Effectiveness of Oral Prophylactic Antibiotics for Diagnostic Bronchoscopy: A Nationwide Database Study

Rationale: Although guidelines generally omit routine antibiotic prophylaxis for diagnostic bronchoscopy, this recommendation is based primarily on studies with relatively small sample sizes conducted at single institutions. Moreover, the applicability of recent technical and procedural advances to these guidelines remains uncertain. Objectives: To evaluate whether oral prophylactic antibiotic administration for diagnostic bronchoscopy reduces postbronchoscopy infections among noninfectious diseases in the current setting. Methods: Using the Diagnosis Procedure Combination database, a national inpatient database in Japan, we identified patients who underwent diagnostic bronchoscopy with or without oral prophylactic antibiotics between April 2020 and March 2022. We used propensity score-stabilized inverse probability of treatment weighting and instrumental variable analyses to compare postbronchoscopy infections between the groups. Stratified analyses were also conducted on the basis of patient profiles and antibiotic types. Results: A total of 68,660 eligible patients were divided into prophylaxis (n = 10,426) and no-prophylaxis (n = 58,234) groups. Post-bronchoscopy infections were observed in 612 patients (0.89%). The stabilized inverse probability of treatment weighting analysis showed that the prophylactic group was significantly associated with a decrease in postbronchoscopy infections (odds ratio, 0.60; 95% confidence interval, 0.45-0.80). The instrumental variable analysis showed similar results (odds ratio, 0.50; 95% confidence interval, 0.34-0.74). Oral antibiotic prophylaxis was associated with reduction in postbronchoscopy infection in patients who were older than 70 years, underwent bronchoscopy for malignancy, underwent biopsy or bronchoalveolar lavage, or received aminopenicillin or fluoroquinolone for prophylaxis. Conclusions: Our findings suggest a potential role for prophylactic antibiotics in reducing postbronchoscopy infections among noninfectious patients. Although prophylactic antibiotics may help prevent these infections, their use should be carefully considered in relation to individual patient profiles and the specific antibiotics being administered.