Scientists reveal genes that exacerbated the cholera epidemic in Yemen

A group of scientists has answered a question - a mystery that healthcare professionals have been searching for a solution to since 2018 - about why cholera patients in Yemen are not responding to antibiotics, especially with indications that genes capable of resistance to the drugs have emerged.

The study, which involved scientists from the Wellcome Sanger Institute, the University of Toronto, the Pasteur Institute and Sana'a University, and was published in the journal Nature Microbiology, revealed the source of antibiotic resistance that has emerged in the bacteria driving the cholera outbreak currently affecting Yemen.

Scientists have found that there is a fifth type of cholera that contains genetic elements capable of resisting drugs, including antibiotics, and it is the main factor in the disease during its outbreak in Yemen.

While the source of the outbreak in Yemen remains unclear, it has certainly been endemic in the country since 2016, the largest cholera outbreak in modern history. Antibiotic resistance began to emerge in cholera patients in 2018, which scientists say has exacerbated the crisis significantly.

Danger gene

After the study team analyzed 260 DNA samples of cholera bacteria collected in Yemen between 2016 and 2019, it was found that the cause was due to the widespread use of azithromycin and other macrolide antibiotics at that time.

The study noted that pregnant women and children in Yemen with cholera were treated with erythromycin and azithromycin from 2016 until late 2018, at which point there was a sudden change in the antimicrobial susceptibility profile.

The researchers said that these strains, which are considered immune to drugs, were not transferred outside Yemen, and their emergence is linked to the long-term contact of their ancestors with macrolide antibiotics, which led to the emergence of less infectious types of bacteria, but they carry genes resistant to antibiotics.

In their study, the researchers genotyped cholera samples taken from Yemen, 84% of which contained the T13 subgenome, a strain that carried a distinctive plasmid that was shown to be the cause of cholera drug resistance.

A plasmid is a small circular piece of DNA, found mainly in bacteria and some other organisms such as some yeasts. A plasmid is characterized by its ability to replicate itself independently of the chromosome that carries the main bacterial DNA. It often contains genes that give cells certain properties, such as resistance to antibiotics or the ability to produce certain proteins.

How is resistance done?

Immunology and stem cell expert, Dr. Adeeb Al-Zoubi, believes that the results of this study are intuitive, and it is scientifically known that the use of different antibiotic drugs may put pressure on bacteria to resist the drugs, so the bacteria change their genes to prevent the effectiveness of the antibiotic on them.

Al-Zoubi said, in his interview with Al Jazeera Net, that this process leads to the birth of genetically different strains that resist these antibiotics, by causing genetic mutations that change the genes of these bacteria so that they produce effective proteins to resist the action of the antibiotic.

Incorrect use of antibiotics in patients plays a major role in causing these dangerous mutations that allow bacteria to resist the antibiotic, he said.

"In this way, different ineffective antibiotics are used by many patients, which leads to partial killing of bacteria, while other bacteria develop themselves to resist this ineffective antibiotic," he added.

This in turn causes the creation of several strains of these bacteria that are resistant to different antibiotics. In most cases, one person may be infected with more than one strain, and the strains merge with each other inside the patient's body, leading to the creation of bacteria that are resistant to several types of antibiotics at the same time, according to his statement.

With signs of drug-resistant genes emerging, and cholera spreading rapidly in areas lacking clean water and proper sanitation, and can be fatal if not treated promptly, strengthening health, nutrition, water, sanitation and hygiene services is critical to addressing the root causes of the situation.

Source: Al Jazeera