'Concerning': A Harmful Bacterium Triggering Diarrhea Is Proliferating in Los Angeles
A troublesome superbug causing diarrhea is causing issues in Los Angeles. Researchers have identified a concerning new variant of the Shigella bacterium in the region – one that is virtually impervious to most antibiotics employed against it.
Specialists at the University of California, Los Angeles, led the study, examining an unusual group of Shigella instances detected between 2023 and 2024. Each of these instances were found to feature an extensively drug-resistant (XDR) strain of the bacteria. Despite the patients recovering, the researchers voiced serious concerns, as this superbug is likely still active in LA, and possibly spreading elsewhere.
Shigella is commonly associated with diarrhea and various gastrointestinal issues. Although most infections result in a week-long bout of discomfort, the infection can sometimes lead to severe and even fatal complications, particularly in people with weakened or underdeveloped immune systems, such as young children. Annually, it's estimated that Shigella kills around 200,000 individuals worldwide, with around half a million cases reported in the U.S., causing hospitalization for thousands. This bacterium typically spreads via contaminated food or drink, but sexual transmission is also possible, often through anal contact among men who have sex with men.
Antibiotics are deployed to tackle severe Shigella infections or to manage symptoms in at-risk individuals. Unfortunately, just like many other bacteria, Shigella bacteria have learned to sidestep common antibiotics aimed at them. The most worrying strains are extensively drug-resistant, capable of overcoming numerous antibiotics. In their research, published this month in the Journal of Infection Control, UCLA researchers documented the detection of a new XDR strain of Shigella sonnei in three of their subjects.
The study revealed three instances within a three-month period between 2023 and 2024. Each case involved men with a history of sexual activity with other men, with one patient reporting that a recent sexual partner had been diagnosed with Shigella a week prior. Initial lab tests confirmed that they carried an XDR strain, defined as resistance to azithromycin, ciprofloxacin, ceftriaxone, trimethoprim-sulfamethoxazole, and ampicillin.
Genetic analysis conducted on the UCLA patients' samples revealed similarities between the strains, albeit distinct from past XDR strains found in other regions. According to researchers, this suggests the strain has been evolving and spreading in the area for some time.
“The detection of a novel XDR S. sonnei actively spreading in Los Angeles is alarming,” the scientists wrote.
Luckily, the cases themselves were still treatable, or they cleared up on their own. One patient, however, developed a severe infection and was hospitalized in intensive care. Upon detecting XDR resistance in real-time, doctors switched to an alternative drug, which appeared to work and resulted in a full recovery.
Despite these positive outcomes, the rise of XDR Shigella in the U.S. and globally represents a growing and serious public health challenge. XDR strains are harder to treat than usual Shigella infections, and the delay in identifying a suitable drug can potentially be fatal. Last year, the Centers for Disease Control and Prevention issued a public health advisory on the superbug, reporting that 5% of Shigella cases reported to the agency in 2022 were caused by XDR strains, up from 0% in 2015. Given the recent findings, the problem is likely to have worsened since then. And the UCLA researchers emphasize that more action is needed to identify and curtail the spread of these dangerous bacteria.
“These cases underscore the rapid expansion of XDR Shigella in the U.S. and the urgent need for appropriate detection and management,” they concluded.
The discovery of this XDR Shigella strain in Los Angeles highlights the importance of advancements in science and technology in the future development of antibiotics, as current treatments are becoming less effective against drug-resistant bacteria. Moreover, the rising prevalence of XDR Shigella infections globally calls for collaboration between healthcare providers, researchers, and public health organizations to develop strategies for early detection and effective treatment.
