Agar Macconkey suplementado con cefotaxima: su utilidad para la vigilancia de colonización por Enterobacterales productores de BLEE: ensayo piloto

Objectives: To determine the sensitivity and specificity of MacConkey agar supplemented with cefotaxime (ESBL agar) compared to conventional methods for the detection of ESBL-producing Enterobacteriaceae in fecal samples from children aged 0–12 years at the Mórrope Health Center in Lambayeque, Peru, in 2025. Materials and methods: This was an observational, cross-sectional, descriptive study conducted in a population of 155 children under 12 years of age. Stool cultures were divided into two study phases. During the first phase (60 samples), bacterial isolation was performed on conventional media: MacConkey agar without supplementation, SS, and XLD. During the second phase (95 samples), bacterial isolation was performed on conventional media and also on MacConkey agar supplemented with 30 mg/L cefotaxime (ESBL agar). Furthermore, phenotypic confirmation of the resistance mechanism was performed using the double diffusion method. Results: In the first phase (60 samples), conventional culture did not recover ESBL-producing bacteria. In the second phase, out of 95 samples, ESBL agar presented 69.4% of suspected isolates, with phenotypic confirmation in 93.9% of cases, obtaining 65.2% as the final prevalence of ESBL in the studied population. Furthermore, the supplemented medium presented a sensitivity of 100 % with a specificity of 87.9% in the detection of ESBL. Conclusions: This medium has the potential to be incorporated into protocols to shorten the time of suspicion and identification of multidrug-resistant microorganisms in clinical samples such as urine or respiratory secretions, improving screening from the primary plate.