Hospitals implement strict protocols to prevent the spread of bacteria which can be deadly for vulnerable patients with serious illnesses.
However, despite these efforts, new strains of bacteria continue to emerge and cause infections in hospitalized patients, resulting in nearly 100,000 deaths in the US annually.
In a new study, researchers at Washington University School of Medicine in St. Louis have discovered an unexpected source of these hospital-acquired infections: the patients themselves.
Researchers from a recent study on mice discovered that urinary tract infections (UTIs) can develop after the insertion of sterile tubes called catheters, even when there is no bacteria present in the bladder.
Catheters are often used in hospitals to empty the bladders of patients undergoing surgery. In the study, the insertion of the tubes activated dormant Acinetobacter baumannii (A. baumannii) bacteria that were hiding within bladder cells, resulting in the emergence, multiplication, and causing UTIs.
The findings, published in Science Translational Medicine on Jan 11th, indicate that screening patients for hidden reservoirs of harmful bacteria could enhance current infection-control measures and prevent fatal infections.
“You could sterilize the whole hospital, and you would still have new strains of A. baumannii popping up,” remarks co-senior author Mario Feldman. “Cleaning is just not enough, and nobody really knows why.”
This research implies that patients themselves could unknowingly bring bacteria into the hospital, and it has implications for infection control measures. When patients are scheduled for surgery with a planned catheterization, it may be possible to detect and treat the presence of bacteria in that person before the surgery to decrease the risk of a severe infection.
Acinetobacter baumannii (A. baumannii) is a major hazard to hospitalized patients, often causing urinary tract infections (UTIs) in those with urinary catheters, pneumonia in patients on ventilators, and bloodstream infections through central-line catheters.
These bacteria are known for their resistance to a wide variety of antibiotics, making infections caused by them hard to treat and potentially deadly.
In order to understand why A. baumannii UTIs are often linked with catheterization, co-senior authors Scott J. Hultgren, PhD and Feldman collaborated to conduct the research.
While UTIs in healthy individuals are typically caused by Escherichia coli (E. coli), research has shown that E. coli can remain dormant within bladder cells for months after an infection has been treated and can re-emerge causing a new infection.
Feldman and Hultgren looked into whether A. baumannii can hide within cells as E. coli can, together with co-first authors Jennie E. Hazen, a graduate student, and Gisela Di Venanzio, PhD, a professor of molecular microbiology. They looked at mice that had UTIs brought on by A. baumannii. Because healthy mice can resist A. baumannii, much like humans, they employed mice with compromised immune systems.
The researchers implanted catheters into the mice’s urinary tracts using a sterile approach after the illnesses had cleared up and there had been no bacteria seen in the mice’s urine for two months. Within 24 hours of the initial infection, almost half of the mice got UTIs caused by the same strain of A. baumannii.
“The bacteria must have been there all along, hiding inside bladder cells until the catheter was introduced,” Hultgren adds. “Catheterization induces inflammation, and inflammation causes the reservoir to activate, and the infection blooms.”
Many individuals who carry the bacteria may not be aware that they are sick since A. baumannii seldom manifests symptoms in normally healthy people, according to the study. In the course of doing this investigation, the researchers looked through the scientific literature and found that 2% of healthy individuals had A. baumannii in their urine.
“I wouldn’t put much weight on the precise percentage, but I think we can say with certainty that some percentage of the population is walking around with A. baumannii,” Feldman adds. “As long as they’re basically healthy, it doesn’t cause any problems, but once they’re hospitalized, it’s a different matter. This changes how we think about infection control. We can start considering how to check if patients already have Acinetobacter before they receive certain types of treatment; how we can get rid of it; and if other bacteria that cause deadly outbreaks in hospitals, such as Klebsiella, hide in the body in the same way. That’s what we’re working on figuring out now.”
Source: 10.1126/scitranslmed.abn8134
Image Credit: Getty