Infective endocarditis in Africa: an urgent call for more data
Authors: Alfonso J Pecoraro, Philip G Herbst, Anton F Doubell
Journal: The Lancet Global Health (2021)

Infective endocarditis has a high incidence of morbidity and mortality that has stimulated research, generating excellent data from high-income countries. In contrast, a paucity of data exists for the condition in low-income and middle-income countries.1Pecoraro AJ Doubell AF Infective endocarditis in South Africa.Cardiovasc Diagn Ther. 2020; 10: 252-261Google Scholar The consequence of the paucity of data, specifically prospective data for infective endocarditis in low-income and middle-income countries, is that these countries continue to use guidelines2Habib G Lancellotti P Antunes MJ et al.2015 2015 ESC Guidelines for the management of infective endocarditis: The Task Force for the Management of Infective Endocarditis of the European Society of Cardiology (ESC). Endorsed by: European Association for Cardio-Thoracic Surgery (EACTS), the European Association of Nuclear Medicine (EANM).Eur Heart J. 2015; 36: 3075-3128Google Scholar derived from predominantly high-income countries to guide patient management in a resource-limited setting. Recent publications have highlighted the important differences in the characteristics of infective endocarditis when comparing this condition in high-income countries with low-income and middle-income countries.1Pecoraro AJ Doubell AF Infective endocarditis in South Africa.Cardiovasc Diagn Ther. 2020; 10: 252-261Google Scholar, 3Cahill TJ Prendergast BD Infective endocarditis.Lancet. 2016; 387: 882-893Google Scholar In The Lancet Global Health, Jean Jacques Noubiap and colleagues4Noubiap JJ Nkeck JR Kwondom BS Nyaga UF Epidemiology of infective endocarditis in Africa: a systematic review and meta-analysis.Lancet Glob Health. 2022; 10: e77-e86Google Scholar summarise the current available data for infective endocarditis in Africa. Their systematic review highlights the paucity of available data and includes only five prospective studies in the meta-analysis. The analysis suggests that infective endocarditis in Africa, in contrast to data from high-income countries, is a disease of young patients with few comorbidities and higher rates of underlying rheumatic heart disease. Although the predominance of Staphylococcus aureus mimics data from high-income countries, the viridans group of streptococci is more prevalent in Africa than in cohorts from high-income countries.5Habib G Erba PA Lung B Clinical presentation, aetiology and outcome of infective endocarditis. Results of the ESC-EORP EURO-ENDO (European infective endocarditis) registry: a prospective cohort study.Eur Heart J. 2019; 40: 3222-3232Google Scholar The high rate of viridans streptococci-associated infective endocarditis (27·5%) is possibly due to a combination of the endemic status of rheumatic heart disease (52·0%) coupled with poor oral health observed in a substantial proportion of patients. In our own experience, the viridans streptococci are an unlikely cause of infective endocarditis in patients with no predisposing endocardial abnormality. A unique feature of infective endocarditis in Africa is the very high rates of blood culture-negative infective endocarditis reported from multiple centres. The authors suggest possible causes of the high rates of blood culture-negative infective endocarditis including inadequate blood culture sampling and sterilised blood cultures due to commencement of antimicrobial therapy before blood culture sampling. An important contributor to the high rates of blood culture-negative infective endocarditis, not reflected in this analysis, is the emergence of non-culturable or difficult to culture organisms.6Pecoraro A Herbst P Pienaar C et al.Bartonella species as a cause of culture-negative endocarditis in South Africa.Eur J Clin Microbiol Infect Dis. 2021; 40: 1873-1879Google Scholar, 7Fournier P Thuny F Richet H et al.Comprehensive diagnostic strategy for blood culture-negative endocarditis: a prospective study of 819 new cases.Clin Infect Dis. 2010; 51: 131-140Google Scholar These organisms vary according to geographical location, but the available evidence would suggest that the Bartonella species are the most common in Africa.6Pecoraro A Herbst P Pienaar C et al.Bartonella species as a cause of culture-negative endocarditis in South Africa.Eur J Clin Microbiol Infect Dis. 2021; 40: 1873-1879Google Scholar, 8Tasher D Raucher-Sternfeld A Tamir A Giladi M Somekh E Bartonella quintana, an unrecognized cause of infective endocarditis in children in Ethiopia.Emerg Infect Dis. 2017; 23: 1246-1252Google Scholar, 9Moodley VM Zeeman MTS van Greune CHJ Corcoran C Culture-negative endocarditis due to Bartonella quintana.S Afr Med J. 2016; 106: 470-471Google Scholar Serology to detect active infection with these difficult-to-culture organisms as well as broad range PCR of valve tissue to detect 16S rRNA for bacteria and ITS2 for fungi was only performed in a small number of the studies included. This limitation might have contributed to the observation that in more than half of the patients a causative organism was not identified. Future studies should evaluate the effect of a set protocol for organism detection,2Habib G Lancellotti P Antunes MJ et al.2015 2015 ESC Guidelines for the management of infective endocarditis: The Task Force for the Management of Infective Endocarditis of the European Society of Cardiology (ESC). Endorsed by: European Association for Cardio-Thoracic Surgery (EACTS), the European Association of Nuclear Medicine (EANM).Eur Heart J. 2015; 36: 3075-3128Google Scholar, 6Pecoraro A Herbst P Pienaar C et al.Bartonella species as a cause of culture-negative endocarditis in South Africa.Eur J Clin Microbiol Infect Dis. 2021; 40: 1873-1879Google Scholar on the number of patients with infective endocarditis where no organism is detected. Such a protocol should be similar to those used in high-income countries but with a specific focus on locally prevalent organisms. Given the young age and few comorbidities of patients with infective endocarditis in this pooled analysis, the in-hospital mortality rate (22·6%) reported is higher than expected, and substantially higher when compared with the in-hospital mortality rate of patients in the European Infective Endocarditis registry (17·1%).5Habib G Erba PA Lung B Clinical presentation, aetiology and outcome of infective endocarditis. Results of the ESC-EORP EURO-ENDO (European infective endocarditis) registry: a prospective cohort study.Eur Heart J. 2019; 40: 3222-3232Google Scholar The higher mortality rate in Africa is likely to be the result of multiple factors including the high rates of blood culture-negative infective endocarditis, limited access to timeous surgery, and high rates of prosthetic valve endocarditis. Although the rates of surgery were similar when compared with high-income countries, data for the timing of surgery and the surgical strategy used is not available. Early surgical intervention, in particular early valvular repair surgery, in patients with a guideline indication for surgery, has an important role in preventing complications.1Pecoraro AJ Doubell AF Infective endocarditis in South Africa.Cardiovasc Diagn Ther. 2020; 10: 252-261Google Scholar, 2Habib G Lancellotti P Antunes MJ et al.2015 2015 ESC Guidelines for the management of infective endocarditis: The Task Force for the Management of Infective Endocarditis of the European Society of Cardiology (ESC). Endorsed by: European Association for Cardio-Thoracic Surgery (EACTS), the European Association of Nuclear Medicine (EANM).Eur Heart J. 2015; 36: 3075-3128Google Scholar Timing of surgery and surgical strategy was not reported in this analysis, but it is possible that the majority of patients underwent mechanical valve replacement due to the high prevalence of rheumatic heart disease and the young age at presentation. Access to early surgery is often limited in low-income and middle-income countries and this could also have contributed to the higher-than-expected mortality rate. In summary, the current work by Noubiap and colleagues highlights the paucity of data for infective endocarditis in Africa and reveals important similarities and differences in the characteristics of this condition in Africa when compared with high-income countries. Therefore, an urgent need exists for prospective data specific to infective endocarditis on the African continent to customise protocols for organism detection, update empirical therapy for infective endocarditis, and guide decision making in terms of timing of surgery as well as deciding on the optimal surgical strategy. We declare no competing interests. Epidemiology of infective endocarditis in Africa: a systematic review and meta-analysisAs the most prevalent risk factor in Africa, rheumatic heart disease should be central in interventions to reduce the burden of infective endocarditis on the continent. In tertiary hospitals with good access to cardiac surgery, the outcomes of infective endocarditis seem relatively similar to what has been reported in other parts of the world, especially in high-income countries. Full-Text PDF Open Access