Characterising health care-associated bloodstream infections in public hospitals in Queensland, 2008–2012

Si and colleagues1 are commended for reporting on the bloodstream infection (BSI) surveillance in 23 Queensland public hospitals via the Centre for Healthcare Related Infection Surveillance and Prevention (2008–2012). Bloodstream infections are significant in terms of the need for intravenous antibiotics and hospitalisation, and estimating the burden of illness can reflect emerging trends. However, our experience of targeted BSI monitoring in Victorian hospitals indicates that health care-associated infection surveillance should also provide meaningful data to inform prevention programs. We note that Si and colleagues reported some data that appear reliant on non-standardised surveillance methodology, and some measures that may not facilitate action at the hospital level.

First, the inclusion of common skin commensals identified in a single blood culture, even in a patient commenced on empirical antibiotics, can be problematical. Such events are unlikely to represent a true infection and will comprise a significant portion of all observed pathogens.2 Inclusion of these infections will, therefore, affect the reported relative incidence of other more pathogenic organisms.

Second, we note that catheter tip cultures were employed as one method for defining device-associated BSIs. These are variably requested at the discretion of health care providers for clinical diagnosis, together with other tests such as differential time to positivity of central versus peripheral blood cultures. In contrast, standardised surveillance criteria are required for device-associated infections3 to ensure reliability and reproducibility of data. Estimates of disease burden are therefore not comparable with other programs, and inferences regarding ward or site of infection should be interpreted cautiously.

We also question the value of data concerning neutropenic patients with gram-negative BSIs. In the setting of chemotherapy-induced mucositis, such infections may arise in both community and inpatient settings, do not reflect breeches in aseptic technique or best clinical practice, and are not amendable to prevention activities.4 More likely, these infections reflect the intensity of cancer therapies and presence of comorbidities in cancer populations.

Quality improvement programs in health care must focus on modifiable factors and systems to mitigate risk, and should be underpinned by reliable, reproducible and valid data.5 We believe that the reported data are valuable, but suggest that additional clinical and epidemiological elements and standardised methodology would enhance the strategy.