the exotoxin, which should prove a useful tool for diagnosing and for conducting further research on E. faecalis infections.
The research summary of the completed project is available on the USPOULTRY website, and information on other association research may also be found by visiting www.uspoultry.org.
USPOULTRY, founded in 1947 and based in Tucker, Ga., serves its poultry and egg members through research, education, communications and technical services. The USPOULTRY Foundation's mission is to support the recruitment and training of the brightest students, seek and fund scientific research, foster student scientists and promote careers in the poultry and egg industry.
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