Preliminary study found an organic vegetable company

New research to be presented at the European Conference on Clinical Microbiology and Infectious Diseases (ECCMID) in Lisbon, Portugal (23-26 April) (23-26 April), suggests that pathogenic amoebas that live on organic leafy vegetables can protect human pathogens. Like pseudomonas, salmonella, And Helicobacter It poses a potential threat to public health. The study was led by Dr. Yolanda Moreno and colleagues from the Universidad Politecnica de Valencia in Spain.

Foodborne illness from eating contaminated fresh produce is common and can have serious effects on human health, especially when eaten raw. There is a growing demand for organically grown fruits and vegetables as people seek healthy meals amid concerns about potential contamination from pesticides, chemical fertilizers and herbicides. However, during growth, harvesting, transportation and further processing and handling, fresh produce can be contaminated with pathogens from human or animal sources, through contact with soil, irrigation water, air, rain, insects, and during industrial product washing.

Vegetables can be contaminated with some protozoa (single-celled organisms) such as free-living amoebae (FLA), which feed on bacteria and can act as a host for pathogenic bacteria (so-called “Trojans”) that resist FLA digestion and can pose a threat to health the public.

“Food and food-related environments create an ideal meeting place for amoebas and disease-causing bacteria,” Dr. Moreno explains. “However, relatively little is known about the occurrence and diversity of free-living amoebas on organic vegetables and their role in the transmission of human pathogens.”

To perform a preliminary study of the FLA microbiome isolated from organic vegetables, researchers collected 17 samples of lettuce and spinach from local supermarkets in Valencia between November 2020 and May 2021.

To check the degree of contamination, the researchers used a metagenomic technique that identifies the DNA in all the bacteria contained within the FLA. The results were evaluated to determine the types of microbiomes present in each sample.

The main bacterial species identified are Flavobacterium (found in 10% of vegetable samples) and Pseudomonas (10%), many of which do not cause disease in humans. However, a third of the samples (34%) contained 52 types of potentially pathogenic bacteria including LegionellaAnd salmonellaAnd Arcobacter. The resulting infection can cause illnesses – including pneumonia and gastrointestinal disease.

Moreover, the types of FLA Vermopa worms which usually cause severe infections in humans were found in one-fifth (19%) of vegetable samples; And Acanthamoeba castellaniiwhich can cause blindness and encephalitis in nearly two-thirds (63%) of samples.

“The presence of bacteria of public health concern within the free-living amoebae suggests that they are compounds that can easily transmit pathogens capable of reaching humans and causing health problems through contaminated organic vegetables,” says Dr. Moreno. Pollution can arise as a result of soil treatment with organic fertilizers such as manure and sewage sludge and from irrigation water. Leafy greens are particularly susceptible to fecal contamination due to their proximity to the ground and the potential for humans to consume them without cooking. Our findings also emphasize the need to educate the public about the safe and proper handling of fresh organic vegetables before eating them fresh or lightly cooked.”

Despite the important findings, the authors note that the study included only a small sample of leafy organic vegetables from one city in Spain, and larger studies from different countries are needed to understand more about the microbiological quality and safety of organic vegetables.

For interviews with the authors of the report, please email Dr. Yolanda Moreno, Universidad Politecnica de Valencia, Spain at

Alternate contact in the ECCMID Press Room: Tony Kirby T) + 44 (0) 7834 385827 E)

Notes to editors:

This research was supported by Cynthia’s Spanish Minister, Innovación y Universidades.

The authors declared that there was no difference in interests.

This press release is based on the 191st poster presentation at the European Conference on Clinical Microbiology and Infectious Diseases (ECCMID). All widely accepted abstracts were reviewed by the conference selection committee. There is no complete research paper at this point, but the authors are happy to answer your questions. The research has been submitted to a medical journal for publication.

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