Retinopathy associated with enterococcus enteropathy in the neonatal rat

Area of Science:

• Neonatal ophthalmology
• Gastroenterology
• Microbiology

Background:

• Preretinal neovascularization, analogous to retinopathy of prematurity (ROP), has been observed in neonatal rats with diarrhea.
• A novel enterococcus species, Enterococcus rattus, was isolated from the duodenum of these rats.

Purpose of the Study:

• To investigate the effect of enteropathy induced by Enterococcus rattus on retinal vasculature in neonatal rats.
• To further understand the potential link between enterococcal infection and ROP-like conditions.

Main Methods:

• 150 newborn Sprague-Dawley rats were divided into two groups: inoculated with E. rattus (n=100) and control (n=50).
• Animals were gavaged on day 2, raised in room air, and assessed on day 13.
• Retinal vasculature was evaluated using fluorescent microscopy and ADPase staining; duodenal and blood samples were cultured.

Main Results:

• 100% of inoculated rats developed diarrhea and tested positive for E. rattus.
• 55% of inoculated rats showed preretinal neovascularization, compared to 2% in controls (P=0.001).
• Inoculated rats exhibited reduced retinal vascular areas, severe growth retardation, and acidosis.

Conclusions:

• A novel enterococcal enteropathy is associated with preretinal neovascularization in neonatal rats, mimicking ROP.
• These findings suggest that factors other than inspired oxygen play a role in ROP development.