NG-TEST CARBA 5 with BCP Kit detects 134 of 138 carbapenemases directly from spiked blood cultures
In a lab study on spiked blood cultures, a rapid test found five main carbapenemases in under 25 minutes with 97.10% sensitivity and 100% specificity.
A team led by Oueslati, Girlich and Naas evaluated a combination of the NG-TEST Blood Culture PREP (BCP) Kit and the NG-TEST CARBA 5 (NG Biotech) for direct detection of the five main carbapenemases from positive blood cultures. The results were published in Frontiers in Microbiology frontiersin.org
Frontiers in Microbiologyfrontiersin.orgOpen source ↗. The authors report that the workflow gives a result in under 25 minutes.
Rapid detection of Gram-negative carbapenemase-producing organisms (CPOs) in bloodstream infections is needed to guide timely therapy. The study was done on blood culture bottles spiked in the laboratory, not on samples from patients.
Panel and method
The researchers used 145 clinical Enterobacterales isolates to spike the bottles. Of these, 124 were CPOs with targeted carbapenemases: 18 NDM, 10 VIM, 28 IMP, 24 KPC, 31 OXA-48-like and 13 with multiple carbapenemases. Another 10 CPOs carried no targeted carbapenemases, and 11 isolates were non-CPOs.
The bottles were incubated in the BACT/ALERT VIRTUO system (bioMérieux) until the system detected bacterial growth. Bacteria were then prepared from the culture with the NG-TEST BCP Kit and tested with NG-TEST CARBA 5. The results were compared with those obtained from colonies frontiersin.org
Frontiers in Microbiologyfrontiersin.orgOpen source ↗.
Sensitivity and missed variants
The BCP Kit extracted bacteria reliably irrespective of species. NG-TEST CARBA 5 identified 134 of 138 carbapenemases from bacterial pellets from blood cultures and 136 of 138 from colonies. This corresponds to a sensitivity of 97.10% and 98.55%, respectively.
The KPC-31 and KPC-33 variants were missed in both pellets and colonies, as expected. Two VIM-producing Citrobacter freundii isolates were detected only from colonies.
CPOs without targeted carbapenemases and non-CPOs gave negative results, which gave 100% specificity frontiersin.org
Frontiers in Microbiologyfrontiersin.orgOpen source ↗. The authors conclude that the combination is a rapid, user-friendly, robust and accurate method for species-independent detection of the five main carbapenemases directly from positive blood cultures, enabling earlier targeted antimicrobial therapy.
