Colitis caused by multidrug-resistant Klebsiella Pneumoniae infection in 6 horses in SouthEast Germany: case series

Introduction: Clinical diseases affecting the respiratory and reproductive tract caused by the gram-negative bacterium Klebsiella pneumoniae have been reported in horses. Klebsiella pneumoniae can cause diarrhea in humans and other species such as dogs and cattle. Thus far, this facultative anaerobe has been isolated in the feces of healthy horses and in horses with diarrhea as a finding of coinfection with other colitis pathogens. This case series describes new information pertaining to Klebsiella pneumoniae as a sole pathogen in equine (entero-) colitis.

Clinical history: Retrospective case series of five horses and one foal hospitalized in 2022/2023.

Relevant clinical findings: All cases presented with typical clinical signs of (entero-) colitis of varying severity, to include dehydration, diarrhea, hypoproteinemia, and intestinal wall thickening.

Evidence-based diagnosis: A positive fecal bacterial culture for Klebsiella pneumoniae as the sole intestinal pathogen was obtained in all six cases, including one foal. Comprehensive testing for other viral, bacterial and parasitic pathogen co-infection was negative. All adult horses with colitis were confirmed with multidrug-resistant strains of Klebsiella pneumoniae.

Treatment and management: Cases received individualized supportive treatment for colitis. All patients were additionally treated with antimicrobials guided by available susceptibility testing for Klebsiella pneumoniae.

Evolution: Five out of six cases recovered. One horse was euthanized due to severity of disease; post mortem examination was not performed.

Discussion: This cases series newly highlights the importance of multidrug-resistant strains of Klebsiella pneumoniae as a sole pathogen in cases of equine intestinal disease, similar to which is observed in other species. The close proximity between humans and horses increases the risk for transmission of zoonotic diseases and requires that proper biosecurity and use of antimicrobial treatment is instituted.

References

1. Ribeiro M G, et al. Klebsiellainduced infections in domestic species: a caseseries study in 697 animals (1997–2019). Brazilian Journal of Microbiology; 2022. 53:455–464.
2. Loncaric I, et al. Broad-Spectrum Cephalosporin-Resistant Klebsiella spp. Isolated from Diseased Horses in Austria. Animals; 2020. 10, 332.
3. Estell K E, et al. Pneumonia Caused by Klebsiella spp. in 46 Horses. J Vet Intern Med; 2016. 30:314–321.
4. Özgür N Y, A. Bagcigil A F, Ikiz S. Isolation of Klebsiella pneumoniae from Mares with Metritis and Stallions, Detection of Biotypes and Capsule Types. Turk J Vet Anim Sci; 27; 2003. 241-247.
5. Valkova I, Barton A K, Briese B, Kershaw O, Gehlen H. Klebsiella pneumoniae causing colitis and terminal sepsis in a horse. Pferdeheilkunde – Equine Medicine 39; 2023. 325–331 p