Researchers from Julius Kühn Institut, Germany found that a supermarket salad can transfer antibiotic resistance genes, which are difficult to detect.
The research team analysed supermarket salad, arugula, and cilantro purchased from supermarkets in Germany. The study is titled ”The Transferable Resistome of Produce”. The authors found that: “Leafy greens can be a reservoir of transferable antibiotic resistance genes.”
To contextualise the study, the authors point out that there have been several foodborne disease outbreaks associated with produce contamination globally. They also note that antibiotic resistance in bacterial pathogens has increased worldwide due to the “widespread use and misuse of antibiotics.”
Antibiotic resistance makes it possible for bacterial infections such as E-coli to cause sepsis which can lead to death. According to the World Health Organization, sepsis kills 6 million people every year.
How can a supermarket salad transfer genes?
The study identifies that the microbome of produce is important for plant health but can also contain potentially pathogenic bacteria from human and animal sources, including Escherichia coli strains. The contamination of produce with potentially pathogenic bacteria from human and animal sources can occur preharvest or postharvest.
Examples of preharvest contamination include:
- From wild animals;
- Irrigation water;and
- Organic fertilisers.
Detecting antibiotic resistance genes
The produce was analysed by means of cultivation- and DNA-based methods. The study found that these transferable antibiotic resistance genes often escape traditional molecular detection methods.
The findings show that supermarket salad and other produce may transfer antibiotic resistance genes and yet remain indetectable using cultivation-independent DNA-based methods.
The study said: “This study highlights the importance of the rare microbiome associated with produce as a source of antibiotic resistance genes that might escape cultivation-independent detection, yet may be transferred to human pathogens or commensals.”
The results of the study are in line with high resistance levels to the antibiotics penicillin and trimethoprim.