Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:has been reported as one of the most common pathogens that cause hospital-acquired bloodstream infections in patients undergoing surgical or chemotherapeutic interventions and/or with underlying immunological deficiencies (Wisplinghoff et al., 2004; Pfaller & Diekema, 2007).
Category: