In nature, it's a dog-eat-dog world, even in the realm of bacteria. Competing bacteria use "toxic darts" to disable each other, according to a new study by UC Santa Barbara biologists. Their research is published in the journal Nature.
Â
"The discovery of toxic darts could eventually lead to new ways to control disease-causing pathogens," says Stephanie K. Aoki, first author and postdoctoral fellow in UCSB's Department of Molecular, Cellular, and Developmental Biology (MCDB). "This is important because resistance to antibiotics is on the rise."
Â
Second author Elie J. Diner, a graduate student in biomolecular sciences and engineering, notes, "First we need to learn the rules of this bacterial combat. It turns out that there are many ways to kill your neighbors; bacteria carry a wide range of toxic darts."
Â
The scientists studied many bacterial species, including some important pathogens. They found that bacterial cells have stick-like proteins on their surfaces, with toxic dart tips. These darts are delivered to competing neighbor cells when the bacteria touch. This process of touching and injecting a toxic dart is called "contact dependent growth inhibition," or CDI.
Â
Some targets have a biological shield. Bacteria protected by an immunity protein can resist the enemy's disabling toxic darts. This immunity protein is called "contact dependent growth inhibition immunity." The protein inactivates the toxic dart.
Â
The UCSB team discovered a wide variety of potential toxic-tip proteins carried by bacteria cells nearly 50 distinct types have been identified so far, according to Christopher Hayes, co-author an associate professor at MCDB. Each bacterial cell must also have immunity to its own toxic dart. Otherwise, carrying the ammunition would cause cell suicide.
Â
Surprisingly, when a bacterial cell is attacked and has no immunity protein it may not die. However, it often ceases to grow. The cell is inactivated, inhibited from growth. Similarly, many antibiotics do not kill bacteria; they only prevent the bacteria from growing. Then the body flushes out the dormant cells.
Â
Some toxic tips appear to function inside the targeted bacteria by cutting up enemy RNA so the cell can no longer synthesize protein and grow. Other toxic tips operate by cutting up enemy DNA, which prevents replication of the cell.
Â
"Our data indicate that CDI systems are also present in a broad range of bacteria, including important plant and animal pathogens such as E. coli which causes urinary tract infections, and Yersinia species, including the causative agent of plague," says senior author David Low, professor of MCDB. "Bacteria may be using these systems to compete with one another in the soil, on plants, and in animals. It's an amazingly diverse world."
Â
The team studied the bacteria responsible for soft rot in potatoes, called Dickeya dadantii. This bacteria also invades chicory leaves, chrisanthemums, and other vegetables and plants.
Â
Funding for this research came from the National Science Foundation and the National Institutes of Health. The TriCounty Blood Bank also provided funding.
Â
The research was performed in the Low and Hayes lab in MCDB. Important contributions were made Stephen J. Poole, associate professor in MCDB, and by Peggy Cotter's lab when she was with MCDB. Cotter has since moved to the University of North Carolina School of Medicine. Other co-authors include Claire t'Kint de Roodenbeke, research associate; Brandt R. Burgess, postdoctoral fellow; Bruce A. Braaten, research scientist; Alison M. Jones, technician; and Julia S. Webb, graduate student.
Â
Â
Stay prepared and protected with Infection Control Today's newsletter, delivering essential updates, best practices, and expert insights for infection preventionists.
Flawed From the Start: Why Many IFUs for Surgical Instruments Fail in Real-World Sterile Processing
July 23rd 2025At the 2025 HSPA Annual Conference & Expo, Cori L. Ofstead, MSPH, highlighted critical flaws in manufacturers’ instructions for use (IFUs) for orthopedic and neurosurgical instruments. From contradictory directions to unrealistic cleaning expectations, these IFUs often fail under real-world conditions, jeopardizing both patient safety and sterile processing workflows.
US Withdrawal From UNESCO Signals a Dangerous Step Back for Global Science
July 22nd 2025In a decision heavy with consequence and light on foresight, the US has once again chosen to walk away from UNESCO, leaving behind not just a seat at the table, but a legacy of global scientific leadership that now lies in question.
Pathogen Pulse: Facilities Need the SPD, Yersinia Enterocolitica Outbreak, and More
July 22nd 2025From unsterilized surgical tools in Colorado to a years-long methicillin-resistant Staphylococcus aureus (MRSA) outbreak in Virginia and a surging measles crisis in Canada, recent headlines reveal the fragile front lines of infection prevention and the high stakes when systems fail.
Telemedicine's Transformative Role in PPE Distribution and Sterile Equipment Management
July 22nd 2025In an era defined by digital transformation and post-pandemic urgency, telemedicine has evolved beyond virtual visits to become a vital infrastructure for delivering personal protective equipment (PPE) and managing sterile supplies. By enabling real-time forecasting, remote quality control, and equitable distribution, telemedicine is revolutionizing how health care systems protect both patients and providers.
Reducing Hidden Risks: Why Sharps Injuries Still Go Unreported
July 18th 2025Despite being a well-known occupational hazard, sharps injuries continue to occur in health care facilities and are often underreported, underestimated, and inadequately addressed. A recent interview with sharps safety advocate Amanda Heitman, BSN, RN, CNOR, a perioperative educational consultant, reveals why change is overdue and what new tools and guidance can help.
New Study Explores Oral Vancomycin to Prevent C difficile Recurrence, But Questions Remain
July 17th 2025A new clinical trial explores the use of low-dose oral vancomycin to prevent Clostridioides difficile recurrence in high-risk patients taking antibiotics. While the data suggest a possible benefit, the findings stop short of statistical significance and raise red flags about vancomycin-resistant Enterococcus (VRE), underscoring the delicate balance between prevention and antimicrobial stewardship.