Aims:  This study was designed to isolate Shigella spp. strains from food and stool samples by a combination of PCR and culture methods and characterize their serotypes, antibiotic resistance profiles, virulence genes and pulsed‐field gel electrophoresis (PFGE) patterns to investigate possible clonal relationships amongst strains circulating. Methods and Results:  Six Shigella spp. strains were isolated from 280 food samples against 16 Shigella isolates from 236 stool samples of symptomatic patients and asymptomatic food handlers during the period from January 2007 to December 2009 in Public Health Regional Laboratory of Nabeul. The detection of ipaH, ipaBCD, ial, ShET‐1 and ShET‐2 was performed by a PCR technique with specific primers. Conclusions:  The use of PCR technique improved the rate of detecting Shigella in stool samples from 6·7 to 14% and in food samples from 2·1 to 8·6%. Percentage of Shigella isolates and ipaH‐specific PCR demonstrated a marked pattern of seasonality, increasing in summer and fall seasons for human and food isolates. Amongst the environmental strains, 50% of isolates were invasive. However, for the 16 clinical strains isolated, nine were found to be positive for both ial and ipaBCD gene and 11 were found to produce ShET‐1 and/or ShET‐2. XbaI PFGE analysis revealed the presence of a predominant clone amongst Shigella sonnei strains recovered from different sources circulating in Nabeul, Tunisia, throughout the years 2007–2009. Significance and Impact of the Study:  This study demonstrated the existence of Shigella in food samples and dispersion of different virulence genes amongst these isolates, which appear to constitute an environmental source of epidemic spread. The clonal relationships amongst strains isolated from food elements and human stools indicate the incrimination of different kinds of foods as vehicle of transmission of Shigella, which are usually escaped from detection by traditional culture methods.

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A rapid, sensitive, and highly reproducible real-time PCR assay was developed to detect the three major Vibrio spp. pathogenic for humans in Tunisian seafood products and sediments. A conventional culture method found 102 (41.3%) of 247 analyzed samples positive for Vibrio spp.; a conventional PCR method found 126 (51%) of the 247 samples positive. Real-time PCR assay found 126 (51.1%) samples positive; V. alginolyticus toxR was the most common, found in 99 (78.57%) of samples, followed by V. parahaemolyticus in 26 (20.63%) and V. cholerae in 1 (0.7%). All culture-positive samples were PCR positive. However, 24 samples that were positive by conventional PCR and real-time PCR were culture negative. Our findings indicate that retail seafood is commonly contaminated with Vibrio spp. and presents a potential risk to human health in Tunisia. These data also indicate that real-time PCR can provide sensitive species-specific detection of Vibrio spp. in seafood without prior isolation and characterization of the bacteria by traditional microbiological methods.