A Comparative Study of Conventional and Automated Blood Culture System in Adult Patients

Abstract

Introduction: Blood culture is considered as the gold standard for the diagnosis of bloodstream infection. Conventional blood culture system is less sensitive and takes longer duration for the detection of bloodstream infections whereas automated blood culture system is more sensitive and rapid in detecting causative organisms of bloodstream infections. This prospective study was undertaken to compare the automated blood culture system with the conventional blood culture system for the identification of microbial pathogens in bloodstream infections. Method: This prospective study was done in Department of Microbiology, Silchar Medical College & Hospital, Silchar for a period of 7 months from November 2021 to May 2022. Blood samples from the patients were inoculated into BD BACTEC Plus Aerobic culture vials for automated blood culture system and Brain Heart Infusion broth for conventional blood culture system. Positive bottles flagged by the automated machine were isolated and identified by doing routine subcultures on Blood agar and MacConkey agar and necessary biochemical tests. The conventional blood culture bottles were processed as per standard protocols. Result: Out of 123 samples, 21(17.09%) showed culture positivity by automated blood culture method and 15(12.19%) showed culture positivity by conventional blood culture method. The most common isolate was Staphylococcus aureus followed by Escherichia coli in automated method whereas the most common isolate in conventional method was Staphylococcus aureus followed by Klebsiella pneumoniae. Conclusion: This study concluded that automated blood culture method is more sensitive than conventional method and detects the presence of microorganisms rapidly causing bloodstream infections. Keywords: Bloodstream infection, Automated blood culture, Conventional blood culture