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Improved blood culture workflow for faster identification of KPC-producing Enterobacterales

  • Seco, Bruna Mara Silva1, 2, 3
  • Campos, Juliana Coutinho1
  • da Costa Rocha, Darlan Augusto1
  • de Lima, Aline Valerio1
  • de Oliveira, Fernanda Filomena2
  • Lemo, Mara Elisa Borsato2
  • Sampaio, Suely Carlos Ferreira4
  • Sampaio, Jorge Luiz Mello1, 2
  • 1 University of São Paulo, School of Pharmacy, Clinical Microbiology and Antimicrobial Resistance Laboratory, Av. Professor Lineu Prestes, 580, São Paulo, SP, Zip code 05508-900, Brazil , São Paulo (Brazil)
  • 2 Fleury Medicine and Health, Microbiology Section, São Paulo, Brazil , São Paulo (Brazil)
  • 3 Max Planck Institute of Colloids and Interfaces, Department of Biomolecular Systems, Arnimallee 22, Berlin, 14195, Germany , Berlin (Germany)
  • 4 Santa Casa de São Paulo School of Medical Sciences, São Paulo, Brazil , São Paulo (Brazil)
Published Article
Brazilian Journal of Microbiology
Springer International Publishing
Publication Date
Dec 06, 2018
DOI: 10.1007/s42770-018-0037-y
Springer Nature


Carba-NP original report for blood cultures described the need of subculture and mechanical lysis before testing, reaching the turnaround time of approximately 4 hours for sample preparation. We tested 100 consecutive blood cultures positive for Gram-negative bacilli on the Gram stain from a large clinical laboratory. Bacterial pellets were prepared by centrifugation and submitted to Carba-NP and Blue-Carba tests and used further to prepare smears for Vitek MS. Results obtained with colonies grown on sheep blood agar using the same methodologies were used as the gold standard. Carbapenemase genes were confirmed by PCR and DNA sequencing. Vitek MS identified correctly 86% of the samples. Of note, 7% of the samples were incorrectly reported by the instrument as containing a single isolate. KPC-2 was the predominant carbapenemase detected. There was 100% concordance for both negative and positive results for Carba-NP. In contrast, for Blue-Carba the concordance for positive results was 92.8%, and 41% of strains negative for carbapenemases presented a yellowish color on control well turning the test non-interpretable. The turnaround time for sample preparation for preparing the pellet was 13 min, and no subculture or mechanical lysis is needed when detecting KPC production in Enterobacterales.

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