Validation of direct plating of a stool sample as a method for Listeria monocytogenes detection

The aim of current studies was to validate the direct plating of a stool sample for Listeria monocytogenes detection, using selective medium Palcam agar with Palcam selective supplement. Validation was performed using stool samples collected from healthy humans inoculated with Listeria sp. strains. Stool samples were frozen to determine the influence of freezing on method robustness. The presented research defines the Listeria monocytogenes limit of detection (LOD) as 103 cfu/g of stools for fresh and frozen samples. Repeatability and reproducibility of the method has been confirmed using statistical methods. We show the effectiveness of direct plating of stool samples on Palcam agar with Palcam selective supplement collected for Listeria monocytogenes detection. This method could be useful for this pathogen detection in stool samples collected from patients with diarrhoea.