3.3 Stratification by origin of infection

When generating data and estimating the proportion and frequency of AMR infections, it is important to stratify the data by origin of infection and to estimate the burden accordingly.

Commonly used categories for origin of infection

There are three categories that are commonly used to stratify data by origin of infection:

• community-origin
• healthcare-associated
• hospital-origin.

The proportion and frequency of AMR infections across these three categories could be very different as patient characteristics and the risk of exposure to AMR pathogens are different.

Community-origin infections have been defined as the isolation of a pathogenic organism from a clinical sample taken within the first two days of hospitalisation and without history of a hospital stay in the 30 days prior to the hospitalisation, or taken from individuals who have signs of infection but do not need hospitalisation (e.g. uncomplicated UTI treated as an outpatient) and without a history of hospital stay in the 30 days prior to the current presentation.

Healthcare-associated infections have been defined as the isolation of a pathogenic organism from a clinical sample taken in the first two days of hospitalisation and with a history of a hospital stay or healthcare interaction within 30 days prior to the hospitalisation.

Hospital-origin infections have been defined as the isolation of a pathogenic organism from a clinical sample taken after the first two days of hospitalisation.

Further details on the classifications and their definition can be found in the article ‘Epidemiology and clinical features of community-acquired, healthcare-associated and nosocomial bloodstream infections in tertiary-care and community hospitals’ [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] (Rodríguez-Baño et al., 2010).

GLASS categories for origin of infection

The World Health Organization (WHO) Global Antimicrobial Resistance and Use Surveillance System (GLASS) (WHO, 2017) defines two types of infection origin as below:

• Community-origin: Patients cared for at outpatient clinics or patients in hospital for two calendar days or fewer when the specimen was taken. Specimens collected from patients in the community or in hospital on the first or second day are considered a proxy for community infections.
• Hospital-origin: Patient admitted for more than two calendar days when the specimen was taken or admitted to the healthcare facility for less than two calendar days but transferred from another healthcare facility where he or she was admitted for two or more calendar days. Specimens collected from hospital patients in hospital on the third day or later are used as a proxy for hospital-origin infections.