Getting on biofilm: a "sketch" of dangerous bacteria will protect cattle from resistant infections

Scientists have identified the genetic and phenotypic, i.e. external, features of bacteria related to their ability to form antibiotic-resistant communities in the body of farm animals. They found that microorganisms with certain genes and a high ability to form biofilms are significantly less susceptible to the action of drugs. The data obtained will help to more accurately identify potentially dangerous strains and develop new approaches to combating resistant infections that cause significant damage to livestock. Experts also told Izvestia that this would make food safer, as it would be possible to monitor and evaluate the viability of bacteria throughout the food chain.

Features of antibiotic-resistant bacteria

Scientists from Omsk State Agrarian University named after P.A. Stolypin (Omsk) and the Ural Federal Agrarian Research Center of the Ural Branch of the Russian Academy of Sciences (Yekaterinburg) have found out which marker genes and properties of the bacteria themselves determine the formation of resistant biofilms in pathogens infecting cattle and pigs.

Veterinary specialists often use antibiotics to treat farm animals. Uncontrolled use of such drugs leads to the fact that bacteria lose their sensitivity to them. Moreover, many bacteria are able to combine into complex communities — biofilms, in which they are covered with protective mucus. They often form on the surfaces of milking machines, drinkers and other equipment, and this leads to a constant spread of infections among farm animals, the scientists said.

Until now, it was not fully understood which genetic mechanisms underlie the formation of antibiotic-insensitive bacterial communities and to what extent the thickness and strength of biofilms are associated with drug resistance.

The authors studied E. coli and staphylococcus bacteria, widespread species that cause inflammation of the mammary glands and intestines in farm animals, as well as other diseases. The specialists collected samples of microorganisms from the mucous membranes of cattle and pigs, as well as from the surfaces of technological equipment in livestock farms.

First of all, the scientists assessed how quickly bacteria form biofilms while in a nutrient medium, and also investigated the properties — thickness and strength — of the communities being formed. In addition, the authors conducted a molecular genetic analysis of key genes associated with the formation of an extracellular matrix, a "framework" for building biofilms. In parallel, they tested the sensitivity of microorganisms to four popular antibiotics. This allowed us to determine which genes determine the ability of bacteria to actively form communities and thereby lose sensitivity to antibacterial drugs.

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Experiments have shown that bacteria with certain genes that form denser and more durable biofilms had increased resistance to the action of antibacterial drugs. For example, staphylococci, which form thick and durable clusters, turned out to be 37-53% less sensitive to all antimicrobial agents tested.

— The data obtained will be useful for employees of veterinary services and agricultural enterprises, as they will allow us to develop effective strategies for controlling infections that cannot be treated with existing antibiotics. Such control will help reduce the risk of the spread of resistant bacteria among animals and humans and increase the safety of animal products, effectively develop agriculture," said Igor Antonevsky, Candidate of Veterinary Sciences, Assistant Professor at the Department of Veterinary Microbiology, Infectious and Invasive Diseases, Faculty of Veterinary Medicine, Omsk State Agrarian University.

In the future, experts plan to expand research in the field of developing new approaches to the diagnosis and prevention of infections in animal husbandry associated with biofilm formation.

How are biofilms dangerous for livestock

Resistant strains of staphylococcus and E. coli pose a significant threat to livestock, said NTI expert on crop production and animal husbandry Yulia Barankina. They are more likely to lead to chronic or recurring infections, last longer in the herd, and are more likely to require a change of therapy or more aggressive measures. This increases losses in dairy and meat productivity, increases treatment costs, and increases the risk of transmission of resistant bacteria along the animal–human chain through direct contact or food.

"The specific degree of risk depends on various factors: the conditions of detention, the level of hygiene, the frequency and range of antibiotic use, as well as the availability of monitoring and control programs in the farm," she said.

According to her, the study indicates areas for the development of new infection control strategies: rapid strain identification tests, drugs that destroy the extracellular matrix, compounds that improve the penetration of antibiotics into biofilms, and the development of other preventive measures.

Infections that are difficult to treat are traditionally detected in animal husbandry, including the ineffectiveness of antibacterial therapy, which is due to a number of factors, presumably the formation of biofilms, the head of the Smart Supply Chain segment of the FoodNet working group told Izvestia NTI Sergey Kosogor.

— There are very few studies of bacterial biofilms associated with livestock. A deep understanding of their possible role in diseases and drug resistance can help in the prevention and treatment of diseases in cattle," he stressed.

The expert noted that the results of the study can contribute to the development of new treatment methods, preserve animal productivity and reduce the negative impact of diseases in the development of which bacterial biofilms play an important role, in particular mastitis and respiratory diseases of cattle.

From an economic point of view, this will help to strengthen food security, as well as improve the quality and safety of food products. In addition, new approaches will make it possible to more effectively monitor and evaluate the viability of bacteria at all stages of the food chain, which will reduce risks to consumer health.

The results of the study, supported by a grant from the Russian Science Foundation, are published in the journal Agrarian Bulletin of the Urals.​