The contamination of ventilator circuits poses a significant infection risk in mechanically ventilated patients. Ventilator-associated pneumonia (VAP), which develops after more than 48 h of mechanical ventilation, remains a major clinical concern. This study aimed to evaluate a newly developed test lung that incorporates a hydrophobic membrane designed to prevent contamination and transmission of VAP-related bacteria.

Five bacterial species identified by the Japanese Respiratory Society as major VAP pathogens - Staphylococcus aureus JCM20624, Pseudomonas aeruginosa JCM5962, Klebsiella pneumoniae JCM1662, Stenotrophomonas maltophilia JCM1975, and Enterobacter cloacae JCM1232 - were introduced into a catheter mount connected to either a conventional or the novel test lung. The ventilator circuits were run for 30 min, and the test lungs were examined for the presence of bacteria using colony counting and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS).

All five bacterial species were recovered and correctly identified in the conventional test lungs. In contrast, no bacterial colonies were detected in any of the novel test lungs.

This novel lung test effectively prevented the entry of all five VAP-causing bacteria. This structural improvement may reduce ventilator circuit contamination, simplify sterilization procedures, and alleviate the workload on healthcare workers, especially in home care settings.