The purpose of this study is to investigate whether chlorhexidine mouthrinse is effective in preventing microbial contamination during endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA).

EBUS-TBNA using the convex probe is a standard of care for the assessment of mediastinal and hilar lymphadenopathy. Although EBUS-TBNA is a minimally invasive procedure, rare but serious infectious complications such as pneumonia, lung abscess, empyema, mediastinal adenitis/abscess, mediastinitis, pericarditis, and sepsis were reported. EBUS-scope might be contaminated with oropharyngeal commensal bacteria while passing the oropharyngeal airway during EBUS-TBNA. Contamination of punctured lymph nodes by oropharyngeal commensal bacteria can cause severe infections.

Chlorhexidine gluconate is an antimicrobial agent that has a broad antibacterial activity including both gram-positive and negative bacteria. Chlorhexidine has been widely used for surgical scrub, skin disinfection, and mouthrinse. We, therefore, designed a phase 4, single-center, randomized, controlled clinical trial to investigate whether chlorhexidine mouthrinse is effective in preventing microbial contamination during EBUS-TBNA.

Inclusion Criteria:

• inpatients aged 19 years and older who are scheduled to undergo EBUS-TBNA using a convex probe

Exclusion Criteria:

• antiseptic mouthrinse within 7 days before inclusion;
• active infection or antibiotic treatment within 7 days before inclusion;
• immunocompromised;
• trachemostomy status;
• who have already undergone gastroscopy on the same day when EBUS- TBNA is scheduled to be administered