Nasal swab-guided deescalation of empirical linezolid in respiratory infections at a secondary-level hospital: quantification of quality gaps and antimicrobial stewardship opportunities.

backgroundEmpirical linezolid for respiratory infections risks overtreatment and therapeutic inertia. Methicillin-resistant

methodsA retrospective observational study of 83 patients receiving empirical linezolid for respiratory infections at a secondary-level hospital during five non-consecutive months of 2025. Three quality gaps were defined: Gap 0 (initiation without MRSA risk criteria); Gap 1 (failure to request a nasal swab in eligible patients); and Gap 2 (therapeutic inertia following a negative result).

resultsGap 0 affected 30.1% of patients, predominantly CAP (72%), discontinuation was more frequent in Gap 0 patients than in eligible candidates. Gap 1 affected 32.5%, with marked inter-unit variability: swabs were requested in 78% of Internal Medicine patients versus 41.7% in Respiratory Medicine. Among 56 patients with results, 85.7% were negative; Gap 2 affected 20.8%, generating 56 days of linezolid administered after a negative result was available. Patients with positive swabs had significantly higher cumulative risk scores than negative patients. Overall, 62.7% of patients presented ≥1 gap, accounting for 69.5% of 377 total linezolid-days.

conclusionsQuality gaps in empirical linezolid use affect two-thirds of patients and are associated with nearly 70% of treatment days. Targeted two-level ASP interventions, explicit indication criteria, and systematic de-escalation prompts after negative swabs are warranted.