Abstract
BackgroundSpeeding up identification and antimicrobial susceptibility testing (AST) is of foremost importance in the management of blood cultures. Here, we describe a simple, rapid, and standardized approach based on a very short-term incubation on solid medium from positive blood cultures followed by MALDI-TOF mass spectrometry identification and automated AST. The aim of the study was to evaluate the impact in the laboratory practice of this new procedure with respect to that previously used (standard method) by comparing TAT and cumulative percentage of final reports to clinicians.ResultsCompared with the standard method, the new procedure gave correct organism identification at genus or species level in 98.4% of monomicrobial samples. AST resulted in 97.7% essential agreement and 98.1% categorical agreement, with 0.9% minor errors, 1.0% major error, and 1.5% very major errors. The mean turnaround time to identification and AST was 61.4 h by using the new method compared to 83.1 h by using standard procedure. Concerning cumulative percentages of final reports, approximately a third of results were available at 48 h from the check-in of the sample when using the new procedure, whereas no final reports were ready at the same time with the standard method.ConclusionsThe new procedure allows faster and reliable results using a simple and standardized approach. Thus, it represents an important tool for a more rapid management of blood cultures when molecular methods are not available in the laboratory.
Highlights
Speeding up identification and antimicrobial susceptibility testing (AST) is of foremost importance in the management of blood cultures
turnaround time (TAT) resulting in the second period was evaluated in comparison with that obtained in the first period
The new procedure allowed to obtain a correct identification at the species level in 187
Summary
Speeding up identification and antimicrobial susceptibility testing (AST) is of foremost importance in the management of blood cultures. Blood culture is the gold standard method for the diagnosis of BSIs, and it is included among the early activities in the Surviving Sepsis Campaign guidelines [1] It is time-consuming and usually takes on average 24–48 h for microbial growth in blood culture bottles, and further 48 h for identification and antimicrobial susceptibility tests after growth in solid culture media [2]. Speeding up these procedures is of foremost importance in the management of bloodstream infections, leading to rapid administration of adequate antimicrobial therapy or adjusting ongoing treatment, and so improving outcome in patients with bacteremia [3]. Molecular methods require additional hands-on processing time and costs [7, 8]
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