Difficult-to-treat infections caused by dangerous, drug-resistant bacteria are on an alarming upward climb, the Centers for Disease Control and Prevention (CDC) warned in a recent health alert.
Known colloquially as “nightmare bacteria” or “superbugs,” bacteria known as carbapenem-resistant Enterobacterales (CRE) have become significantly more common since 2019, just before the COVID-19 pandemic, CDC researchers found in a study published in the Annals of Internal Medicine on Sept. 23.
These bacteria are resistant to even some of the strongest antibiotics, making the nearly 70% increase in infections caused by them a potential public health issue, the CDC said.
“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, Danielle Rankin, an epidemiologist in CDC’s Division of Healthcare Quality Promotion, said in a Sept. 23 press release. “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.”
Here’s what to know about the bacteria and what makes it a “nightmare.”
What is ‘nightmare bacteria’?
“Nightmare bacteria” is an umbrella term coined by former CDC Director Tom Frieden in 2013. It refers to a category of antibiotic-resistant bacteria called carbapenem-resistant Enterobacterales, with “carbapenem” referring to a type of antibiotic and “Enterobacterales” describing a class of bacteria.
Carbapenems are not just everyday antibiotics: they are some of the most powerful, broad-spectrum antibiotics out there, often used to treat infections caused by drug-resistant bacteria, according to the National Institute of Health (NIH). If a person gets sick with an infection that can’t be treated by many or most common types of antibiotics, carbapenems are used.
They can be used for the treatment of complex and serious conditions, including multiple types of pneumonia, bacterial meningitis, urinary system infection, respiratory infections, blood infections and skin infections.
Bacteria become resistant to medications when they develop the ability to withstand drugs formulated to kill them, according to the CDC and Cleveland Clinic. Experts say this is chiefly the result of increased antibiotic use, as the more exposure bacteria get to specific types of antibiotics, the more time they have to form a resistance to them. This is why it’s generally considered important not to take antibiotics unless absolutely necessary, to limit use only to what is needed and to finish the full course as prescribed. These “superbugs” can also be transmitted from person to person, says the Cleveland Clinic.
CRE is often associated with hospital stays and clinical settings and is still considered rare, according to the study’s authors. However, the marked increase in these types of infections is still a concern, they said.
How and why is ‘nightmare bacteria’ spreading?
Authors of the study published in September looked at 4,341 cases of CRE infections from hospitals across 29 states. Overall, it found a 69% increase in carbapenem-resistant infections between 2019 and 2023, representing an increase to more than 3 per 100,000 from 2 per 100,000.
This increase was largely driven by the NDM gene, the study found. This gene produces an enzyme that resists antibiotics and, if it is present in bacteria, makes those bacteria extremely difficult to kill. NDM was once considered exceedingly rare in the U.S., but the study discovered a 460% increase in NDM-CRE infections between 2019 and 2023.
These forms of infection could pose a serious risk in healthcare settings, the study’s authors said, as they are not only most likely to spread there, but can only be treated via two uncommon and expensive antibiotics administered via an IV. This means something considered common, like a urinary tract infection, that is usually treated with oral antibiotics taken at home may have to be treated through hospitalization if bacteria with NDM are present.
The study’s authors noted that it’s likely many carriers of CRE do not know they carry the bacteria, making community spread a risk. There were also limitations to their ability to fully assess the situation in the study, as some hospitals are not equipped to perform the proper testing and reporting. Several densely populated states, including California, New York, Florida and Texas, were also not included in the research.
The CDC notes that CRE can spread through person-to-person contact from dirty hands, wounds, and stool or contaminated medical equipment and devices. People who are taking long courses of certain antibiotics, use medical devices such as respirators and catheters, and those with weakened immune systems are at the highest risk of contracting a CRE infection, said the CDC.
Another study published in the Annals of Internal Medicine in April found that antibiotic-resistant infections increased from 182 to 193 per 10,000 hospitalizations during and following the COVID-19 pandemic, indicating that increased hospitalization and exposure to antibiotics could also play a role in the increase of such infections. In a 2022 special report, the CDC found that there were approximately 12,700 infections and 1,100 deaths in the U.S. due to CRE in 202.
