Revisiting non-HACEK gram-negative endocarditis: Emerging clinical and microbiological trends from a prospective...

Non-HACEK gram-negative pathogens are an emerging cause of infective endocarditis (IE) with limited data from lower-middle-income countries. This study aimed to evaluate the clinical characteristics, treatment, and outcomes of non-HACEK gram-negative IE in an Indian cohort.

This prospective observational study was conducted in a tertiary care center in western India. Clinical presentation, microbiology, echocardiographic findings, and treatment outcomes of non-HACEK gram-negative IE were analyzed and compared with patients who had IE due to other etiology.

Among 121 patients with IE, 30 cases (24.8%) were due to non-HACEK gram-negative pathogens (median age: 48 years; 73.3% male). In this group, predisposing cardiac conditions were present in 56%, including prosthetic valves/devices in 26.6%. Pseudomonas aeruginosa was the most common etiology (n = 14, 46.6%), followed by E. coli (n = 6, 20%). The median vegetation size was 12 mm. Common complications included heart failure (56.7%), peripheral septic emboli (40%), and stroke (33.3%). Surgical intervention was performed in 23.3% of cases. The 60-day and 1-year mortality rates were 36% and 43.3%, respectively; relapse occurred in 11.8% of 1-year survivors. Compared to other etiology (n = 91), non-HACEK gram-negative IE had a significantly higher Charlson Comorbidity Index (2 vs 1, p = 0.035), persistent bacteremia (30% vs 12%, p = 0.02), and 60-day mortality (36.6% vs 17.6%, p = 0.032).

Non-HACEK gram-negative IE predominantly caused by Pseudomonas aeruginosa, is increasingly recognized. Compared to other etiology, Non-HACEK gram-negative IE was linked to higher comorbidity scores, frequent persistent bacteremia, and greater early mortality, highlighting its aggressive clinical course.