Unusual Detection of Kurthia sp. Strain CMMC05 on ALOA Medium Leading to False‐Positive Listeria Identification in Chicken Meat

A bacterium was isolated during routine detection of Listeria spp. from chicken meat using Agar Listeria according to Ottaviani and Agosti (ALOA). The isolate produced bluish‐green colonies on ALOA. This color indicates β‐D‐glucosidase activity, a feature commonly used to presumptively identify Listeria spp. However, later biochemical and molecular analysis revealed discrepancies compared with the reference strain Listeria monocytogenes ScottA. PCR analysis showed the absence of major virulence‐associated internalin genes ( inlA, inlB, and inlC ). To confirm the taxonomic identity, 16S rRNA gene sequencing was performed. BLASTn analysis against the NCBI database identified the isolate as belonging to the genus Kurthia , with the highest sequence similarity to Kurthia gibsonii NBRC 15534 T . GC–MS fatty acid methyl ester analysis also revealed anteiso‐C15:0 as the main fatty acid, matching Kurthia species. These results revealed that Kurthia sp. strain CMMC05 can grow on ALOA medium and resembles Listeria spp. Such results lead to false‐positive identification. The study highlights a limitation of chromogenic media used in food safety testing and emphasizes the need for molecular identification to avoid misinterpretation of Listeria contamination in poultry products.