Direct testing by VITEK ® 2: A dependable method to reduce turnaround time in Gram-negative bloodstream infections.

CONTEXT: Bloodstream infections pose a major health-care burden worldwide. Routine microbiological methods are time-consuming, thereby delaying appropriate treatment.

AIMS: The aim of this study is to evaluate the method of direct testing of identification (ID) and antimicrobial susceptibility testing (AST) of positive blood culture bottles by VITEK® 2.

SETTINGS AND DESIGN: This was a prospective study at a tertiary level hospital.

SUBJECTS AND METHODS: One hundred positive BACTEC blood culture bottles with monomicrobial Gram-negative organisms on microscopy were tested in parallel by direct ID/AST as well as conventional method. Results obtained by two methods were compared in terms of ID/AST and turnaround time (TAT).

RESULTS: Of the 100 isolates tested, only one was misidentified by the direct method and there was no unidentified isolate. The AST results demonstrated 99.74% categorical and 99.65% essential agreement. Of 1144 organism-antibiotic combinations, there were 0.44% major error, no very major error, or minor error observed.

CONCLUSIONS: While conventional method is the gold standard, the direct ID/AST methods have demonstrated that it can be successfully utilized to decrease TAT to the final results by 18-24 h, without sacrificing test accuracy. This technique will help to tailor antimicrobial therapy, thereby reducing patient morbidity, mortality, and antibiotic resistance, as well.