Abstract
In 2015, a cluster of respiratory diphtheria cases was reported from KwaZulu-Natal Province in South Africa. By using whole-genome analysis, we characterized 21 Corynebacterium diphtheriae isolates collected from 20 patients and contacts during the outbreak (1 patient was infected with 2 variants of C. diphtheriae). In addition, we included 1 cutaneous isolate, 2 endocarditis isolates, and 2 archived clinical isolates (ca. 1980) for comparison. Two novel lineages were identified, namely, toxigenic sequence type (ST) ST-378 (n = 17) and nontoxigenic ST-395 (n = 3). One archived isolate and the cutaneous isolate were ST-395, suggesting ongoing circulation of this lineage for >30 years. The absence of preexisting molecular sequence data limits drawing conclusions pertaining to the origin of these strains; however, these findings provide baseline genotypic data for future cases and outbreaks. Neither ST has been reported in any other country; this ST appears to be endemic only in South Africa.
Highlights
Mignon du Plessis, Nicole Wolter, Mushal Allam, Linda de Gouveia, Fahima Moosa, Genevie Ntshoe, Lucille Blumberg, Cheryl Cohen, Marshagne Smith, Portia Mutevedzi, Juno Thomas, Valentino Horne, Prashini Moodley, Moherndran Archary, Yesholata Mahabeer, Saajida Mahomed, Warren Kuhn, Koleka Mlisana, Kerrigan McCarthy, Anne von Gottberg
We included 2 archived clinical isolates of C. diphtheriae that were isolated in South Africa during the 1980s and 2 C. diphtheriae isolates from preadolescent children with endocarditis obtained in July and August 2015 (Table 1)
One probable case occurred in a patient who was linked to a carrier of toxigenic C. diphtheriae and died; the postmortem throat swab from this patient was culture negative
Summary
Mignon du Plessis, Nicole Wolter, Mushal Allam, Linda de Gouveia, Fahima Moosa, Genevie Ntshoe, Lucille Blumberg, Cheryl Cohen, Marshagne Smith, Portia Mutevedzi, Juno Thomas, Valentino Horne, Prashini Moodley, Moherndran Archary, Yesholata Mahabeer, Saajida Mahomed, Warren Kuhn, Koleka Mlisana, Kerrigan McCarthy, Anne von Gottberg. In 2015, a cluster of respiratory diphtheria cases was reported from KwaZulu-Natal Province in South Africa. Two novel lineages were identified, namely, toxigenic sequence type (ST) ST-378 (n = 17) and nontoxigenic ST-395 (n = 3). Molecular epidemiology can be used for investigating diphtheria case clusters in the postvaccine era to improve our understanding of patterns of transmission and spread of epidemic clones. The highly discriminatory, clustered, regularly interspaced short palindromic repeats (CRISPR) spoligotyping was used for a more detailed analysis of the Russia epidemic clone [6]. In South Africa, early studies in the 1940s and 1950s reported rates of respiratory diphtheria significantly higher than those in industrialized countries, ranging 20–35 cases/100,000 population and equating to ≈3,000 case notifications annually [7,8].
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