Unfortunately, approximately 15% of foster kittens will die before 8 weeks of age. The large majority of these kittens exhibit clinical signs of diarrhea or post mortem evidence of enteritis (intestinal inflammation). A specific cause of the enteritis is usually not determined and many kittens are frequently treated empirically with probiotics that contain enterococci. Gram-positive enterococci are considered part of the natural intestinal environment and an important part of the enteric microbiome. A probiotic commonly administered to kittens having diarrhea contains Enterococcus faecium. Yet, several other strains of E. faecium and E. faecalis are considered serious pathogens. This creates complicated and interconnected roles of the enterococcal community in health and disease. 
The authors determined a need to better understand this scenario and used the study to characterize the ileum mucosa-associated enterococcal community of 50 healthy and 50 terminally ill foster kittens. The purpose was to determine the prevalence, species diversity, virulence traits, clonality, and antibiotic resistance of this enterococcal community in the small intestines of very young kittens and their associations with disease mortality.
Findings suggest that E. hirae is the most common species of enterococcus found and will adhere more extensively to the small intestinal epithelium in apparently healthy kittens. In contrast, non-E. hirae enterococci, most notably E. faecalis, were more commonly isolated from the ileal mucosa of kittens with terminal illness. It was also determined that the E. faecalis isolates had more numerous virulence traits and multiple antimicrobial resistances (such as to tetracycline, erythromycin, chloramphenicol, linezolid, quinupristin-dalfopristin, and ciprofloxacin).
It is possible that the intestinal enterococci of sick kittens may act as a reservoir for potential transmission of antimicrobial resistance genes to the environment and/or to other hosts. In addition, the attachment of Escherichia coli to the intestinal epithelium was substantially associated with terminal illness and not found in any kitten with adherent E. hirae. The authors feel the findings identify a significant difference in the species of enterococci cultured from the ileal mucosa of kittens with terminal illness compared to the species cultured from healthy kittens. E.coli is identified as a potentially important intestinal pathogen in young kittens but the presence and adherence of E. hirae might competitively inhibit or deter the attachment of E. coli. [VT]
FUNDING: This project was partially funded by Winn Feline Foundation grants W09-022 and W11-013.
See also: Nicklas JL, Moisan P, Stone MR, et al. In situ molecular diagnosis and histopathological characterization of enteroadherent Enterococcus hirae infection in pre-weaning age kittens. J Clin Microbiol 2010;48:2814-2820.