Performance comparison of three commercial multiplex molecular panels for respiratory viruses at a South African academic hospital.

Background: Respiratory infections are a major contributor to hospital admissions. Identification of respiratory pathogens by means of conventional culture and serology methods remains challenging. Multiplex molecular assays are an appealing alternative that endeavours to be rapid, more accurate and less arduous. Objective: The study aimed to compare the clinical performance of three commercial multiplex molecular assays for respiratory viruses. Methods: Forty-eight respiratory specimens obtained from patients at Tygerberg Hospital in the Western Cape province of South Africa were studied. These specimens were collected between May 2020 and August 2020. The results of the Seegene Anyplex™ II RV16, FilmArray® Respiratory 2.1 plus Panel (FARP), and QIAstat-Dx® Respiratory SARS-CoV-2 Panel (QRP) were analysed based on the overlapping targets. A composite reference standard was applied to provide a standard reference for comparison. Results: The overall sensitivity of the Seegene Anyplex™ II RV16 was 96.6% (57/59), the FARP 98.2% (56/57) and the QRP 80.7% (46/57). The overall specificities were 99.8% (660/661), 99.0% (704/711) and 99.7% (709/711), respectively. The QRP failed to detect coronaviruses and parainfluenza viruses in 41.7% (5/12) and 28.6% (4/14) of positive specimens, respectively, while the FARP produced the lowest target specificity of 88.4% (38/43) for rhinovirus/enterovirus. Conclusion: The overall specificity of all three platforms was comparable; however, the sensitivity of the QRP was inferior to that of the ARV and FARP. What this study adds: This study adds to the body of performance characteristics described for respiratory multiplex panels, especially in the African context where molecular diagnostics for infectious diseases are gaining momentum.

The Surgical Outcome of Infective Endocarditis in South Africa over 10 Years: A Retrospective Review.

Objectives: There is a paucity of data on the outcome of left-sided cardiac valve surgery for infective endocarditis in South Africa. It is hypothesized that outcomes may be poorer compared to international standards due to differences in disease burden, timing of surgery, organism prevalence, and co-morbidities. Method: This is a retrospective study of 160 patients with left heart valve endocarditis who underwent cardiac surgery from January 2010 to December 2019. Demographic, operative, and admission-related parameters were assessed to determine their association with all-cause mortality during the early post-operative (<30 days) and late post-operative (>30 days) periods. Results: Early post-operative mortality (<30 days) was 8.8% and late post-operative mortality (>30 days) was 13.1%. Late survival showed 77.5% of the patients were alive with a mean follow-up period of 41 months. Increased age (p = 0.04), critical illness (p < 0.001), and higher urgency of intervention (p < 0.001) were associated with higher early post-operative mortality. Peri-operative organ failure, including cardiac (p = 0.025), renal (p = 0.016), and respiratory failure (p < 0.001), contributed significantly to both early and late mortality. Pre-operative antibiotics for fewer days (p = 0.024), ongoing sepsis (p = 0.022), and para-valvular extension (p = 0.046) were associated with higher early mortality. Conclusions: Infective endocarditis is a common indication for cardiac valve surgery in South Africa. Goal-directed medical management and clinical optimization prior to surgery were crucial to achieving better outcomes. Salvage procedures and critical illness with organ failure prior to surgery were associated with poorer outcomes. Despite unique challenges, cardiac surgery for infective endocarditis at Tygerberg Hospital compares favorably to international standards.

Non-toxigenic Corynebacterium diphtheriae endocarditis: A cluster of five cases.

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.