Molecular Detection and Virulence Gene Profiling of Enterococcus spp. in Pediatric Diarrheal Cases

Abstract

Objective: Enterococcus spp. are recognized as significant opportunistic pathogens in the pediatric diarrheal process, with varied virulence attributes and growing antimicrobial resistance. The objective of this study is to detect the species of Enterococcus spp. recovered from children with diarrhea in Iraq and to determine the distribution of some important virulence genes (esp, cylA, efaA, asa1, and gelE).

Methods: Two hundred stool samples were obtained from patients with diarrhea; among these, twenty phenotypical and biochemical Enterococcus isolates were selected. The bacterial DNA was extracted, and the 16S rRNA gene and virulence genes were amplified by PCR. The 16S rRNA amplicons were sequenced and aligned, and a phylogenetic tree was generated by MEGA11. The distribution of genes was evaluated by a Chi-square test.

Results: Phylogenetic analysis classified the isolates into two clades: 14 E. faecalis and 6 E. faecium strains, which were closely related to strains found in other countries. The detection rates by PCR for cylA and gelE (85%) were higher than those for esp (80%), efaA (75%), and asa1 (65%). Gene frequencies also did not differ significantly  (χ² = 3.13, P = 0.537).

Conclusion: The Enterococcus isolates studied had several different virulence genes with cytolytic and biofilm-forming properties as the most abundant character. Species-level classification of the strains, as well as virulence profiling, was successfully achieved using the 16S rRNA gene and gene profiling. Genetic homology with other global strains implies widespread conservation and virulence traits.