Every patient had undergone IV placement using contaminated gel
In the summer of 2024, a rare bacterium began appearing in the bloodstreams of patients across Minnesota hospitals — not through person-to-person spread, but through a contaminated bottle of ultrasound gel used during routine emergency procedures. Investigators at Abbott Northwestern Hospital and the Minnesota Department of Health, armed with whole genome sequencing, traced the genetic fingerprints of each infection back to a single source, revealing how a commonplace medical supply had become a hidden conduit of harm. The case, which ultimately prompted a national CDC safety alert in May 2025, stands as a quiet testament to the power of looking closely — and to the unsettling truth that preventable dangers can persist in plain sight until the right questions are asked.
- A cluster of bloodstream infections caused by an almost unheard-of bacterium, Paraburkholderia fungorum, began surfacing across multiple Minnesota hospitals in August 2024, triggering urgent questions about a possible shared source.
- Whole genome sequencing revealed the bacteria from different patients were genetically near-identical — meaning these were not isolated coincidences but a connected outbreak with a single origin.
- The critical link emerged when a contaminated bottle of nonsterile ultrasound gel tested positive for the same organism, matching the genetic profile found in patients' bloodstreams and confirming the transmission route.
- Every affected patient had received an IV catheter in an emergency department where nonsterile ultrasound gel guided needle placement — the gel coating the probe had delivered bacteria directly into the bloodstream at the moment of skin puncture.
- The CDC issued a national patient safety alert in May 2025, directing hospitals to use only sterile ultrasound gel for any procedure that breaks the skin, while Allina Health removed contaminated products and updated protocols systemwide.
In August 2024, Minnesota's public health officials noticed something that shouldn't exist: a cluster of bloodstream infections caused by Paraburkholderia fungorum, a bacterium so rare that most clinicians had never seen it. Infection preventionist Ellie Carter and colleagues at the Minnesota Department of Health began asking whether these cases were connected. Whole genome sequencing provided the answer — the organisms from different patients across multiple facilities were genetically near-identical, pointing unmistakably to a shared source.
The breakthrough came from an unexpected direction. A colleague in Israel had isolated the same bacterium from a bottle of nonsterile ultrasound gel. When the Minnesota Department of Health tested gel products in use at Allina Health facilities, one bottle came back positive — and its genetic profile matched the bacteria found in patients' blood. The connection was no longer theoretical.
A review of patient records revealed a pattern of complete consistency: every person who developed P. fungorum bacteremia had undergone IV catheter placement in an emergency department, and in every case, nonsterile ultrasound gel had been used to guide the procedure. When the needle broke the skin, it carried contaminated gel directly into the bloodstream. This was a pseudo-outbreak — not person-to-person transmission, but a contaminated product silently causing serious harm.
When findings were shared with the CDC, the agency acted swiftly. In May 2025, a national patient safety alert was issued recommending that sterile ultrasound gel be used exclusively for any percutaneous procedure. Allina Health removed the contaminated products and reinforced the new standard across its system.
The case endures as a model of modern outbreak investigation — genetic evidence connecting the dots, classical epidemiology explaining how contamination reached patients, and neither approach sufficient without the other. It is also a sobering reminder that even in well-monitored hospitals, preventable sources of infection can persist until someone looks closely enough to find them.
In August 2024, Minnesota's public health department noticed something unusual: a cluster of bloodstream infections caused by Paraburkholderia fungorum, a bacterium so rare that most clinicians have never encountered it in practice. What began as a handful of isolated cases across different hospitals would eventually unravel into a story about contaminated medical supplies, the power of genetic detective work, and a preventable source of harm hiding in plain sight.
Ellie Carter, an infection preventionist at Abbott Northwestern Hospital in Minneapolis, and her colleagues at the Minnesota Department of Health began asking the standard questions: Were these cases connected? Was there a common thread? Using whole genome sequencing—a tool that has become increasingly central to outbreak investigations—they compared the genetic makeup of the bacteria isolated from different patients. The results were striking. The organisms were closely related, suggesting they all came from the same source rather than representing random, unrelated infections. This genetic fingerprinting allowed investigators to connect what might otherwise have seemed like separate incidents across multiple facilities, even across international borders.
The breakthrough came from an unexpected direction. A colleague in Israel had isolated the same bacterium from a bottle of nonsterile ultrasound gel. Around the same time, the Minnesota Department of Health lab tested ultrasound gel products being used at Allina Health facilities. One bottle came back positive for P fungorum, and when they sequenced the organism, it matched the genetic profile of the bacteria found in patients' bloodstreams. The connection was no longer theoretical—it was concrete.
Infection prevention teams then reviewed the medical records of every patient who had developed P fungorum bacteremia within the health system. A pattern emerged with complete consistency: every single patient had undergone placement of a peripheral intravenous catheter in an emergency department. And in each case, nonsterile ultrasound gel had been used during the procedure. The ultrasound probe, meant to guide the needle into the vein, had been coated with contaminated gel. When the needle pierced the skin, it carried bacteria directly into the bloodstream.
This was not a traditional outbreak in the sense of person-to-person transmission. It was what epidemiologists call a pseudo-outbreak—a cluster of infections stemming from contamination of a medical product rather than from the spread of disease between patients. But the consequences were just as real. Multiple patients had developed serious bloodstream infections from a source that should never have been there.
When investigators shared their findings with the CDC, the agency responded with urgency. In May 2025, the CDC issued a national patient safety alert recommending that sterile ultrasound gel be used exclusively before and during any percutaneous procedure—any procedure in which a needle or instrument breaks the skin. Allina Health implemented a systemwide safety advisory reinforcing the same message to its staff. The contaminated gel bottles were removed from circulation.
The case illustrates how modern molecular epidemiology works in practice. Whole genome sequencing provided the genetic evidence that connected seemingly isolated cases. Traditional epidemiology—careful chart review, timeline analysis, identification of common exposures—provided the human context that explained how the contamination had reached patients. Neither approach alone would have been sufficient. Together, they revealed a hidden source of harm and prompted a national change in practice.
As health care-associated infection surveillance becomes more sophisticated, investigators say this model of combining classical detective work with advanced molecular techniques will remain essential. The contaminated ultrasound gel is gone. The protocols have changed. But the case serves as a reminder that even in modern hospitals, with all their technology and oversight, preventable sources of infection can persist until someone looks closely enough to find them.
Citas Notables
This investigation highlights the importance of whole genome sequencing to inform genomic epidemiology and the importance of clinical and public health collaboration to identify outbreaks.— Carter and colleagues
La Conversación del Hearth Otra perspectiva de la historia
Why did it take genomic sequencing to find this? Couldn't traditional epidemiology have caught it?
Traditional epidemiology alone might have missed it entirely. Without the genetic evidence showing all the cases were connected, investigators might have assumed they were dealing with separate, unrelated infections. The sequencing proved they had a common source.
So the gel was contaminated at the factory, or somewhere in the supply chain?
The source material doesn't specify where the contamination originated—only that the bottles being used in the emergency department were contaminated. That's actually a separate investigation.
Every single patient had an IV placed in the ED with that gel. That's a perfect correlation.
Exactly. Once they looked at the medical records, the pattern was unmistakable. Every patient, same procedure, same gel. That's what made the epidemiological link so strong.
And this was happening across multiple hospitals?
Yes, which is why the genetic connection was so important. Cases were scattered across different facilities, even different countries. Without WGS, they would have looked like unrelated events.
What happens now? Is there oversight of ultrasound gel sterility?
The CDC issued a national alert recommending sterile gel only. Hospitals like Allina implemented new protocols. But the case also raises questions about how contaminated products circulate in the supply chain in the first place.