A failed sterilization process likely caused bacterial infections in 19 Alabama patients who received contaminated intravenous nourishment, a health official said on Thursday.
But officials still don't know whether the deaths of nine of those patients resulted from the outbreak of Serratia marcescens bacteremia, a bacterial infection of the blood.
Nineteen patients at six hospitals received total parenteral nutrition -- a solution injected intravenously to people who cannot tolerate food by mouth or a feeding tube.
Tests showed that the bacteria found in the nutritional solution at a Birmingham pharmacy was the same strain identified in blood samples from 12 of the patients, said Donald Williamson, director of the Alabama Department of Public Health.
That finding rules out the possibility that the patients were infected by something other than the solution.
Williamson said it is not yet clear whether the filter used in the sterilization process was defective or if there was a breakdown in the overall procedures.
"We are not done ... We'll be working with the regulatory entities to try to understand exactly what went wrong in the sterilizing process," Williamson said during a conference call with reporters.
"We've identified where the weak point in the chain of infection control occurred ... We're now trying to identify exactly what happened," he added.
The investigation is expected to continue for several more weeks, officials said.
Birmingham pharmacy Meds IV produced the nutritional solution. After learning of the outbreak last month, the company recalled all of its IV compound products, health officials said.
Meds IV could not be reached for comment on Thursday. A voice mailbox was full, and the pharmacy's Web site has been taken down.
Health officials said the infected patients' ages ranged from 38 to 94. Seventeen cases were reported in March, and two other cases from January and February were identified retrospectively.
As of Thursday, families of infected patients had brought four lawsuits against Meds IV and some of the hospitals.
Donald J. Mottern filed suit over the death of his 71-year-old mother, LaVonne.
"I would just like to have confidence back in our healthcare system," he said.