Beware of your ready-to-eat foods: They may be resistant to antibiotics

Many people are busy at work and have to rush through their three meals a day, and ready-to-eat foods have become the first choice for most people because of their convenience. So, has the "convenience on the tip of the tongue" been achieved, and has the "safety on the tip of the tongue" also been met?

Ning Xiner/Text

In the fast-paced modern life, we often rush to eat our three meals a day, and a variety of ready-to-eat foods are becoming more and more the first choice for filling our stomachs. Sandwiches, salads, freshly cut watermelons... there are always delicious foods that can be eaten whenever you want. However, are these foods that bring "convenience on the tip of the tongue" safe enough?

Recently, a paper published in the journal Scientific Reports revealed that researchers found a class of genes in all samples of 18 ready-to-eat (RTE) foods randomly purchased from six supermarkets in southern China, including eight ready-to-eat meats, such as barbecued pork, roast duck, roast chicken and salmon sushi; seven ready-to-eat vegetables, such as cucumber, kelp or lotus root; and three ready-to-eat fruits, such as freshly cut cantaloupe. A class of multidrug resistance genes that can make bacteria resistant to multiple antibiotics (scary!). Although further in-depth research is still needed, including research with larger sample sizes, the results reveal potential food risks associated with ready-to-eat foods.

We all know that ready-to-eat food is food that has been cooked in advance and can be eaten directly without further heating or processing. Due to its product characteristics, this type of food is easily invaded by foodborne pathogens due to factors such as cross-contamination. For example, Listeria monocytogenes (LM, hereinafter referred to as "Listeria monocytogenes") is widely present in nature and is a zoonotic pathogen. After infection, the main manifestations are sepsis, meningitis and monocytosis, and it can also cause miscarriage, intrauterine fetal death, and neonatal death. The bacteria do not require high environmental conditions and are one of the main pathogens in ready-to-eat foods that threaten human health. The results of food safety monitoring risks in my country in recent years show that Listeria monocytogenes has the highest contamination rate in raw meat and ready-to-eat foods. Ready-to-eat foods are a gathering place for antibiotic resistance genes and antibiotic-resistant bacteria, which may bring certain risks to consumers.

The study found that the most abundant bacterial communities in the above-mentioned ready-to-eat foods are Proteobacteria (a major phylum of bacteria, including many pathogens, such as Escherichia coli, Salmonella, Vibrio cholerae, Helicobacter pylori and other famous genera), Firmicutes (most of which belong to the class Clostridium, of which the spherical Clostridium subgroup and the soft Clostridium subgroup are the two most common groups in the intestine) and Cyanobacteria (a type of bacteria that can obtain energy through oxygenic photosynthesis, widely distributed, generally grow in fresh water, sea water and soil, and can also grow in extreme environments; different types of cyanobacteria contain different types of toxins). Among them, Proteobacteria have the highest proportion of antibiotic resistance genes. In addition, multidrug resistance genes are the most common antibiotic resistance genes.

The researchers also found that ready-to-eat meats contained the highest number of genes that make bacteria resistant to individual antibiotics - these antibiotics include tetracyclines, sulfonamides, beta-lactams, aminoglycosides, and quinolones, which are commonly used in human or veterinary medicines, indicating that these antibiotics may be overused in the livestock industry.

Escherichia coli

Generally speaking, the more antibiotics are used, the more bacteria begin to adapt. Some bacteria are not completely "eliminated" by antibiotics, but reproduce with the next generation, and "the disciple surpasses the master", the next generation evolves stronger and stronger, more resistant or even "super resistant", even if we have all kinds of skills, it is difficult to deal with it.

It is undeniable that the problem of drug resistance of pathogens has become a global public crisis. The World Health Organization (WHO) listed the abuse of antibiotics and other drugs as one of the top ten global health threats released in January this year. The United Nations has set up a special investigation team on antimicrobial resistance (UNInteragency Coordination Group on Antimicrobial Resistance), which issued a report in April this year warning that if no action is taken, the number of deaths attributed to drug resistance will rise to 10 million per year by 2050. Now the number of deaths due to antimicrobial resistance has reached 700,000 per year (again, it’s terrifying to think about it!).

In general, whether drug-resistant genes are harmful to the human body still requires more systematic research, and subsequent tracking of the contamination pathways of antibiotic-resistant bacteria and antibiotic-resistant genes in food production is necessary.

On the one hand, the ready-to-eat food market is very hot, and more and more consumers tend to buy ready-to-eat food. On the other hand, whether ready-to-eat food can pass the safety test is still questionable. Does choosing convenience also mean having "safety on the tip of the tongue"? This is of course a big question mark. I hope that when you "buy, buy, buy" ready-to-eat food, you will also pay attention to food safety issues.

Compiled from: Scientific Reports, https://nature.com/articles/s41598-020-72620-4