Microbiology Research Journal International

Background and Aims: Infective endocarditis is a serious cause of morbidity and mortality among patients with cardiovascular disorders that are either congenital or rheumatic in origin. Very few studies are available from our region describing the causes and outcomes of patients with infective endocarditis. The current study aimed to determine the bacterial causes and antimicrobial susceptibility patterns of the isolates to support better treatment outcomes in this population.

Study design: It was a prospective cross-sectional observational study.

Place and Duration of Study: The study was conducted between July 2023 and June 2025 in the Department of Microbiology, R.G. Kar Medical College and Hospital, Kolkata, and included samples from the Departments of Medicine, Cardiology, and Cardiovascular Surgery.

Methodology: We included 85 patients (41 male and 44 female; age range 1.5-78 years) with definite infective endocarditis who had a previous history of rheumatic heart disease or a congenital heart anomaly, a positive blood culture or echocardiographic evidence of vegetations on the heart valves, and were undergoing treatment for cardiac infection or heart failure. Blood cultures were performed for patients with signs of infection, and heart valves with vegetations or abscesses removed during cardiovascular surgery were also cultured to detect the different bacterial causes of infective endocarditis.

Results: The mean age of the patients was 41.93 years, with a male-to-female ratio of 1:1.07. The majority (95.3%) had native-valve infective endocarditis. Most cases (65.88%) occurred in the 20-50-year age group. Rheumatic heart disease was a common underlying cause, and the mitral valve was frequently affected. Methicillin-resistant Staphylococcus aureus (MRSA) was the most common bacterial cause (46.5%), followed by Pseudomonas species (11.62%). Cultures were positive in 45.88% of patients, with single or multiple isolates (43 isolates in total), and the in-hospital mortality rate was 3.53%. Fever was a common symptom (63.52%). Vancomycin and linezolid for Gram-positive microorganisms, and levofloxacin, cotrimoxazole, and polymyxin B for Gram-negative microorganisms, showed good in vitro susceptibility.

Conclusion: Although infective endocarditis remains challenging because of its high morbidity and mortality, improvements have been observed through a multidisciplinary approach to both diagnosis and treatment. Medical treatment should consider the common microorganisms and their susceptibility patterns, and surgery may be required in cases with complications.