Factors Associated with Severe Sepsis or Septic Shock in Patients with Gram Negative Bacteraemia: An Observational Cohort Study

Introduction: Sepsis is a systemic, host response to infection that progresses from sepsis to severe sepsis to septic shock. Severe sepsis carries significant morbidity and mortality. In the presence of individual risk factors such as old age, diabetes mellitus, chronic liver and renal disease, the death rate remains high despite treatment with antimicrobial agents. Aim: To determine the factors associated with severe sepsis or septic shock and to identify the factors influencing the mortality among patients with gram-negative bacteraemia. Materials and Methods: In this observational cohort study, 219 patients with gram-negative bacteraemia were screened for the presence of sepsis, severe sepsis and septic shock and detailed characteristics of the patients were analysed using independent sample t-test, chi-square test and logistic regression. Results: Among 219 patients with gram-negative bacteraemia, 43 (19.6%) were classified as severe sepsis, 69 (31.5%) as septic shock and the remaining 107 (48.9%) as only sepsis according to clinical criteria. Diabetes mellitus (p-value=0.006), chronic liver disease (p-value=0.001), presence of urinary catheter (p-value<0.001) and organisms other than E. coli (p-value=0.036) had a significant association with severe sepsis. Mortality was observed in 82 (73.3%) patients with severe sepsis and septic shock. The factors that predicted mortality among patients with gram-negative bacteraemia were age >= 65 years, chronic liver disease, indwelling urinary catheter, endotracheal and nasogastric tube, central venous access, organisms other than E. coli, respiratory and abdominal sources of infection. The mean Pitt bacteraemia score of >4 was significant (p-value <0.001) for development of severe sepsis and septic shock and mortality was higher in those with high scores. (p-value <0.0001). Conclusion: The present findings suggest that diabetes mellitus, chronic liver disease, indwelling urinary catheter and organisms other than E. coli are important risk factors for the development of severe sepsis or septic shock. Patients with higher Pitt bacteraemia score may have higher risk of death.