New research from Bowling Green State University has confirmed what many in public health have long suspected: shared needles carry far more than viruses. A study conducted in partnership with the Toledo Lucas County Health Department found that the average used needle contained eight different compounds, that 86 per cent of needles tested contained xylazine, a powerful veterinary tranquiliser, and that the dangerous fungal pathogen Candida was present in samples taken from a local needle exchange programme.

The findings, published in PLOS One, point to a cascade of compounding health risks that extend well beyond what most drug users, and indeed many clinicians, are currently prepared for.

What Was in the Needles

The BGSU research team, led by biological sciences professor Hans Wildschutte, analysed used hypodermic needles collected through Northwest Ohio Safe Services, the county’s needle exchange programme. The goal was to identify not just what narcotics were present, but whether non-viral pathogens had been introduced into the drug supply.

The results were stark. Shared needles from the programme contained an average of eight distinct compounds, a figure that suggests most users have little to no idea what they are actually injecting. The near-universal presence of xylazine, found in 86 per cent of needles, is particularly alarming, given that it is not an opioid and therefore does not respond to naloxone, the standard overdose reversal medication.

But it was the discovery of Candida that most surprised the researchers.

“We thought there was just going to be bacteria in there, so when there was Candida, for me, that was a big surprise,” said Wildschutte.

Why Candida Is a Serious Concern

Candida is a fungal pathogen more commonly associated with thrush or urinary tract infections. In healthy individuals, it is manageable. In people who inject drugs, many of whom are immunocompromised or in poor general health, a Candida infection entering the bloodstream can be life-threatening.

Nara Souza, a BGSU doctoral student who worked on the project, outlined why this matters not only for individuals but for the broader health system.

“We see Candida is already in a lot of hospitals in quite a few states, which is a big concern because we don’t have as many antifungal treatments, especially when compared to antibiotics,” Souza said. “The antifungal medications can have more side effects and can even be toxic to humans, which can limit treatment options. And in addition, the diagnostic testing for fungal infections is more difficult and takes longer.”

The related strain Candida auris, a multidrug-resistant species not directly studied in this research, has already been identified in hospitals across 27 US states, adding urgency to findings about Candida’s presence in shared needles. The overlap between intravenous drug use and hospital-based fungal infection is no longer theoretical.

A Bacterial Ally in an Unlikely Place

Despite the gravity of these findings, the research produced one genuinely hopeful result. Scientists identified strains of Pseudomonas, a soil-based bacterium, that were capable of killing Candida. Biological sciences graduate student Michael Fyfe described the potential implications.

“We did see some novel interactions that could lead us to some exciting places if we explore this further,” Fyfe said. “There were times that we were able to, in essence, edit the genome to produce more of the antifungal compound.”

The ability to manipulate Pseudomonas to increase its antifungal output opens a possible route to natural drug discovery, potentially offering a new class of treatment for fungal infections at a time when antifungal options are limited and resistance is growing.

“Every time we do these tests, it’s really remarkable that these bacterial strains are able to kill not only these dangerous fungi, but even some multi-drug-resistant pathogens,” Wildschutte said.

A Broader Public Health Picture

The wider context here cannot be overlooked. More than 100,000 Americans have died each year from drug-related causes since 2021. Fungal infections, meanwhile, kill approximately two million people worldwide annually, a figure that is rising year on year.

What this research suggests is that the two crises may be more tightly linked than public health systems currently account for. Shared needles are not simply conduits for HIV or hepatitis. They are introducing a complex, poorly understood mix of chemical compounds and biological pathogens directly into the bloodstream, many of which carry their own independent risk of death.

The BGSU findings reinforce what the evidence has long indicated: that intravenous drug use carries layered, compounding harms that extend far beyond the substance itself. The presence of Candida in needle exchange samples is not a peripheral finding. It is a signal that the full health burden of injecting drug use is still being measured.

Further research is underway.

Source: dbrecoveryresources