Identification and molecular characterization of pathogenic bacteria in foods confiscated from non-EU flights passengers at one Spanish airport

Two hundred food samples of animal origin confiscated from passengers arriving on flights from non-European countries at the International Airport of Bilbao (Spain) were tested for the presence of four main bacterial foodborne pathogens (Campylobacter spp., Escherichia coli 0157:H7, Listeria monocytogenes and Salmonella spp.) during 2012 and 2013. Overall, 20 samples were positive for L. monocytogenes (10%) and 11 for Salmonella spp. (5.5%), whereas Campylobacter spp. and E. coli 0157:H7 were not detected in any sample. The positive isolates were widely clustered: 14 and 7 different pulsotypes for L monocytogenes. and Salmonella spp. isolates, respectively. Nine sequence types (ST) were detected for L monocytogenes: ST2 (45%), 519 (15% isolates), ST8 and ST87 (10%), and ST308, 5T37, ST155 and 5T378 (5%). The Salmonella spp. isolates belonged to seven serovars: monophasic serovar 4,12;d:- (3; 27.3%), Rauform (2; 18.2%), Anatum (2; 18.2%), Oranienburg, Enteritidis, Newport and Typhimurium (1; 9.1% each). Antibiotic resistance among L. monocytogenes isolates was high, especially for clindamycin and daptomycin (more than 95% of the isolates). These results indicate that food samples imported by travelers in their personal luggage may harbor the most prevalent L. monocytogenes genotypes and Salmonella spp. serovars responsible for foodborne outbreaks worldwide. Consequently, international travel can play an important role in the prevalence and dissemination of successful clones of foodborne pathogenic bacteria, and continuous monitoring of international movements is of importance to better understand clonal evolution and emergence and dissemination of successful lineages.