Microbiological and clinical profile of infective endocarditis patients: An observational study experience from tertiary care center Karachi Pakistan

Background: The study analyzed microbiological and antimicrobial susceptibility profile of organisms isolated from patients with infective endocarditis (2015-17) and compared disease outcomes in cohorts of endocarditis patient with history of prior invasive vascular intervention (high risk group) vs those without (native valve group). We hypothesized that high risk group would be more likely to have severe disease outcomes. Methods: This was a prospective cohort study (2015-17). All blood and cardiac tissue samples of enrolled patients suspected of endocarditis according to modified Duke's criteria were followed for microbiological and antimicrobial susceptibility profile. The high risk group was compared with the native valve group with 90day follow up to determine difference in clinical course and outcome in terms of disease severity (defined as any patient with endocarditis undergoing surgical management, readmission or dying). The data was analyzed using SPSS 21.0 software and chi-square test. 90day mortality was calculated using Kaplan Meier survival curves. Results: Total 104 patients with endocarditis were enrolled. Overall culture positivity rate was 71.2%. Streptococcus species were the most common isolate (36.7%), followed by S. aureus (17.3%) cases. In Streptococcus species, 14.2% showed intermediate susceptibility to penicillin. Thirty six patients were included in the cohort analysis. A poor outcome was seen in 85.7% high risk group as compared to 50% of native valve group. The overall mortality rate was 19.4%. Conclusions: We found Streptococcus species to be the predominant pathogen for endocarditis overall. However Staphylococcus aureus predominated native valve group. High risk group showed more complicated clinical course.