The Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report said in each outbreak, the use of single-dose or single-use vials for more than one patient was associated with infection transmission.
In both investigations, clinicians reported difficulty obtaining the medication type or vial size that best fit their procedural needs, the report said.
The Arizona Department of Health Services was notified in April of a patient with fluid cultures positive for methicillin-resistant Staphylococcus aureus, who had undergone procedures recently at an outpatient pain management clinic.
"Investigations confirmed that the three MRSA-infected patients received pain injections on the same day, along with 25 other patients," the report said. "Two MRSA-infected patients received epidural steroid injections. Ten people, including the MRSA-infected patients, received contrast injections for radiologic imaging to guide medication needle placement."
The three Arizona patients with MRSA were hospitalized for nine to 41 days, with additional long-term acute care required for one patient. A fourth recipient was found deceased at home, six days after treatment at a clinic, the report said.
The Delaware Department of Health and Social Services was notified March 19 of seven patients admitted to a hospital with evidence of septic arthritis or bursitis.
Cultures from the affected sites -- knee, hip, ankle and thumb -- indicated all of the patients had MRSA. All seven required hospitalization from three to eight days.
"Previously, the orthopedic practice had used 10 milliliter single-use vials of bupivacaine for single-patient use," the report said. "When a national drug shortage disrupted the supply, staff began using larger vials of bupivacaine for multiple patients."