Broad-spectrum empirical antibiotic overuse in community-onset bacteraemia: Prevalence, outcomes, and associated...

Empirical broad-spectrum antibiotic overuse in community-onset (CO) bacteraemia poses significant clinical risks. We evaluated the prevalence and risk factors of excessively broad-spectrum empirical antibiotic use and its association with clinical outcomes.

This retrospective cohort study included 11 183 inpatients diagnosed with CO bacteraemia. CO bacteraemia was further classified as community-acquired (CA) bacteraemia or healthcare-associated (HCA) bacteraemia. Excessively broad-spectrum antibiotic use was defined as empirical broad-spectrum antibiotic administration without isolating a compatible resistant pathogen, and clinical characteristics and outcomes were compared according to that status using inverse probability of treatment weighting-adjusted logistic regression.

Among all eligible patients, adequate empirical antibiotics were administered to 9343 (83.5%) patients; however, 6944 (62.1%) were administered excessively broad empirical antibiotics - 4040 (63.5%) among HCA patients and 2904 (60.2%) among CA patients. Despite high rate of broad-spectrum empirical antibiotics prescribing (69.9% of CA patients and 81.5% of HCA patients), resistant organisms were microbiologically confirmed in only 24.1% of CA patients and 43.1% of HCA patients. Cancer, higher Pitt bacteraemia scores, and inotropics use were independently associated with excessively broad-spectrum empirical antibiotic administration. Infection sources were also associated with prescribing patterns, and broad-spectrum antibiotic use was more likely in lower respiratory tract and intra-abdominal infections. Excessive use was associated with adverse outcomes, including in-hospital mortality (adjusted odds ratio 1.57; 95% confidence interval, 1.16-2.11) and Clostridioides difficile infection (adjusted odds ratio 1.72; 95% confidence interval, 1.08-2.74).

Excessively broad empirical antibiotic use was prevalent and associated with adverse clinical outcomes in CO bacteraemia, underscoring the need for enhanced antimicrobial stewardship.