Preliminary Detection and Characterization of Salmonella Enteritidis Isolated from Chicken Nuggets in Türkiye: Evidence of Antimicrobial Resistance and Biofilm Formation

This study presents the preliminary detection and characterization of Salmonella Enteritidis isolated from retail chicken nugget samples in Türkiye. A total of 150 samples were collected from retail markets and analyzed following ISO 6579-1:2017 and ISO 6579-3:2014 standards for isolation and serotyping. S. Enteritidis was recovered from two samples, corresponding to a prevalence of 1.33%, indicating a low but confirmed presence in processed poultry products. Antimicrobial susceptibility testing was performed using the disk diffusion method in accordance with CLSI guidelines. Both isolates exhibited resistance to cefepime and amoxicillin-clavulanic acid, while one isolate was additionally resistant to cefoxitin. No multidrug resistance was observed among the isolates. Biofilm-forming ability was evaluated at 20 °C and 37 °C after 24, 48, and 72 h of incubation using the microtiter plate assay. While weak biofilm formation was observed at early incubation times, both isolates demonstrated strong biofilm production after 72 h at 20 °C, suggesting enhanced persistence under suboptimal temperature conditions relevant to food processing environments. Given the limited number of isolates, the results should be interpreted as preliminary. Nevertheless, these findings provide valuable baseline data on the occurrence, antimicrobial resistance profiles, and biofilm-forming capacity of S. Enteritidis in chicken nuggets in Türkiye, and highlight the need for larger-scale surveillance studies and molecular-level investigations to better assess public health risks.