Yorkshire Ambulance Service NHS Trust was among 21 of 388 trusts nationwide given a warning by health watchdog the Care Quality Commission after failing to make the grade.
All trusts have to meet certain standards to be allowed to register with th
e commission. These conditions are legally enforceable and failure to act means trusts could be issued with warning notices and fines, or face prosecution or closure.
Yorkshire Ambulance Service was the only ambulance trust in the country not to meet its cleanliness requirements fully.
Examples of expected improvements include ensuring the decontamination of surgical equipment is up to scratch and developing tighter policies to tackle infections like MRSA, Clostridium difficile and legionella, which causes legionnaires' disease.
Yorkshire Ambulance Service has been given a deadline of June 30 to make improvement to allow the service full, unconditional registration with the commission.
Martyn Pritchard, chief executive of Yorkshire Ambulance Service, said: "We take these issues very seriously and carried out our own rigorous examination of infection prevention and control measures.
We've highlighted areas where we need to be better and have informed the Care Quality Commission accordingly. We've agreed with the commission that these areas will be sorted out in the next few weeks."
Barbara Young, chairman of the commission, said: "All trusts must remain vigilant and constantly review and strengthen their performance. In 21 trusts we need further assurance that they are meeting the regulations. We have placed rigorous conditions on these trusts' registration and will monitor them closely. We will not hesitate to use our enforcement powers to protect patients' safety where needed."
Scarborough and North East Yorkshire Healthcare NHS Trust was granted unconditional registration following excellent progress in infection control.
Figures for cases of C difficile were down 15 from last year and MRSA cases dropped by 11, beating the Government targets placed on both infections.
