Microbiological Concordance of Subglottic Secretion and Tracheal Aspirate Cultures of Critically Ill Patients with Invasive Airway Devices: A Prospective Observational Study

Background: Development of ventilator-associated pneumonia (VAP) is attributed to the microaspiration of pooled secretions around the cuff of airway devices. Despite the emphasis on the use of endotracheal tubes (ET) with subglottic secretion (SS) drainage ports to prevent VAP, the quality of the evidence for this recommendation remains moderate. This prospective observational study analyzed microbiological concordance between SS and endotracheal aspirate (ETA) cultures to generate further evidence in this regard.

Materials and methods: Paired samples (SS and ETA) of 100 consenting patients admitted to intensive care unit (ICU) were sent on day 1, 4, and 7 to the microbiology laboratory where they were transcultured and species identification was performed. The SS and ETA were considered concordant or discordant based on isolated organisms and antibiotic sensitivity profile. Clinical surveillance for VAP was done according to CDC criteria during the first week of ventilation.

Results: For a total of 197 paired samples, the overall concordance of SS and ETA cultures was 71.5%, with day-wise concordances of 68, 76.2, and 73.5% for D1, D4, and D7, respectively. Gram-negatives bacteria were the most frequently isolated, with 125 (31.7%) samples reporting A. baumannii. Amongst 18 patients clinically diagnosed with VAP during the first week of MV, the concordance between SS and ETA was 73.5%, and day-wise concordance was 77.2, 72.2, and 76.9% on D1, D4, and D7, respectively.

Conclusion: A fairly high microbiological concordance was observed in SS and ETA samples obtained from patients with invasive airway devices, and similar concordance was found in patients developing VAP during the first week of ventilation.

How to cite this article: Panigrahi P, Ganesh V, Angrup A, Sahni N, Biswal M, Yaddanapudi L. Microbiological Concordance of Subglottic Secretion and Tracheal Aspirate Cultures of Critically Ill Patients with Invasive Airway Devices: A Prospective Observational Study. Indian J Crit Care Med 2024;28(12):1139-1146.