Hospital‑onset bacteraemia as a surveillance outcome

Ahead of next week’s Journal Club (which you can register for here) I have looked into the paper which Dr Beatriz Larru Martinez selected. The paper covers a large multicentre study, published in BMJ Quality & Safety, providing important evidence by examining the sources and perceived 'preventability' of hospital‑onset bloodstream infections.

Why consider hospital‑onset bacteraemia as an IPC outcome?

In the UK, surveillance focuses on a defined set of healthcare‑associated infections (HCAIs), including MRSA bacteraemia, selected Gram‑negative bloodstream infections, and specific device‑associated and surgical site infections. While valuable, these programmes capture only a proportion of bloodstream infections occurring during hospitalisation.

Hospital‑onset bacteraemia, pragmatically defined as a positive blood culture from day four of admission onwards, offers potential advantages as a complementary outcome, providing:

• objective identification using laboratory data
• higher event frequency than many mandatory indicators
• strong association with patient‑centred outcomes

The key question is whether such events represent modifiable harm or reflect intrinsic patient risk.

Study design and approach

The authors conducted a cross‑sectional review of 2,109 hospital‑onset bloodstream infection events across 13 hospitals, including adult and paediatric populations. Events were identified using a simple temporal definition rather than formal surveillance criteria. Source attribution was based on clinical adjudication rather than surveillance definitions, and preventability was assessed using a validated six‑point scale, with scores of 1–3 categorised as potentially preventable. This approach reflects the real‑world complexity faced by IPC teams.

Sources and preventability

Among events caused by pathogenic organisms, the most common sources were gastrointestinal and endovascular sources. Overall, 36% of non‑commensal events were rated potentially preventable. Preventability was higher for infections associated with intravascular catheters, urinary catheters, and surgical sites, and lower for events occurring in the context of neutropenia, long‑term immunosuppression, gastrointestinal translocation, polymicrobial infection, or prior bloodstream infection during the same admission.

Surveillance gaps and relevance to UK practice

Notably, around 40% of potentially preventable hospital‑onset bacteraemia events would not be detected by existing routine surveillance systems. This highlights a gap between current mandatory reporting and the broader burden of preventable bloodstream infection.

For NHS IPC teams, hospital‑onset bacteraemia surveillance could:

• complement existing HCAI reporting
• identify preventable harm outside standard definitions
• support locally driven quality improvement

However, the study also underscores the need for robust risk adjustment, particularly for immunosuppression and neutropenia, if hospital-onset bacteraemia is to be used meaningfully as a quality indicator.

Implications for IPC practice

For IPC teams, these findings reinforce the need to look beyond mandated HCAI metrics when assessing preventable harm. While device‑associated infections remain a key focus, hospital‑onset bacteraemia highlights a broader spectrum of bloodstream infection risk that is not routinely captured through existing surveillance. Used alongside current reporting frameworks, hospital-onset bacteraemia surveillance could support more comprehensive, risk‑informed review of bloodstream infections, help prioritise prevention efforts where modifiable factors are most likely, and provide additional insight into areas of harm that may otherwise remain invisible within standard IPC performance measures.

Conclusions

This study demonstrates that a substantial proportion of hospital‑onset bacteraemia is perceived as potentially preventable, with many events arising outside established surveillance frameworks. For the NHS, hospital-onset bacteraemia may be most useful as a supplementary IPC outcome, broadening visibility of preventable bloodstream infections while reinforcing the need for risk‑informed interpretation rather than simplistic performance judgement.