Repertoire of intensive care unit pneumonia microbiota

Area of Science:

• Microbiology
• Pulmonary Medicine
• Infectious Diseases

Background:

• The causative agents of pneumonia remain incompletely identified despite extensive research.
• Understanding the pulmonary microbiota is crucial for diagnosing and treating pneumonia.
• Intensive care unit (ICU) patients are particularly vulnerable to pneumonia.

Purpose of the Study:

• To comprehensively identify the microbiota in patients with various types of pneumonia in ICUs.
• To compare the pulmonary microbiota of pneumonia patients with that of non-pneumonia controls.
• To discover novel microbial species and phylotypes associated with pneumonia.

Main Methods:

• Collected bronchoalveolar lavage (BAL) samples from pneumonia patients (ventilator-associated, community-acquired, non-ventilator ICU, aspiration) and controls over three years.
• Utilized molecular techniques including 16S and 18S rDNA gene amplification, cloning, sequencing, and PCR for specific pathogen detection.
• Employed traditional methods such as culture, amoeba co-culture, antibody detection, and urinary antigen tests.

Main Results:

• Identified 160 bacterial species, including 73 previously unreported in pneumonia, and 37 putative new bacterial phylotypes.
• Detected 24 fungal species (6 new to pneumonia) and 7 viruses.
• Found a high diversity of microorganisms in BAL samples (mean 3.77 ± 2.93), with some common ICU pathogens present in controls, suggesting a core pulmonary microbiota.
• Observed distinct microbiota profiles across different pneumonia types.

Conclusions:

• Modern and traditional diagnostic techniques reveal a broader spectrum of microbial agents in pneumonia than previously recognized.
• The presence of typical ICU pathogens in controls indicates a baseline pulmonary microbiota that complicates etiological diagnosis.
• Further research into the complex pulmonary microbiome is warranted to improve pneumonia diagnostics and treatment strategies.