Ten people were hospitalized and one was found dead after contracting staph infections from injections received at health clinics in Delaware and Arizona in early spring, according the Center for Disease Control and Prevention.
The infection clusters were described in the latest Morbidity and Mortality Weekly Report.
Seven people were infected at a Delaware orthopedic clinic and four people at a pain management clinic in Arizona after receiving injections from drug vials intended for use with a single patient but that were instead used multiple times, the report and state health officials said.
Patients at the Arizona clinic were infected with methicillin-resistant Staphylococcus aureus, or MRSA, and patients in both outbreaks were hospitalized.
One patient was found dead at home six days after receiving treatment at the Arizona clinic, but the report says Arizona officials didn't declare MRSA the official cause of death.
The outbreaks are two of 20 that have been caused by misuse of single-dose vials since safety standards were reinforced in 2007, according to the CDC.
Needles or syringes weren't reused in either clinic, according to Arizona and Delaware state health officials, unlike a high-profile series of hepatitis C infections at a clinic in Las Vegas a few years back. But vials containing drugs intended for one person were used multiple times.
Drugs in single-use vials lack preservatives that prevent the growth of bacteria and subsequent spread of infections between people, CDC spokeswoman Rosa Herrera told Shots.
Health workers sometimes reuse vials when the amount of medicine they contain exceeds the dose needed for a single patient. One factor in the Delaware outbreak was a national shortage of single-dose vials of the anesthetic bupivacaine.
"Medications come in very large vials, but they're often only approved for use in one person," Herrera said. "Health care providers see that as waste. There's a desire to use what you've paid for. And they don't understand that they're putting their patients at risk."
Herrera said CDC is urging clinics dealing with shortages to split doses safely in pharmacies not where patients receive treatment.
Of the ten patients hospitalized, the stays ranged from three to 41 days. One patient treated in Arizona also needed long-term care, according to the report.
According to Delaware and Arizona health officials, both clinics remain in operation.