A health care worker contracted hepatitis C after injuring herself on a needle, it has emerged.
Worcestershire Acute Hospitals NHS Trust has been fined £12,5000 after admitting breaching health and safety laws back in February 2007.
The court case was brought by the Health and Safety Executive (HSE) which said the healthcare worker's infection had been preventable.
A trust spokesman said improvements to systems had been made since.
The hospital trust was also ordered to pay an additional £9,500 costs.
Magistrates in Worcester heard the worker, who has not been named, had taken blood from a patient known to be infected with the virus.
She then had difficulty disposing of the needle in the correct bin, as other equipment was in the way.
She put the needle on a work surface but caught her wrist on it as she reached across for a tissue.
Speaking after the hearing, the HSE said the staff member had not been made aware of the patient's infection and she had not been supervised during the procedure. She had been training at the trust for three weeks when the injury happened.
An HSE spokeswoman said: "This infection was entirely preventable.
"The risks and controls are well known and the trust should have had an effective safe system of work in place."
John Rostill, chief executive of the trust, apologised to the staff member and said the trust had co-operated fully with the HSE investigation.
"On this occasion the trust accepts it fell below the health and safety standards expected," he said.
"An immediate plan of action was put in place and we are confident that the necessary investment and improvements have been made to minimise the risk of such an incident happening again."