# Predictors of osteo-articular infection in Staphylococcus aureus bacteremia in a tertiary center between 2017 and 2022

## TL;DR

This study finds that nearly one-third of patients with Staphylococcus aureus bloodstream infections also have osteo-articular infections, especially those with community-acquired infections or longer illness duration.

## Contribution

The study identifies community-acquired bacteremia and prolonged bacteremia duration as novel predictors of osteo-articular infection in Staphylococcus aureus bloodstream infections.

## Key findings

- Osteo-articular infection occurred in 28.8% of Staphylococcus aureus bacteremia patients.
- Community-acquired bacteremia and longer duration of bacteremia were significant risk factors for osteo-articular infection.
- Active cancer and ICU admission were associated with a lower likelihood of osteo-articular infection.

## Abstract

Introduction: Among bloodstream infections, Staphylococcus aureus bacteremia (SAB) is associated with a particularly high mortality rate, which may be higher in patients with undiagnosed metastatic infections. The primary objective of the present study was to identify risk factors for osteo-articular infection (OAI) in patients with active SAB. Methods: A retrospective study was conducted in a single-center tertiary-care hospital in Brussels, Belgium. Data were collected on patients diagnosed with SAB between 2017 and 2022. Results: Among the 489 consecutive patients with SAB included in this study, 141 (28.8 %) had a concomitant osteo-articular infection (OAI), accounting for nearly one in three patients. These infections included osteomyelitis (12.7 %), native joint septic arthritis (NJSA) (8.8 %), spondylodiscitis (8.4 %), and prosthetic joint infection (PJI) (3.9 %). Univariate and multivariate analyses were performed to identify risk factors associated with OAI. The duration of bacteremia (OR (odds ratio): 1.27, 95 %, CI (confidence interval): 1.14–1.42,
p<0.001
) and community-acquired bacteremia (OR: 3.23, 95 % CI: 1.85–5.88,
p<0.001
) were associated with the occurrence of OAI. The presence of active cancer (OR: 0.14, 95 % CI: 0.06–0.31,
p<0.001
) and intensive care unit (ICU) admissions for SAB (OR: 0.31, 95 % CI: 0.17–0.56,
p<0.001
) were associated with a lower likelihood of OAI. Conclusion: In this cohort, OAI was very frequent during SAB and occurred in 28.8 %, particularly in patients with community-acquired SAB (CA-SAB) or those with a longer duration of bacteremia. These findings highlight the importance of a comprehensive diagnostic evaluation for both primary and secondary infection foci, such as OAI, in the setting of SAB.