Ancient murderers are rapidly becoming resistant to antibiotics, scientists warn

Salmonella typhus. (Credit: Microbewriter / Wikimedia Commons / CC BY SA 4.0)

Translated by Julio Batista
Original by Carly Cassella of Science Alert

Typhoid fever may be rare in developed countries, but this ancient threat, believed to have existed for thousands of years, remains dangerous in the modern world.

New studies show that the bacteria that cause typhoid fever develop a wide range of drug resistance and rapidly replace non-resistant strains.

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Currently, antibiotics are the only way to effectively treat typhoid fever caused by bacteria. Salmonella serotype Typhoid fever (S typhoid fever). However, over the last three decades, bacterial resistance to oral antibiotics has increased and spread.

By sequencing the genomes of the 3,489 S typhoid strains contracted between 2014 and 2019 in Nepal, Bangladesh, Pakistan, and India, researchers show a recent increase in drug-resistant (XDR) typhoid fever. discovered.

XDR Typhi is not only resistant to front-line antibiotics such as ampicillin, chloramphenicol and trimethoprim / sulfamethoxazole, but also to new antibiotics such as fluoroquinolones and 3rd generation cephalosporins. there is.

To make matters worse, these strains are rapidly spreading worldwide.

Most cases of XDR typhoid fever occur in South Asia, but researchers have identified nearly 200 cases of international spread since 1990.

Most strains are exported to Southeast Asia, East Africa and South Africa, but typhoid superbugs have also been found in the United Kingdom, the United States and Canada.

“In recent years, the emergence and rate of spread of highly resistant strains of typhoid fever is a real source of concern, highlighting the urgent need for urgent expansion of precautionary measures, especially in the highest-risk countries.” The illness expert said. Infectious disease Jason Andrews of Stanford University.

Scientists have been warning about drug-resistant typhoid fever for years, but the new study is the largest analysis of the bacterial genome to date.

In 2016, the first strain of XDR typhoid fever was identified in Pakistan. In 2019, it became the country’s dominant genotype.

Historically, most strains of XDR typhoid have fought third-generation antibiotics such as quinolones, cephalosporins, and macrolides.

However, in the early 2000s, mutations that conferred resistance to quinolones accounted for more than 85% of all cases in Bangladesh, India, Pakistan, Nepal and Singapore. At the same time, resistance to cephalosporins was well established.

The only remaining oral antibiotics today are macrolides and azithromycin. And this medicine may not work for much longer.

A new study found that mutations that confer resistance to azithromycin are also widespread, “threatening the efficacy of all oral antibiotics for the treatment of typhoid fever.” These mutations have not yet been adopted in STyphiXDR, but if they are, we are facing serious problems.

If left untreated, up to 20% of cases of typhoid fever can be fatal, and today 11 million cases of typhoid fever occur annually.

Typhoid-conjugated vaccines can be used to avoid future outbreaks to some extent, but if access to these vaccines is not expanded globally, the world could soon face another health crisis. I have.

“The recent emergence of azithromycin-resistant XDR and STyphi has increased the urgency of rapidly expanding precautionary measures, including the use of typhoid-conjugated vaccines in typhoid-endemic countries,” the author writes.

“Countries with currently high prevalence of antimicrobial resistance in typhoid isolates require such measures, but should not be limited to these settings given their tendency to become more prevalent internationally. . “

South Asia is the main hub of typhoid fever, accounting for 70% of all cases, but if COVID-19 could tell us something, a variant of this disease in the modern globalized world. Spreads easily.

To prevent this, health experts argue that countries must increase access to typhoid vaccines and invest in new antibiotic research. For example, a recent study in India estimates that if a child is vaccinated against typhoid fever in an urban area, it can prevent up to 36% of typhoid cases and deaths.

Pakistan is currently leading the way in this regard. It is the first country in the world to provide regular immunity to typhoid fever. Millions of children were vaccinated last year, and health experts argue that more countries need to follow suit.

Antibiotic resistance is one of the leading causes of death in the world, killing more people than HIV / AIDS and malaria. Vaccines, if available, are some of the best tools needed to prevent future disasters.

I have no time to lose.

The study was published in Lancet microorganisms..

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