A team of microbiologists has discovered a risk of microbes in intravenous drug use.
Researchers at Bowling Green State University studied the contents of 50 syringes from the Northwest Ohio Safe Services’ needle exchange program, where people who use drugs can swap out used needles for clean ones.
In addition to a mix of narcotics, they discovered a drug-resistant fungus that can cause serious infections.
“If the drugs don’t kill you, the microbes might,” said biological sciences professor Hans Wildschutte. “If you're injecting those directly into your vein, that's a problem.”
The substances found on syringes
Wildschutte said the researchers found a lot of what they expected on the needles: opioids, stimulants and other common narcotics. But, he was surprised to find that the majority of the syringes contained xylazine, a veterinary tranquilizer unapproved for human use.
“When we were doing this study, [xylazine] was relatively new. And we didn't think we'd find it in Toledo, but we did,” he said. “It was in almost every needle, and it was the highest component of all the drugs that were in the needles.”
He also discovered the presence of Candida, a fungus that can cause thrush and urinary infections and can infect bloodstreams. This sort of fungus is becoming increasingly common, he said.
“With global warming, they're able to survive at higher temperatures, which is required to survive in us because our body temperature is higher,” he explained.
Research published in the Open Forum Infectious Diseases in 2025 noted that these types of fungal infections have risen alongside intravenous drug use.
A need for solutions
It’s worrying, Wildschutte said, because currently there are limited treatment options for fungal infections. There are only a handful of medications that can treat them and Candida has evolved resistance to many of those that have worked in the past.
The consequences can be deadly for people injecting drugs, Wildschutte said.
“Most people, if you're healthy, you fight it off. But … because of the nature of their habit, they're not sleeping well, they're not in good health and if you're injecting this thing directly into your bloodstream, it certainly can kill you.”
He said the study’s findings have inspired his lab to focus on natural drug discovery. They noted that certain strains of a soil-based bacterium, called Pseudomonas, killed Candida.
“This study sort of pivoted our research to go towards anti-fungal drug discovery,” he said. “I think there will be more. Because the federal agencies, the NIH and other agencies, they are becoming aware of this and they're trying to allocate some of their funding to this research as well.”
