Bacteria discovered can mutate and become resistant to antibiotics

Bacteria are often linked to disease, but they can also be beneficial to humans. Present in the human microbiota, whether in the skin, mouth, intestine, they are fundamental for body homeostasis, that is, the constant balance of biological functions.

“We must think that practically everything is colonized by microorganisms. In humans and other animals, colonization by bacteria and other microorganisms begins at birth,” says Professor Nilton Lincopan, from the Department of Microbiology at the Institute of Biomedical Sciences at USP.

genes
A study published in the scientific journal Proceedings of the National Academy of Sciences comments that a gene, probably coming from bacteria, is present in the vision of vertebrates, including humans. The professor points out that the transfer of genes between bacteria and humans is a controversial and not conclusive issue, however, addressing only the bacterial portion, this becomes much more realistic.

“Horizontal gene transfer normally occurs from bacteria to bacteria (also with the Archaea domain ), but it can also occur between bacteria that serve as donors and organisms such as fungi and plants that act as recipients, always considering the sharing of a common niche ”, explains Lincopan.

Impacts
Even if the study does not confirm the passage of the gene to humans, it puts horizontal gene transfer as one of the possible means. This activity normally occurs among prokaryotes, that is, they do not have a nuclear envelope, and can be pressured by environmental factors.

“It is a genetic event that normally occurs among bacteria defined as prokaryotes. In this scenario, the protagonists are donors and recipients and the participating elements are genes, plasmids, bacteriophages and other systems that are part of the so-called bacterial mobiloma [molecules with genetic material that can move from the cells of one organism to another, inserting themselves in the his genome]. It is implied that horizontal gene transfer can be beneficial to one recipient, but depending on which gene is transferred, it can be harmful to a third individual.” He adds: “The transfer can be triggered by physical-chemical conditions of the environment or stress situations such as, for example, the selective pressure caused by the use of an antimicrobial. So in this case,

antibiotics
It is known that, to treat pathogenic bacteria, the use of antibiotics is very common. However, in certain cases, it can affect our microbiota. “It can affect the microbiota that protects us. Think of the following situation: if a patient receives a broad-spectrum antibiotic treatment to treat an infection, wouldn’t it also destroy the microbiota itself? Imagine that there are many chairs in the intestine, but all the chairs are occupied by beneficial bacteria; if I use the antibiotic, I end up killing all the bacteria that are sitting there. Therefore, the chairs are empty and susceptible to any bacteria”, puts Lincopan.

One example, according to the professor, are the antibiotics used in broiler chickens: “We can think of a real situation: what would an ecosystem related to agribusiness be like, in which they use an antibiotic mixed in the feed as a promoter of broiler chicken growth? The antibiotic could exert a selective pressure on the animal’s microbiota, which is formed by species of bacteria sensitive to the antibiotic and resistant species, with a gene that would allow survival. What would happen if, by horizontal gene transfer, a resistant, donor bacterium transferred a resistance gene to a sensitive, recipient bacterium through conjugation? We are going to have new resistant species”.

Likewise, the human intestinal microbiota could suffer a genetic alteration, through horizontal gene transfer, and give rise to new resistant species: “This bacterium could be a donor of the resistance gene for a sensitive species that is part of the microbiota of the human being. In this example, the anthropogenic use of an antibiotic to create an animal contributed to the establishment of horizontal gene transfer, but also favored the appearance of a resistant species that could infect an individual without further possibility of treatment”, points out Lincopan.