Comparación de medios de cultivo para la detección de Legionella spp. en muestras de agua sanitaria: adaptación a la norma ISO 11731:2017

Abstract

IntroductionWater sample culturing is the reference method to detect Legionella spp. in sanitary facilities. Until 2017, UNE-EN ISO 11731 only included the GVPC medium, which inhibits interfering microbiota but hinders the growth of Legionella spp. To improve its recovery, the new standard incorporates the BCYE medium into the working protocol. MethodsWe inoculated 1,306 sanitary water samples onto BCYE and GVPC according to an accredited internal procedure. We compared the number of cfu/L of Legionella spp. detected in both media. ResultsThe median in BCYE was 2,000cfu/L higher than in GVPC (p=0.000). In the presence of high amounts of interfering microbiota, both media were similar; in the absence or low interfering microbiota BCYE was four times more sensitive than GVPC (p=0.000). ConclusionIncluding BCYE in the analysis of sanitary water significantly improves the recovery of Legionella spp. in low contaminated samples.