Six Carson City firefighters undergoing yearly tuberculosis screening were accidentally injected with a serum to combat tetanus.
Fire Department officials said the mistake was made by a nurse with Concentra Medical Centers, a company that contracts with the city to provide medical services.
"At this point, nobody is in danger. We are looking into what happened," said Tony Baker of Carson City's risk management office.
Fire Capt. Bob Schreihans said six of the 17 firefighters received the wrong shot before paramedic Tom Raw noticed that the vials the nurse was using were labeled "tetanus."
"When she saw the vial," Raw said, "she said, 'Oops!'"
He said the nurse was embarrassed and quickly corrected it, re-injecting those who had received the wrong medication with the proper one and finishing with the remainder of the firefighters.
A tetanus shot, given as a booster or to prevent infection from an injury, should be administered deeply into a muscle for slow release. If, as happened Tuesday, the shot is improperly administered, the tetanus antioxidant can cause swelling and skin ulcers, Raw said.
Firefighter J.R. Maxfield was one of those who received the wrong injections. He said a painful puss-filled sore that is hot to the touch, is growing on his arm. Eventually, it will burst and leave an ulcer, he suspects.
"Right now, my body is fighting the infection there," Maxfield said. "It hurts a little."
"Mistakes happen," Schreihans said. "But six times in a row is an issue. Concentra needs to look at their protocol."
Vicki Bryant, a Concentra spokeswoman in Dallas, said the company is investigating.
"The staff in our clinics are highly trained individuals," she said. "It is a primary goal of ours to make every encounter as safe as possible."
The company operates about 250 clinics nationwide that specialize in workers compensation issues, she said.