A case of fatal respiratory diphtheria imported from Poland to Germany: possible link to an undetected imported diphtheria cluster in Poland?

Objective: Diphtheria is a re-emerging vaccine-preventable disease, mainly caused by toxigenic Corynebacterium diphtheriae.

Methods: Here, we report a fatal respiratory diphtheria infection in a Polish woman travelling to Germany possibly linked to a cutaneous diphtheria infection in a homeless man living in the same geographic area. Laboratory diagnostics involving MALDI-TOF MS, tox-gene PCR, Lateral Flow Immuno Assay, a modified Elek test and Next Generation Sequencing (NGS) identified the causative strain as cotrimoxazole-resistant toxigenic Corynebacterium diphtheriae biotype mitis, sequence type ST574. Moreover, a review on the diphtheria situation in Poland is presented.

Results: NGS data suggest a common source of infection in Poland and a possible link to the Europe-wide outbreak of imported diphtheria with C. diphtheriae since 2022. This is the first diphtheria case in Poland since 2000.