Study of Arcobacter spp. contamination in fresh lettuces detected by different cultural and molecular methods

Arcobacters are considered potential emerging food and waterborne pathogens. However, there is no data on the presence of Arcobacter spp. in fresh vegetables. Therefore the objective of this research was to study the presence of Arcobacter spp. in fresh lettuces. Fifty fresh lettuces purchased from different local shops in Valencia (Spain) were analyzed. The assay was performed simultaneously by cultural and molecular methods. Isolates were identified by real-time, multiplex PCR and restriction fragment length polymorphism analysis of PCR-amplified DNA fragment (PCR-RFLP). Finally, all the isolates were genotyped using the randomly amplified polymorphic DNA (RAPD-PCR) method. Arcobacter sp. was detected in 10 of the 50 samples (20%) by real-time PCR, being A. butzleri the unique detected species by mPCR. The detection levels obtained by conventional PCR (7 samples/50, 14%) were slightly lower. These seven samples were found to be positive also by culture isolation. All 19 obtained isolates were identified as A. butzleri by multiplex PCR and PCR-RFLP. Great genetic heterogeneity among the isolates was observed by RAPD-PCR profiling. To our knowledge, this is the first study in which Arcobacter spp. is detected in fresh vegetables such as lettuces. Although these foods are generally considered safe, given the large quantities consumed and the fact that further cooking is absent, lettuce could be a source of Arcobacters of public health concern. (C) 2010 Elsevier B.V. All rights reserved.