Time to positivity of blood culture as a prognostic marker in predicting the clinical outcome of blood stream infection

Abstract

Automated blood culture systems provide continuous monitoring of bacterial growth, and time to positivity (TTP), may be used as good tool for diagnosis of blood stream infections. Objective of the study was to document bacterial profile and their susceptibility pattern and to evaluate the association between the TTP and clinical outcome in patients with BSIs. A cross-sectional study was conducted (after obtaining waiver of consent from institute ethics committee), on 75 patients with positive blood culture. Laboratory data such as TTP, bacterial pathogen isolated from positive blood cultures and their susceptibility pattern, clinical parameters such as demographic characteristics, source of BSIs, severity of infection as per various clinical scores were analysed for patients with TTP ≤10 hours and > 10 hours using univariate analysis. was the commonest gram-negative bacterial isolate (33.3%), and Staphylococcus aureus was the commonest gram-positive bacterial isolate (22.2%). Antimicrobial resistance rate in GNB was very high for cefotaxime (57%), ciprofloxacin (44%) and among gram-positive bacterial isolates was high for clindamycin (56.5%), and cefotaxime (50%). In the study, median TTP was 13 hours and short TTP of ≤10h was observed for , and . There were statistically significant differences observed for end stage renal disease, diabetes association and neutropenia patients with short TTP. Time to positivity is a useful tool for to-measure laboratory prognostic factor for patients with bacteremia. However, further studies with larger sample size, may be required to define its usefulness and the optimal cut-off points.