## Most Common Gram-Negative Organism in Sepsis **Key Point:** Escherichia coli (E. coli) is the most common organism isolated from blood cultures in sepsis globally and in India, accounting for approximately 20–30% of bacteraemic sepsis cases. **High-Yield:** E. coli is a gram-negative rod that originates from the gastrointestinal tract and is the leading cause of urinary tract infections, intra-abdominal infections, and healthcare-associated bacteraemia. ### Epidemiology of Sepsis in India In Indian cohorts, gram-negative organisms predominate in sepsis: - **E. coli** — most common (20–30%) - **Klebsiella pneumoniae** — second most common (10–15%) - **Staphylococcus aureus** — common in skin/soft tissue and device-related sepsis (10–12%) - **Pseudomonas aeruginosa** — less frequent in community-acquired sepsis; more common in ICU/nosocomial settings **Clinical Pearl:** The source of infection influences organism prevalence. E. coli dominates in urinary and intra-abdominal sources, which are the most common primary foci in sepsis. ### Why E. coli Leads 1. High prevalence in normal flora of GI tract 2. Frequent cause of UTI (most common source of sepsis in non-ICU settings) 3. Pathogenic strains carry virulence factors (fimbriae, lipopolysaccharide) 4. Common in community-acquired infections **Mnemonic:** **ESKAPE** organisms (Enterococcus, Staphylococcus aureus, Klebsiella, Acinetobacter, Pseudomonas, Enterobacter) are multidrug-resistant threats in ICU sepsis, but E. coli remains the single most frequent isolate overall.
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