Rapid immunochromatographic detection of carbapenemases directly from positive blood cultures in patients colonized by carbapenemase-producing bacteria.

Objectives: Carbapenem resistance is increasing worldwide. Earlier detection of this resistance, combined with appropriate treatment, could improve the prognosis of bloodstream infection. This study aims to evaluate the detection of carbapenemase producing gram-negative bacteria directly from positive blood cultures to quickly adapt antibiotic therapy before the results of antibiotic susceptibility testing are available.

Method: A prospective single-center study was conducted over a five-month period at Lille University Hospital. Carbapenemase detection by immunochromatographic testing was performed directly from positive blood cultures with gram-negative rods of thirty-five patients previously colonized with carbapenemase-producing bacteria.

Results: Among these thirty-five positive blood cultures, 15 carbapenemase-producing strains were directly detected, mainly OXA-48 and NDM. This rapid procedure provided results in less than one hour, compared to several hours for conventional methods. Of the patients with infections caused by carbapenemase-producing isolates, 67% (10 patients) received inappropriate empiric treatment, highlighting the potential of the rapid test to adjust antibiotic therapy sooner.

Conclusions: Carbapenemase detection by immunochromatographic testing directly on blood culture pellets is reliable and can lead to early adaptation of antibiotic therapy in these severe infections.