Clostridioides difficile infection (CDI)

Definition of healthcare-associated C. difficile infection

C. difficile infection is identified based on the presence of C. difficile in faecal samples by culturing or molecular biology methods (PCR). The sample result is excluded from HAIBA if it indicates a non-toxic strain of C. difficile.

This case definition only applies to patients above 2 years of age.

The case definition of C. difficile is based on the European definition approved by ECDC and is divided as follows:

”Hospital Onset - Healthcare-Associated C. difficile infection"(HOHA) and ”Community Onset - Healthcare-Associated C. difficile infection" (COHA).

Read more about the ECDC criteria defining C. difficile infection.

• The HOHA definition of C. difficile infection covers instances in which the positive sample falls within a period of >= 48 hours after healthcare contact was initiated until 48 hours after the healthcare contact concluded.
• COHA covers instances in which infections are likely associated with hospital contact, but diagnosis occurs after hospital discharge or after outpatient courses and treatments have concluded. The COHA definition for C. difficile infection covers instances in which the positive sample was taken from 48 hours to 30 days after hospital contact. C. difficile infections also fall into this category if the positive sample was taken within 48 hours of admission and if the patient has had any contact with a hospital in the 30 days leading up to admission.

Which department/hospital is the infection attributed to?

Numbers and incidence rates are compiled for departments responsible for treatment (contact responsibility) and for the place of stay (address of stay).

• HOHA - infections are attributed to the department responsible for contact in the 48 hours leading up to sample time and the section where the patient was residing (address of stay) in the 48 hours before the sample was taken. HAIBA shows the infection at the time the sample was taken.
• COHA - the infection is attributed to the latest department that had contact responsibility and the latest section the patient stayed at.

When is a new infection registered?

An infection is considered new if it arises >= 60 days after a previous positive sample. If multiple control samples were analysed following an infection, positive results count as a new infection only if more than 60 days have passed since the previous positive sample.

How is incidence calculated?

Incidence is reported as the number of infections per 10,000 risk days:

• HOHA - risk days are defined as total hours of hospital contact. Hours after an infection arises or after patient death are excluded from the denominator.
• COHA - risk days are defined as the total number of hours in the period from 48 hours to 30 days after hospital contact. In cases where the patient has had multiple hospital contacts within 30 days of the first contact, the first 48 hours are included as risk days. No hours are included after infection or death occurs.