In a development that has startled scientists and public health officials alike, the United States has seen a dramatic surge in infections caused by so-called "nightmare bacteria"—a term used for drug-resistant bacteria that are notoriously hard to treat and potentially deadly. According to a series of new reports from the Centers for Disease Control and Prevention (CDC), cases of patients infected with bacteria carrying the New Delhi metallo-beta-lactamase (NDM) gene have soared by an astonishing 70% between 2019 and 2023.
These findings, published in the Annals of Internal Medicine and highlighted in a CDC report released on Tuesday, September 23, 2025, reveal a public health challenge that is both urgent and complex. The rise is driven by bacteria known as NDM-producing carbapenem-resistant Enterobacterales (NDM-CRE), which are resistant to most antibiotics, including carbapenems—often considered the last line of defense against severe bacterial infections.
To put the numbers in perspective, researchers counted 4,341 cases of carbapenem-resistant bacterial infections from 29 states in 2023. Of those, 1,831 were of the NDM gene variety. The rate of carbapenem-resistant infections increased from just under 2 per 100,000 people in 2019 to more than 3 per 100,000 in 2023—a 69% jump. Even more startling, the rate of NDM cases alone skyrocketed from about 0.25 to about 1.35 per 100,000 people, representing a 460% increase, as reported by The Associated Press and corroborated in the CDC's own analysis.
"The rise of NDMs in the U.S. is a grave danger and very worrisome," said David Weiss, an infectious diseases researcher at Emory University, in an email to The Associated Press. The sentiment is echoed by Danielle Rankin, an epidemiologist in the CDC's Division of Healthcare Quality Promotion, who warned, "This sharp rise in NDM-CRE means we face a growing threat that limits our ability to treat some of the most serious bacterial infections." She added, "Selecting the right treatment has never been more complicated, so it is vitally important that healthcare providers have access to testing to help them select the proper targeted therapies."
NDM-CRE infections can manifest as pneumonia, bloodstream infections, urinary tract infections, and wound infections. What makes them particularly alarming is their resistance to nearly all available antibiotics, leaving only two treatment options—both of which are expensive and must be administered intravenously. This resistance is due to the NDM enzyme, which allows bacteria to neutralize even the most potent antibiotics.
Historically, NDM gene bacteria were considered "exotic" and were mostly linked to patients outside the United States. However, the recent spike in cases suggests these bacteria are no longer rare or confined to overseas travelers. The CDC noted that common infections once considered routine—such as urinary tract infections—can become chronic or even life-threatening if caused by NDM-CRE.
The surge in drug-resistant infections is not entirely unexpected. Experts point to the misuse of antibiotics as a key driver. This includes patients not finishing prescribed courses or taking unnecessary antibiotics, which allows bacteria to survive and adapt. According to the CDC, the COVID-19 pandemic may have played a significant role as well. "We know that there was a huge surge in antibiotic use during the pandemic, so this likely is reflected in increasing drug resistance," Dr. Jason Burnham, a Washington University researcher, told The Associated Press.
Another challenge is that many people may be unrecognized carriers of the drug-resistant bacteria, potentially leading to community spread. "It's likely many people are unrecognized carriers of the drug-resistant bacteria, which could lead to community spread," Weiss cautioned, as cited by Christopher Sadowski. This makes the task of containment even more daunting.
Testing and reporting gaps further complicate the picture. Many states do not fully test or report cases of NDM-CRE, and some hospitals lack the necessary laboratory capacity to detect these dangerous germs. As a result, the CDC's estimates are likely only a partial snapshot of the true infection rates. Notably, the agency did not have data from some of the country's most populous states, including California, Florida, New York, and Texas. "The total number of nationwide infections is definitely underestimated," Burnham said.
This problem is not unique to the United States. The CDC and international health agencies have observed similar trends in other regions. In South Asia, NDM-producing bacteria are relatively widespread, especially in India and Pakistan, due to overuse of antibiotics and weaker infection control. Southern European countries like Greece and Italy also report higher rates, while in Africa and Latin America, underreporting and weak health systems exacerbate the threat.
Given the global nature of the problem, experts stress the need for coordinated action. The CDC urges healthcare providers to stay informed about local and national trends, test promptly for carbapenemase-producing bacteria, and select treatments carefully based on resistance mechanisms. Infection prevention and control measures—such as hand hygiene, use of gloves and gowns, and proper cleaning—are more crucial than ever.
For patients, the early signs of carbapenem-resistant infections can be subtle and easily mistaken for common bacterial illnesses. Symptoms might include burning sensations or cloudy urine in urinary tract infections, high fever or low blood pressure in bloodstream infections, and cough or chest pain in pneumonia. Because these symptoms are so commonplace, clinicians might not initially suspect a drug-resistant infection, leading to delays in effective treatment.
The stakes are high. In 2020, the CDC estimated there were approximately 12,700 CRE infections and 1,100 associated deaths in the U.S. The rapid rise of NDM-CRE threatens to push these numbers higher, especially as detection and reporting remain inconsistent.
Ultimately, the battle against "nightmare bacteria" will require a multi-pronged approach—improving antibiotic stewardship, expanding laboratory capacity, enhancing infection control, and fostering global cooperation. As bacteria continue to evolve, so too must our strategies to stay ahead of the next public health threat.
