Corynebacterium rouxii, a recently described member of the C. diphtheriae group isolated from three dogs with ulcerative skin lesions

Abstract

Corynebacterium (C.) diphtheriae is one of the two etiological pathogens for human diphtheria with significant morbidity and mortality. Recently, members of its biovar Belfanti have been described as two novel species, C. belfantii and C. rouxii. The most important virulence factor and also the premise to cause diphtheria is the isolate’s capacity to encode and express the diphtheria toxin (DT). In contrast to C. ulcerans, which represents a potentially zoonotic pathogen, C. diphtheriae (incl. the novel deduced species) has almost exclusively been found to comprise a human pathogen. We here report three rare cases of C. rouxii isolation from dogs suffering from disseminated poly-bacterial exsudative to purulent dermatitis and a traumatic labial defect, respectively. The isolates were identified as C. diphtheriae based on commercial biochemistry and matrix-assisted laser desorption/ionisation–time of flight mass spectrometry (MALDI-TOF MS) analysis. However, recently described specific spectral peaks were highly similar to spectra of C. rouxii, which was confirmed by whole genome sequencing. Further investigations of the dog isolates for the presence of DT by tox gene qPCR revealed negative results. The findings from this study point out that skin infections in companion animals can be colonized by uncommon and so believed human specific pathogens, thereby resembling the clinical signs of cutaneous diphtheria.

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

“…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.…”

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

“…Similarly, C. rouxii may also be zoonotic: no interhuman transmission has been reported yet, and in addition to human cases, it has been so far identified in dogs, cats and a fox (Badell et al, 2020;Hall et al, 2010;Schlez et al, 2021;Sing et al, 2016). To our knowledge, strains of C. belfantii were only isolated from human respiratory samples.…”

Proteomics of Toxigenic Corynebacteria

“…Recently, a number of former C. diphtheriae strains of biovar Belfanti were taxonomically newly described as separate species, Corynebacterium belfantii [ 30 ] and Corynebacterium rouxii [ 31 , 32 ]. While partially included in the former in silico studies of C. diphtheriae mentioned above, no separate proteome studies were carried out for these new species to date, while limited information is available for mass spectrometry-based identification, as described below.…”