Recent Study Shows WASPLab® and VITEK®MS Together to Facilitate Positive Blood Culture Identification in Approximately 4 Hours

May 25, 2018

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Microbiology continues to see a rise in the adoption of automated specimen processors throughout its laboratories. The growing appeal is seen due to expected outcomes, such as improve patient care, faster turnaround times and reduced patient stay but to validate those expectations, studies are being conducted across the globe. One recent focus was presented as a poster during the 2018 AMMI Canada – CACMID Annual Conference in Vancouver, BC, Canada. The poster is entitled “Optimizing Time to Identifying Growth from Short Incubation Cultures Using WASPLab®” which set out to examine the best possible turnaround times for positively identifying sepsis in blood cultures.

The study took place at Mt. Sinai Hospital in Toronto, Canada and hypothesized that WASPLab® used in conjunction with VITEK®MS could allow for the rapid identification and turnaround time of positive blood cultures. The team set out to determine the answers to four main questions. The questions were: at what concentration does the blood culture read positive from the BACT/ALERT®VIRTUO (bioMerieux); how early could growth be detected and identified using WASPLab® and VITEK®MS; what are the optimal imaging times for the blood culture subcultures to test the shortening of turnaround time to identification; and finally, in the future, could laboratories successfully identify the blood cultures with short incubation cultures through WASPLab®?

To begin, first 52 prospective blood culture bottles at less than 3 hours of incubation that had flagged positive on the BACT/ALERT®VIRTUO® were diluted, with the colony counts performed using the spread plate method. The results found that the median blood cultures were flagged positive at a concentration of 4 x 10¹º cfu/I for Gram-positive cocci and 7 x 10¹¹ cfu/I for Gram-negative bacilli. Next 68 previously frozen clinical isolates of the most prevalent blood culture bacteria were processed by the WASPLab® at a 1×10¹¹ and 1×109 to reflect BACT/ALERT®VIRTUO® flagged concentrations. WASPLab® took high definition images at different incubation intervals between 0 – 48 namely 4, 10, 18 and 48 hours. Any visible growth was tested using VITEK®MS MALDI-TOF. Those results found that retrospective blood cultures could be identified properly as early as four hours! In addition, prospective blood cultures were examined, by processing 30 through WASPLab® immediately after being flagged positive by the BACT/ALERT®VIRTUO®. Prospective positive blood cultures were processed onto chocolate plates and incubated in WASPLab® at 37º with 5% CO2. The results of that study found that with prospective positive blood cultures visible growth could be detected and successfully identified as early as after 4 hours, as well!

In summary, the study found that WASPLab® used in combination with the VITEK® MS could allow for early and successful identification of positive blood cultures immediately after 4 hours of incubation.

This preliminary study is exciting news as the breadth of impact automation has on improving patient care continues to grow along with its potential. Getting those answers that matter to the patients who need them most is crucial. The great news is COPAN will be there every step of the way! Next step for this study is to verify AST from short incubation cultures. Request more information about WASPLab® today!