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- Find a treasure trove: a drug-resistant mutant strain of tuberculosis has entered the Russian Federation
Find a treasure trove: a drug-resistant mutant strain of tuberculosis has entered the Russian Federation
The dangerous pathogen of tuberculosis EurA1.1 has begun to circulate in Russia, a genetic study by European scientists has shown. According to their data, this variant of mycobacterium is most common in Belarus, as well as in the EU. The transmission of the pathogen within the Russian Federation was also confirmed by domestic doctors. According to them, due to the resistance of the pathogen to several types of antibiotics, the treatment of infection is complicated. However, doctors still have the means to combat the disease. Clinical trials of a modern tuberculosis vaccine, which is expected to provide protection against EurA1.1, have been completed in our country.
Drug-resistant tuberculosis in the Russian Federation
A group of Irish scientists from Dublin conducted a genetic study of a strain of mycobacteria called EurA1.1. According to their data, this branch of the causative agent of tuberculosis is most common in Belarus, but it is also found in other European countries, including Russia. The researchers analyzed the genomes of 1,362 samples, 62 of which were obtained in our country. The data for analysis was taken from open international genetic databases.
The peculiarity of the representatives of this clade is their resistance to several antibiotics, which are commonly used to treat tuberculosis.
"Analysis of the genomic variants revealed widespread resistance to key first- and second-line antibiotics, as well as the emergence of resistance to new therapeutics such as bedaquiline and linezolid, which are currently used to treat multidrug-resistant tuberculosis. Evolutionary analysis also revealed cross-border genomic characteristics of relatedness between isolates EurA1.1 collected outside of Belarus, and samples from other Eurasian countries, including Germany, Ukraine, Moldova, Russia and Georgia," — said the authors of the article in a scientific journal npj Antimicrobials and Resistance.
EurA1.1 was first discovered in 2006 during a study of a collection of clinical isolates isolated on the territory of Belarus. In addition to the main outbreak in this country, the hoard was also identified in the north-west of Russia — in the Pskov and Novgorod regions, as well as in Karelia, said Anna Panova, head of the Scientific Department of Microbiology and Molecular Genetics at the National Research Medical Center for Phthisiopulmonology and Infectious Diseases of the Russian Ministry of Health.
— Strain EurA1.1 is not dominant among other Mycobacterium genovariants. Its detection is primarily related to the expansion of diagnostic capabilities of laboratories and the introduction of genetic technologies," the specialist said.
According to her, the main danger of EurA1.1 is determined not by biological aggressiveness, but by a combination of resistance to key drugs. However, this does not mean that the infection is incurable. For such pathogens, it is crucial to individually determine drug sensitivity. In some cases, a personalized treatment regimen based on the results of phenotypic and molecular testing is required.
Albert Rizvanov, head of the Personalized Medicine Excellence Center at Kazan Federal University, explained to Izvestia that EurA1.1 is not considered a new pathogen that has just appeared in Russia. Similar variants of this genetic line have been identified in our country before. At the same time, based on the results of the study, it is impossible to determine what proportion of all tuberculosis cases in Russia today is associated with EurA1.1, since scientists analyzed the already available genomic data, rather than conducting a complete survey of the population.
— It is currently impossible to predict how widely this option will spread across Russia. It is transmitted in the same way as ordinary tuberculosis, mainly through the air during prolonged contact with a patient with an active form of the disease. The very fact of antibiotic resistance does not automatically make the bacterium more contagious. The problem is different: a person can become infected with an already resistant bacterium, and then the standard treatment will work worse from the very beginning," the expert said.
Treatment and vaccination against infection
The danger of EurA1.1 is primarily related to the fact that such an infection is much more difficult to treat, Albert Rizvanov noted. Many of the studied samples showed resistance to several major anti-tuberculosis drugs at once. This is part of a broader global problem: bacteria are gradually accumulating antibiotic resistance, and microorganisms are emerging that are less effective against conventional drugs.
At the same time, no specific symptoms specific to EurA1.1 have been identified. It is impossible to determine from the external manifestations whether the pathogen is sensitive to drugs or resistant — laboratory tests are necessary for this.
— The study really shows a very high resistance to a number of long—used drugs, and in some samples, to some modern drugs. But resistance, for example, to bedaquiline and linezolid was not found in all bacteria of this lineage, and for some other new drugs, no genetic signs of resistance were found at all," Albert Rizvanov added.
Such tuberculosis remains curable, but treatment becomes more difficult and requires an individual selection of a combination of drugs based on the results of a drug sensitivity test, the specialist emphasized.
In these conditions, vaccines, rather than antibiotics, are becoming one of the most effective means of combating tuberculosis. The standard BCG vaccine contains live weakened mycobacteria. However, even after vaccination, a person may get sick in some cases. Therefore, the Gamalea Center has created a drug designed to strengthen the already formed protection. The third phase of clinical development studies has been completed. The drug should also protect against the resistant strain EurA1.1, Alexander Gintsburg, the scientific director of the organization, told Izvestia.
— The trials are over. An array of clinical data is currently being processed, which has been obtained over three years. Several dozen clinical centers participated in the study. The presence of antibiotic resistance in a particular clade does not affect the effectiveness of protection against it. It depends on the antigenic composition of the vaccine strain," he said.
Theoretically, the vaccine can not only protect against infection, but also have a positive effect on an already infected person if the disease is not acute. However, separate studies are needed to test this hypothesis, the scientist emphasized.
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