Hospital staff in Sussex have been told they risk missing their target on cases of the bug C. difficile (C. diff).
The Royal Sussex County Hospital in Brighton and the Princess Royal in Haywards Heath must not exceed 155 cases of C.diff by the end of March.
But bosses of the NHS trust which runs the two hospitals said they had already recorded 126.
Chief executive Duncan Selbie told staff they were "sailing close to the wind".
Each hospital trust's target for the number of C. diff cases is set by the government.
Infection control nurse consultant Valerie Unsworth said she welcomed Mr Selbie's message to staff.
"It is really about raising everybody's awareness about how we can work together to prevent these infections form occurring," she said.
"We have done incredibly well over the last few years and our C. diff infection rates have come down quite dramatically, but it is not just about numbers.
"It is about the fewer infections the better because every infection has an impact on the patient."