Title : Utility of limulus amebocyte lysate assay as a diagnostic aid in patients with sepsis
Abstract:
Abstract-
Background-Bacterial sepsis is a common medical illness and is associated with high mortality. Gold standard for the diagnosis of sepsis is culturing from blood or other body fluids which is of unsatisfactory yield. However, culture positivity in severe sepsis is 40%. Limulus amebocyte lysate (LAL) assay detects the lipopolysaccharide on the cell wall of Gram-negative bacteria and is an appealing principle for the diagnosis of sepsis.
Objective- This was a pragmatic study which was done to find out the utility of LAL assay in the identification of patients with sepsis.
Methodology-This study included 55 admitted patients with clinical sepsis and 42 controls (no sepsis but admitted for other conditions). Patients who were above the age of 18 years with a clinical diagnosis of sepsis were included in this study. Patients with primary immune system disorders, those who had received immunoglobulin or heparin were excluded from the study. Four groups of patients were studied. Group A included patients with possible gram-negative sepsis, group B had patients with possible gram-positive sepsis, group C included patients with sepsis due to unknown cause and group D had patients without any infection (control group). The study was carried out at a tertiary teaching hospital in south India over a period of 2 years. Blood samples and relevant body fluids were collected from all the study subjects and LAL test was performed by the gel-clot technique.
Results-5 subjects in the groups with sepsis and 1 subject in the control group were found to be positive on LAL assay. After analysis of the LAL assay and the culture results, true positive was found in 1 case, and false positives were found in 5 cases. False negative results were seen in 36 cases and true negative results were seen in 55 cases. The sensitivity of LAL assay was calculated to be 2.7% and specificity was found to be 91.67%. The positive predictive value of LAL was found to be 16.67% while the negative predictive value was 60.44%.
Conclusion-LAL assay was not found to be useful as a diagnostic aid in patients with sepsis and needs improvised technology for future application.
