Abstract
Vegetables are one of the main foodstuffs consumed in the Mediterranean diet. However, raw vegetables have been associated with relevant foodborne outbreaks worldwide. Accurate knowledge of the microbiological quantitative risks associated with these matrices is crucial in order to define effective control measures, avoiding the survival and dissemination of foodborne pathogens through the different food chain stages. The aim of the present study is the assessment of the prevalence of Helicobacter pylori (a unique carcinogenic biological agent recognized to date) on leafy vegetables (spinach, lettuce, and chard) by means of the detection of the specific pathogenicity vacA gene. A real-time quantitative polymerase chain reaction (qPCR) optimized approach was used to detect H. pylori-positive samples and the concentration of this pathogen (with a limit of detection equal to 10 cells). One hundred raw vegetable samples were acquired in markets corresponding to the Spanish Mediterranean area. Sliced vegetable leaves were homogenized and centrifuged, and DNA was extracted from the homogenates. qPCR results confirmed 20 out of 100 H. pylori-positive samples, with melting temperature (Tm) values in the range of 84.8–86.5 °C (TmvacA H. pylori = 85 °C). Amplicons were cut, purified, and sequenced to confirm the homology with the H. pylori vacA gene. A total of 17 out of 100 vegetable samples (12/45 (26.6%) lettuce, 2/21 (9.5%) spinach, and 3/34 (8.8%) chard samples) were finally confirmed as H. pylori-positive. Contamination levels were in the range of 1.5 ± 0.3 to 2.5 ± 0.1 log10 cycles (36–335 CFU/g leafy vegetables). Our results show that H. pylori is detected by qPCR at levels close to infectious doses in fresh vegetables, thus posing a food safety hazard.
Highlights
Current trends in adopting healthy lifestyles are leading to an increase in the demand for and consumption of fresh green-leafy vegetables [1]
Beyond the gastrointestinal infections and outbreaks associated with main pathogens, such as Escherichia coli, Salmonella spp., or Listeria monocytogenes, Blau et al (2018) remark upon the capability of these bacteria to transfer resistomes, which can interact with human microbiota, with possible fatal consequences in terms of antibiotic resistance dissemination and microbiota dysbiosis [2,3]
Three factors have been considered as critical in the risk associated with these bacteria: (i) the concerning consequences associated with H. pylori chronic infection, as 6.2% of gastric cancers derived from infections are attributable to H. pylori; (ii) the antibiotic resistance of this pathogen to existing therapies, which led the World Health Organization to include H. pylori in February 2017, for the first time, in the list of the most antibiotic-resistant pathogens, with it being a high priority to search for alternative treatments [6–8]; and (iii) the high capability of Helicobacter spp. to disseminate in the environment
Summary
Current trends in adopting healthy lifestyles are leading to an increase in the demand for and consumption of fresh green-leafy vegetables [1]. This has public health consequences derived from the microbial contamination of this type of product. Three factors have been considered as critical in the risk associated with these bacteria: (i) the concerning consequences associated with H. pylori chronic infection (e.g., stomach cancer and gastric mucosa-associated lymphoid tissue lymphoma, MALT), as 6.2% of gastric cancers derived from infections are attributable to H. pylori; (ii) the antibiotic resistance of this pathogen to existing therapies (rate of treatment efficacy
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
