Researchers from the Institut Pasteur in Paris, in collaboration with the European Diphtheria Consortium, evaluated 363 cases of toxin-producing C. diphtheriae infections reported in 10 European countries in 2022 (Hoefer A, et al. Corynebacterium diphtheriae outbreak in migrant populations in Europe. N Engl J Med. 2025 Jun 19;392(23):2334-2345). They found that 269 of the cases (77%) had cutaneous diphtheria, 53 (15%) had respiratory diphtheria, and 9 (2.3%) had both respiratory and cutaneous symptoms. The authors also performed whole-gene sequencing and antimicrobial susceptibility testing of the isolates. They found that isolates carrying the ermX gene were resistant to erythromycin, and those carrying the pbp2m gene were resistant to penicillin but susceptible to amoxicillin.
The authors concluded, “The distribution of each genetic cluster of C. diphtheriae isolates across multiple countries in Europe showed repeated cross-border spread. The large number of C. diphtheriae infections among migrants is a cause for concern, particularly given that antimicrobial-resistance phenotypes threaten the efficacy of first-line treatments.”
Given that international travel is common, and that antimicrobial resistance patterns are worrisome, this study again emphasizes the importance of vaccination.
Researchers from the Institut Pasteur in Paris, in collaboration with the European Diphtheria Consortium, evaluated 363 cases of toxin-producing C. diphtheriae infections reported in 10 European countries in 2022 (Hoefer A, et al. Corynebacterium diphtheriae outbreak in migrant populations in Europe. N Engl J Med. 2025 Jun 19;392(23):2334-2345). They found that 269 of the cases (77%) had cutaneous diphtheria, 53 (15%) had respiratory diphtheria, and 9 (2.3%) had both respiratory and cutaneous symptoms. The authors also performed whole-gene sequencing and antimicrobial susceptibility testing of the isolates. They found that isolates carrying the ermX gene were resistant to erythromycin, and those carrying the pbp2m gene were resistant to penicillin but susceptible to amoxicillin.
The authors concluded, “The distribution of each genetic cluster of C. diphtheriae isolates across multiple countries in Europe showed repeated cross-border spread. The large number of C. diphtheriae infections among migrants is a cause for concern, particularly given that antimicrobial-resistance phenotypes threaten the efficacy of first-line treatments.”
Given that international travel is common, and that antimicrobial resistance patterns are worrisome, this study again emphasizes the importance of vaccination.