Impact of the blue-carba rapid test for carbapenemase detection on turnaround time for an early therapy against Pseudomonas aeruginosa.

Background: To determine the turnaround time from a blue-carba result until a final microbiological report (bacterial identification plus antimicrobial susceptibility profile) and to infer the impact of an early therapeutic intervention based on the blue-carba results.

Methods: Pseudomonas aeruginosa isolates were recovered from hospitalized patients from Porto Alegre, Brazil, and tested by blue-carba test. Time required for a blue-carba result, right after the sample processing, was compared with those required to get final report (specie identification and antimicrobial susceptibility profile) Isolates blue-carba positive were tested by phenotypically and genotypically for Klebsiella pneumoniae carbapenemase and metallo-β-lactamase genes.

Results: A total of 199 isolates were analyzed and 23 (11.6%) were blue-carba positive and harboring the bla gene. Fifty-two (26.1%) isolates were blue-carba negative but resistant to meropenem and/or imipenem. Polymyxin B and ceftolozane/tazobactam (this latter except for SPM-1 producers) were 100% active for all P. aeruginosa isolates, a blue-carba test allow an earlier intervention or adequacy of therapy.

Conclusions: Early adequacy can be promoted by blue-carba test for 11.6% of SPM-1-producing P. aeruginosa isolates, polymyxin B could be prior associated and ceftolozane/tazobactam withdrawn from therapy. For the remaining isolates, empirical therapy involving ceftolozane/tazobactam can be maintained with greater likelihood of adequacy. An active communication between laboratory and clinical services is necessary to better explore these earlier blue-carba results, significantly reducing the time for a first intervention.