Direct susceptibility testing by disk diffusion on positive BacT/ALERT blood cultures: A rapid and definite tool for antibiotic stewardship

Original Article

Author Details : V Lokeshwari, Sandhya Bhat K*, Vaishnava Devi

Volume : 7, Issue : 3, Year : 2021

Article Page : 179-185

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Introduction: Blood stream infections continue to be the major cause of mortality and morbidity and hence early availability of direct susceptibility reports can be lifesaving. This study aims to ascertain if direct susceptibility testing (DST) can be used as a diagnostic tool in bacteremic patients and to correlate the results of both DST and standard antimicrobial susceptibility reports (AST), thereby serving to benefit both the patients and also to reduce the irrational use of antibiotics.
Materials and Methods: An experimental study was carried out after obtaining waiver of consent, in a tertiary care centre. A total of 37 patients were included in the study after careful consideration of the inclusion and exclusion criteria. Gram staining report, bacteriological profile, direct susceptibility report, antimicrobial susceptibility report of all the isolates were documented. Statistical analysis was done by using IBM SPSS software.
Results: Overall prevalence of sepsis was 40.5%. Gram negative bacteria were more commonly isolated (83.8) and Escherichia coli was the commonest isolate (51.4%). The antimicrobial resistance was observed maximum for amoxicillin/clavulanic acid (66.7%), ceftriaxone (60.6%), Cefotaxime (57.6%) and least for meropenem (9.1%), imipenem (6.1%). On comparison of DST with AST among 28 gram-negative Enterobacteriaceae isolates 15 minor errors (4.8%) and three major errors (0.97%) were recorded, with maximum errors being documented for piperacillin/tazobactam with five minor errors (17.9%) and one major error (3.6%).
Conclusion: DST is an important tool for early institution of targeted therapy and should be considered as one of the step towards antibiotic stewardship intervention.

Keywords: Blood stream infection, Blood culture, Direct susceptibility test, Disk diffusion

How to cite : Lokeshwari V, Sandhya Bhat K, Devi V , Direct susceptibility testing by disk diffusion on positive BacT/ALERT blood cultures: A rapid and definite tool for antibiotic stewardship. IP Int J Med Microbiol Trop Dis 2021;7(3):179-185

Copyright © 2021 by author(s) and IP Int J Med Microbiol Trop Dis. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License (

Article History

Received : 30-04-2021

Accepted : 29-07-2021

Available online : 07-09-2021

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