Microbial Colonization and Potential Bacterial Translocation of High-Flow Nasal Cannula Circuits During Prolonged Use in Elderly Hospitalized Patients: A Prospective Observational Study

Background: High-flow nasal cannula (HFNC) oxygen therapy provides effective respiratory support with enhanced comfort and airway humidification. Long-term use of HFNC is increasingly adopted in respiratory oxygen therapy for elderly patients, yet Catheter-related bacterial translocation and colonization risks remain unstudied. Methods: This prospective study enrolled 102 elderly hospitalized patients (mean age: 94.2 ± 5.1 years old) receiving HFNC therapy. Microbial samples were collected from the HFNC circuits and analyzed to assess respiratory circuit colonization. The optimal tubing replacement interval was determined through ROC curve analysis. Additionally, for one patient who developed pulmonary infection after receiving HFNC, microbial homology was evaluated between microorganisms cultured isolates from the lower respiratory tract and those from the HFNC tubing using whole-genome sequencing and antibiotic resistance gene profiling. Results: Microbial colonization of HFNC tubing was detected in 56.9% (58/102) of patients, with prevalent pathogens including Filamentous fungi (25.9%), Methicillin-resistant Staphylococcus aureus (20.7%), and Streptococcus spp . (13.8%). The median time to tubing colonization was 136.2 ± 58.2 days. Pulmonary infections occurred significantly more frequently in the culture-positive group (37/58=63.8%) compared to the culture-negative group (17/44=38.6%; P = 0.016). ROC analysis identified 90.5 days as the study-specific optimal cutoff associated with tubing contamination. In the case study, Pseudomonas aeruginosa was isolated from both the patient’s lower respiratory tract and HFNC tubing. Homology analysis confirmed the strains were identical ( ST2069, O6 serotype ) and harbored six shared resistance genes (aph(3′)-IIb, crpP, catB7, blaPAO, blaOXA-488, fosA). Conclusion: Prolonged HFNC use was associated with substantial microbial colonization of the circuit in elderly hospitalized patients. Replacing HFNC tubing at approximately 90-day intervals may reduce microbial colonization and pneumonia risk in elderly patients during HFNC therapy. The HFNC tube circuit serves as a potential reservoir for pathogenic translocation, highlighting the importance of timely tubing replacement and microbial monitoring of the tube in infection prevention protocols.