COMPARATIVE EVALUATION OF BLOOD CULTURE BY CONVENTIONAL METHOD AND BACTEC USING BLOOD SAMPLES OF ICU PATIENTS and ANTIBIOGRAM OF ISOLATED PATHOGENS

Abstract

Introduction: Sepsis is the leading cause of death in Intensive ICU patients worldwide.Blood
cultures are the 'gold standard' for identifying pathogens causing septicemia and in directing
appropriate antibiotic therapy.The present study was aimed to compare sensitivity of
automated BACTEC 9120 blood culture system and conventional blood culture method in
identifying true pathogenic organism, to compare the time needed for the detection of
microorganisms by conventional method of blood culture and by automated BACTEC 9120
blood culture system and to evaluate the susceptibility pattern of antibiotics for pathogens
isolated.
Material and Methods: Study was done over a period of one year from April 2015 to March
2016. A total of 636 blood samples were collected andsubjected to blood culture by BACTEC
9120 and conventional method. The statistical tests applied were Sensitivity, Specificity,
Positive predictive value, Negative predictive value, T-test and kappa statistics.
Results: Out of 636 blood samples clinically significant isolates were recovered from 85
samples by BACTEC, of which 74 were bacterial pathogens and 11 were candida. In
conventional method out of 80 significant isolates 69 were bacterial and 11 were candida.
Gram positive (majority Staphylococci) were more commonly isolated than Gram negative
(majority Acinetobacter and E.coli). Mean time to detect was 19.47 hours and 3.02 days, by
BACTEC 9120 and conventional method respectively. Vancomycin, Teicoplanin and
Linezolid were found to be the most effective (100%) for gram positive bacteria and for gram
negative bacteria Colistin (70-100%), Polymyxin-B (70-100%) were the most effective.
Conclusion: Sepsis is associated with prolonged hospital stay, increased costs and with a high
mortality. The use of BACTEC BD blood culture system is better for rapid identification of
blood borne pathogens followed by determining actual antimicrobial treatment in the scenario
of multi drug resistance so as to improve patient's outcome.