Anja Berger (Oberschleißheim / DE), Alexandra Dangel (Oberschleißheim / DE), Katja Bengs (Oberschleißheim / DE), Vyacheslav Melnikov (Oberschleißheim / DE), Manuel Ranzinger (Waldkirchen / DE), Sonja Kandlbinder (Waldkirchen / DE), Stefan Pfeiffer (Waldkirchen / DE), Frank Wiedemann (Passau / DE), Elisabeth Spindler (Freyung / DE), Desiree Haug (Freyung / DE), Stefanie Böhm (Oberschleißheim / DE), Andreas Sing (Oberschleißheim / DE)
Objectives
Diphtheria is still rarely observed in industrialized countries, but we observe an increase of zoonotic Corynebacterium (C.) ulcerans infections in humans. C. ulcerans may (similarly to C. diphtheriae) harbour lysogenic beta-corynephages bearing the tox gene encoding diphtheria toxin (DT). Toxigenic C. ulcerans may cause classical respiratory diphtheria or diphtheria-like syndromes as well as cutaneous diphtheria. Companion cats and dogs, other domestic and wild animals, serve as a reservoir and a source of zoonotic C. ulcerans infection. We report on a patient with chronic skin ulcerations due to circulatory disorders, complicated by wound diphtheria. The patient´s asymptomatic three cats were examined in order to find the potential source of infection.
Materials & Methods
Strain identification was performed by biochemical differentiation and MALDI-TOF analysis (MALDI Biotyper; Bruker Daltonics, Germany). Susceptibility testing was performed according to EUCAST guidelines. Toxigenicity was verified by real-time PCR, the optimized modified Elek-test and a recently published Lateral Flow Immunoassay providing a more rapid detection of diphtheria toxin producing strains. Whole generation sequencing (WGS) was carried out on Illumina systems and data analysis by core genome Multi Locus Sequencing (cgMLST).
Results
A toxigenic C. ulcerans strain was cultivated in the patient´s wound swab in a mixed culture together with Enterobacter cloacae and Klebsiella oxytoca. Pharyngeal carriage of a toxigenic C. ulcerans strain occured in one of the three investigated asymptomatic cats. Analysis of WGS, epidemiological and clinical data indicate strain transmission of the toxigenic C. ulcerans from the pet cat to its owner via direct contact.
Discussion
Since 15 years zoonotic tox+ C. ulcerans has outnumbered the "classical" pathogen C. diphtheriae related cases in Germany – with the exception of the ongoing European 2022 diphtheria outbreak among refugees.Our experience responding to a zoonotic incident caused by C. ulcerans has highlighted the need for more robust surveillance and understanding of this emerging pathogen in both animals and humans.