The hands of a nurse can be seen holding a syringe. A nurse in New York allegedly diluted syringes containing hydromorphone with tap water, causing six cancer patients to develop a rare blood infection, federal prosecutors said. (Picture Alliance/Getty Images)

Medical professionals at the Roswell Park Comprehensive Cancer Center in Upstate New York knew something wasn’t right. Within one week, three patients had been diagnosed with the same rare blood infection.

Between June and July of last year, six people being treated at the cancer center in Buffalo were sickened by a waterborne bacteria called Sphingomonas paucimobilis, according to a report published Wednesday in the New England Journal of Medicine. The bacterium is found in water and soil, but seldom leads to bloodstream infections, even in people such as cancer patients with compromised immune systems, experts from Roswell Park noted in the report.

So why were there suddenly such an unusually high number of cases?

The center’s staff searched everywhere for answers, checking with regional microbiology labs, the Food and Drug Administration and pharmaceutical vendors, the report said. When those efforts failed to turn up any solid clues, they started looking at their own employees, and an explanation soon became clear.

Several syringes of hydromorphone, an opioid known as Dilaudid, tested positive for the bacterium, and records showed that a nurse “had repetitively and inappropriately accessed” the locked drawer containing the medication, the report said.

“We concluded that a portion of the narcotic had been removed and replaced with an equal volume of tap water,” which led to the contamination, the report’s authors wrote. While three people infected ultimately died, their deaths were not linked to the bacterium, which was treated with antibiotics, according to the report.

Wednesday’s report did not name the nurse, but the description of the person’s actions matched details of an ongoing federal case. In June, prosecutors charged Kelsey A. Mulvey of Grand Island, N.Y., a registered nurse who worked at Roswell Park, with illegally obtaining controlled substances by fraud and tampering, and violating the Health Insurance Portability and Accountability Act (HIPAA). The charges carry a maximum penalty of 10 years in prison and a $250,000 fine, according to a news release from the U.S. attorney’s office in the Western District of New York.

“Once again, this case illustrates the destructive power of opioid addiction,” U.S. Attorney James P. Kennedy Jr. said in the release. “In this case, however, the harm caused by defendant’s actions resulted not only in harm to herself but in harm to some of the most compromised and vulnerable individuals in our community — those members of our community receiving cancer treatments. If we fail to take action to protect the most vulnerable among us, then we fail as a government.”

A multiagency investigation involving the FDA and the FBI revealed that over the course of several months last year, Mulvey allegedly tampered with medicine at the center, stealing drugs such as hydromorphone, methadone and oxycodone. As a result, officials allege that 81 patients didn’t receive their proper medication between February and June 2018.

In a June court appearance, a tearful Mulvey pleaded not guilty, the Buffalo News reported. A public defender representing Mulvey did not respond to a request for comment late Wednesday.

Authorities believe Mulvey accessed the drugs through an automated medication dispensing system used at the center called a Pyxis machine, according to a criminal complaint. Logs showed that Mulvey frequented machines on floors where she wasn’t assigned or didn’t have any patients, which was not commonly done at the center. She also used the machine on her days off, the complaint said.

A witness later recalled seeing Mulvey open her locker at work and “more than a dozen insulin type syringes fell onto the floor,” according to the complaint. The syringes were “used, recapped and had blood at the ends,” the witness, a registered nurse who worked with Mulvey, said.

Mulvey, the witness noted, was behaving like “a cat on a hot tin roof.”

By June 20, 2018, three cancer patients had been infected by the waterborne bacteria. The next day, a fourth patient was confirmed, followed by two more in July. According to a chart included in the complaint, the center normally sees only one to two cases of the infection each year. In Wednesday’s journal report, experts wrote that the “Sphingomonas species can cause hospital-associated infections from various environmental exposures, including reservoirs within the hospital plumbing.”

About a week after the first infected patients were diagnosed, Mulvey was seen leaving one of the center’s medication rooms on June 27, 2018, with a backpack when she was supposed to be on vacation, the complaint said. A nursing supervisor “deemed this conduct suspicious,” and reported it. The following day, Mulvey was placed on administrative leave pending an investigation, authorities said.

At the time, investigators said the locked drawer Mulvey allegedly accessed contained seven Dilaudid syringes, which were “immediately removed from the Pyxis and sequestered.”

Tests of the seven syringes revealed that four of them grew the waterborne bacteria, the complaint said. Those four also had “approximately 80% of the product removed and replaced,” according to the documents.

During a meeting in July 2018, Mulvey’s employers accused her of drug diversion — illegally using medicine intended for other people — and “potentially manipulating syringes” to cause the outbreak, documents said. She denied the allegations and resigned in lieu of being fired.

Investigators, however, said they obtained text messages in which Mulvey talked to her brother “about her addiction to Dilaudid and the potential charges she may be facing.” According to the complaint, the texts were sent July 15, 2018, two days after Mulvey resigned.

“[I] don’t know why I let it get so bad,” Mulvey texted. In subsequent messages, she expressed concerns about losing her nursing license, writing, “that’s all I worked for in school.”

Authorities have come across cases like Mulvey’s before, FBI Buffalo Special Agent in Charge Gary Loeffert said in June.

“This is not the first time we have investigated and charged a healthcare professional who suffers from addiction,” Loeffert said in the release from the prosecutor’s office. “Accessibility to these highly sought-after drugs makes it easier for medical professionals to feed their addiction.”

In May 2018, an emergency room nurse in Washington state allegedly exposed patients to hepatitis C while stealing drugs because she used her own needle to administer their medication, The Washington Post’s Lindsey Bever reported. Facing the allegations, the nurse resigned and her license was suspended.

On Wednesday, the authors of the journal article wrote that in response to the incident the center beefed up its security system, which included installing video monitors, and worked to educate its staff about how handle such situations.

The Roswell Park staff added that the case could help other medical centers link unusual spates of bacterial infection to drug theft.

“We share our experience to alert health care providers that, in this age of profound prevalence of opioid addiction, drug diversion is an important consideration when a cluster of waterborne bacteremia is identified,” they wrote.

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