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Original Research
Non-toxigenic Corynebacterium diphtheriae endocarditis: A cluster of five cases
Submitted: 18 May 2023 | Published: 21 February 2024
About the author(s)
Tamsin Lovelock, Division of Infectious Diseases, Department of Medicine, Faculty of Health Sciences, Stellenbosch University and Tygerberg Hospital, Cape Town, South AfricaMignon du Plessis, Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, Johannesburg, South Africa; and School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
Clinton van der Westhuizen, Department of Medical Microbiology, Tygerberg Hospital, National Health Laboratory Service, Cape Town, South Africa; and Division of Medical Microbiology and Immunology, Department of Pathology, Tygerberg Hospital/Stellenbosch University, Cape Town, South Africa
Jacques T. Janson, Division of Cardiothoracic Surgery, Department of Surgery, Tygerberg Hospital/Stellenbosch University, Cape Town, South Africa
Charlene Lawrence, Western Cape Government, Department of Health and Wellness, Emergency and Clinical Services Support, Service Priorities Coordination, Communicable Disease Control and Outbreak Response, Cape Town, South Africa
Arifa Parker, Division of Infectious Diseases, Department of Medicine, Faculty of Health Sciences, Stellenbosch University and Tygerberg Hospital, Cape Town, South Africa
Alfonso Pecoraro, Division of Cardiology, Department of Medicine, Stellenbosch University and Tygerberg Hospital, Cape Town, South Africa
Hans Prozesky, Division of Infectious Diseases, Department of Medicine, Faculty of Health Sciences, Stellenbosch University and Tygerberg Hospital, Cape Town, South Africa
Anne von Gottberg, Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, Johannesburg, South Africa; and School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
Jantjie Taljaard, Division of Infectious Diseases, Department of Medicine, Faculty of Health Sciences, Stellenbosch University and Tygerberg Hospital, Cape Town, South Africa
Abstract
Background: Classical toxin-mediated respiratory diphtheria has become less common because of widespread effective vaccination globally but invasive disease as a result of non-toxigenic strains of Corynebacterium diphtheriae is not prevented by vaccination and may result in severe disease, including infective endocarditis (IE).
Objectives: To describe the outbreak and subsequent investigation of a cluster of five cases of non-toxigenic C. diphtheriae endocarditis.
Method: A retrospective observational case series of five cases of non-toxigenic C. diphtheriae endocarditis identified in the rural West Coast district of the Western Cape province of South Africa between May 2021 and June 2021.
Results: Non-toxigenic C. diphtheriae IE had an aggressive clinical course with high mortality in this cohort. Only one of five patients survived to hospital discharge. The surviving patient received a prompt diagnosis with early surgical intervention but still had a complicated clinical course. Notably, only one case had a pre-existing risk factor for IE, namely a prosthetic valve. Whole genome sequencing of clinical isolates confirmed that all isolates were of the same novel sequence type of non-toxigenic C. diphtheriae but despite a thorough investigation no epidemiological link was ever found between the cases.
Conclusion: Non-toxigenic strains of C. diphtheriae are less well known but may be highly virulent and cause severe invasive disease.
Contribution: This is the largest cluster of non-toxigenic C. diphtheriae IE ever described in South Africa and expands the body of literature on this unusual but possibly emerging infection.
Keywords
Sustainable Development Goal
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