Case Report: Toxigenic Corynebacterium ulcerans Diphtheria-Like Infection in a Horse in the United Kingdom

Abstract

Corynebacterium ulcerans (C. ulcerans) may cause diphtheria in humans and can be carried by a wide range of animal species including dairy cows and, more recently, dogs and cats that have been increasingly involved in zoonotic trasmission. We isolated and characterized, by WGS, a toxigenic C. ulcerans strain from a diseased horse in the United Kingdom showing clinical signs of respiratory diphtheria comparable to those seen in people. Our results indicate a role for horses as reservoirs for zoonotic C. ulcerans.

Pastern dermatitis outbreak associated with toxigenic and non‐toxigenic Corynebacterium diphtheriae and non‐toxigenic Corynebacterium ulcerans at a horse stable in Finland, 2021

“…The genome of C. ulcerans CP054583, an equine isolate published by Zendri et al. (2021), was included in the C. ulcerans minimum spanning tree. C. diphtheriae sequence types (ST) were determined using the Center for Genomic Epidemiology MLST 2.0 service (Larsen et al., 2012).…”

“…Pastern dermatitis specimens from the horses in this study were not investigated for parapoxvirus. from the USA (Henricson et al, 2000), the UK (Zendri et al, 2021), and Ireland (Leggett et al, 2010). Currently, human cases of diphtheria caused by C. ulcerans have outnumbered those caused by C. diphtheriae (Bonmarin et al, 2009;Wagner et al, 2010).…”

“…Other diphtheria‐like organisms identified in animals include biovar C. diphtheriae subsp. belfanti , C. ulcerans , C. rouxii , C. uterequi , and C. pseudotuberculosis (Baraúna et al., 2017; Corboz et al., 1996; Oliveira et al., 2014; Rückert et al., 2015; Schlez et al., 2021; Sing et al., 2016; Zendri et al., 2021). However, classic diphtheria is rare in animals.…”

“…Based on epidemiologic studies and sequence homology, zoonotic transmission of C. ulcerans ‐type diphtheria between pigs and humans (Berger et al., 2013; Schuhegger et al., 2009) and between wild animals, dogs, and humans (Katsukawa et al., 2016) seems likely. Sporadically, C. ulcerans findings among game, hunting and pet dogs, cats and horses have been reported (Abbott et al., 2020; Carfora et al., 2018; Eisenberg et al., 2014; Katsukawa et al., 2016; Museux et al., 2023; Saeki et al., 2015; Zendri et al., 2021). During 2002–2008 most of the human C. ulcerans cases in France had had animal contact (dogs or cats) before infection, but animal‐human transmission could not always be confirmed due to negative animal test results or lack of testing of animals (Bonmarin et al., 2009).…”

Corynebacterium of thediphtheriaecomplex in companion animals: clinical and microbiological characterization of 64 cases from France

“…Animals from which C. ulcerans is isolated can be asymptomatic carriers but can also present clinical symptoms, such as ulcerative dermatitis and chronic rhinitis (Lartigue et al, 2005; Carfora et al, 2018; Katsukawa et al, 2012; Abbott et al, 2020). Horses can also carry C. ulcerans and sometimes show signs of respiratory diphtheria (Zendri et al, 2021).…”