Abstract Introduction Endotracheal tubes (ETTs) can be colonized by pathogenic bacteria and serve as reservoirs for infection. ETTs are also inoculated by direct contact with environmental reservoirs. Culture-independent methods can detect pathogenic microbes that are not identified by routine microbiological cultures. We identified microbial populations on ETTs through taxonomic profiling based on 16S rRNA gene analysis after short-term use in mechanically ventilated patients. Methods This IRB-approved, prospective, cross-sectional pilot study was conducted among mechanically-ventilated adult ICU patients at the University of Tennessee Medical Centre. ETTs were collected using aseptic techniques. Tracheal aspirates and environmental samples (airborne sources and surfaces) were collected. For surfaces, polyester-tipped swabs pre-moistened with sterile PBS-tween solution, moved back and forth to cover a 2. 25-dm2 surface area, were employed. Glass microfiber filters (1. 5 µ pore size) fitted to an air sampler for 30 min at 10 ml/min air flow rate collected airborne microbial contaminants. Microbial biomass was extracted by vortexing in PBS. The species identification was accomplished via DNA extraction, PCR amplification, and high-throughput sequencing of the 16S rRNA gene (V4 region) amplicon libraries. Sequencing data were processed and interpreted using the QIIME software tool for statistical analysis and taxonomy classification. Results Four patients (2 males) aged 47- 90 years received mechanical ventilation for 1-4 days. Only one patient had a positive tracheal aspirate culture (Bacillus sp). Three patients had received Vancomycin; none received corticosteroids. The microbial population on ETTs, showed significantly greater bacterial diversity and richness (measured by Chao1, observed species, Shannon, Simpson indices) compared to air and surface samples. Firmicutes (47. 5%) dominated ETTs at the phylum level, followed closely by Bacteroidota (18. 3%), Actinobacteriota (17. 3%), and Fusobacteriota (10. 8%). In genus-level profiles, we found high abundances of Streptococcus (17. 8%), Prevotella₇ (12. 3%), Rothia (11. 5%), and Veillonella (11. 3%) (Figure1). Air and surface samples included more opportunistic taxa such as Acinetobacter, Ralstonia, and Pseudomonas. The human lung microbiome was the primary source of the ETT microbiome, followed by the surface microbiome, unknown source third, and air fourth. Contributions from the human gut and skin microbiota were minor. Conclusion In the first few days of mechanical ventilation, the ETT microbial population was predominantly patient-derived, with contributions from other organisms, such as Acinetobacter and Pseudomonas, found in environmental surface and air samples. Identifying specific microbial communities on ETTs and their sources could enhance infection prevention and control strategies for intubated, mechanically ventilated patients. This abstract is funded by: None
Nadkarni et al. (Fri,) studied this question.