Prevalence and serotype distribution of Shiga toxin-producing Escherichia coli (STEC) in raw animal and plant food samples from Kocaeli province, Türkiye

Abstract

Shiga toxin-producing Escherichia coli (STEC) is a major foodborne pathogen with significant public health risks. This study comprehensively investigated the prevalence and distribution of seven clinically important STEC serotypes and the O104 serotype, which was assessed in food samples for the first time in Türkiye. A total of 220 raw food samples beef (n = 49), chicken (n = 40), fish (n = 42), leafy greens (n = 44), and raw milk (n = 45) were collected from four regions in Kocaeli, Türkiye, between May and October 2024. Samples were analyzed for stx, eae, and serotype genes using Real-Time PCR (qPCR). Serotyping was performed with multiplex qPCR for O26, O45, O103, O111, O121, O145, and monoplex qPCR for O104 and O157. STEC was detected in 27 samples (12.27 %). Among the 46 isolates, O103 (32.60 %) was the most prevalent, followed by O157 (19.56 %), O45 (17.39 %), O121 (8.69 %), O104 (6.52 %), and others (15.21 %). This study represents the first report of STEC O104 in food samples in Türkiye, emphasizing its public health significance and the necessity for enhanced food safety surveillance. STEC prevalence was highest in beef (32.65 %), followed by raw milk (13.33 %), chicken (7.50 %), fish (2.38 %), and leafy greens (2.27 %). The most frequently detected serotypes in beef were O103 and O157, while O45 was dominant in chicken. O157 was the only serotype found in fish, whereas O103 was identified in leafy greens. Multiple serotypes, including O103, O111, and O157, were detected in raw milk. These findings underscore the need for sustained monitoring and control strategies to mitigate STEC-related risks.