A diarrhea-causing superbug is stirring up trouble in Los Angeles. Researchers have tracked down a worrying new strain of Shigella bacteria in the area—one that resists almost every antibiotic thrown at it.

Scientists at the University of California, Los Angeles, conducted the study, looking at a unique group of Shigella cases discovered between 2023 and 2024. Each of the cases was found to carry an extensively drug-resistant (XDR) strain of bacteria. Although all victims have recovered, the researchers say their discovery is "alarming," especially since it's likely the superbug is still actively spreading in LA and possibly elsewhere.

Shigella is a common source of diarrhea and other stomach symptoms. While most cases only cause a week-long bout of misery that clears up on its own, the infection rarely causes serious, even fatal complications, especially in people who are frail or unwell. development immune system, such as small children. Shigella kills about 200,000 people worldwide every year; in the US, yes THINK which infects about half a million people each year, with thousands hospitalized as a result. The germ is usually spread through contaminated food or drink, but it can also be transmitted sexually. This latter type of transmission tends to occur more frequently through anal contact among men who have sex with men.

Antibiotics are used to treat severe Shigella infections or to control infections at higher risk of disease. But like many other bacteria, Shigella Bacteria are increasingly learning how to resist the most common antibiotics used against them. The most worrisome strains are widely drug-resistant, which means they can overcome a wide variety of antibiotics. In their paper, PUBLISHED this month in Journal of Infection ControlUCLA scientists detail the discovery of a new XDR strain of Shigella sonnei in three of their patients.

According to the report, the three cases were detected in a three-month period between 2023 and 2024. All three infections involved men with a history of having sex with other men, with one patient reported that a recent sexual partner of theirs was ill. diagnosed with Shigella a week earlier. Initial lab tests revealed that they carried an XDR strain, formally defined as having resistance to the antibiotics azithromycin, ciprofloxacin, ceftriaxone, trimethoprim-sulfamethoxazole, and ampicillin.

ULCA scientists conduct genetic analysis of samples collected from their patients. They found that all three patients had the same strain, although it was different from previous XDR strains identified in other parts of the world. That likely means this version has been evolving and spreading in the area for a long time, the researchers said.

"The discovery of a novel XDR S. sonnei The active spread in Los Angeles is alarming,” they wrote.

Fortunately, the cases themselves can still be treated or otherwise clear up on their own. One person developed a serious infection and ended up in intensive care as a result. But the real-time detection of XDR resistance in this case prompted doctors to switch to a different recommended drug that appeared to work and the patient finally recovered completely.

However, the emergence of XDR Shigella in the US and around the world is a serious and growing public health concern. These cases are obviously more difficult to treat than an average one Shigella infection, and a delay in finding the right drug that works against an XDR strain can be fatal. Last year, scientists from the Centers for Disease Control and Prevention released a public health advisory about the superbug. In the advisory, the CDC reports that about 5% of Shigella Cases reported by the agency in 2022 were caused by XDR strains, up from 0% in 2015. Given these latest cases, the problem has likely only gotten worse since then. And UCLA scientists say more needs to be done to identify and prevent the spread of dangerous bacteria.

“These cases highlight the rapid expansion of XDR Shigella in the US and there is an urgent need for appropriate analysis and management,” they wrote.