Throat microbiota drives alterations in pulmonary alveolar microbiota in patients with septic ARDS

Abstract

Objectives: The translocation of intestinal flora has been linked to the colonization of diverse and heavy lower respiratory flora in patients with septic ARDS, and is considered a critical prognostic factor for patients.

Methods: On the first and third days of ICU admission, BALF, throat swab, and anal swab were collected, resulting in a total of 288 samples. These samples were analyzed using 16S rRNA analysis and the traceability analysis of new generation technology.

Results: On the first day, among the top five microbiota species in abundance, four species were found to be identical in BALF and throat samples. Similarly, on the third day, three microbiota species were found to be identical in abundance in both BALF and throat samples. On the first day, 85.16% of microorganisms originated from the throat, 5.79% from the intestines, and 9.05% were unknown. On the third day, 83.52% of microorganisms came from the throat, 4.67% from the intestines, and 11.81% were unknown. Additionally, when regrouping the 46 patients, the results revealed a significant predominance of throat microorganisms in BALF on both the first and third day. Furthermore, as the disease progressed, the proportion of intestinal flora in BALF increased in patients with enterogenic ARDS.

Conclusions: In patients with septic ARDS, the main source of lung microbiota is primarily from the throat. Furthermore, the dynamic trend of the microbiota on the first and third day is essentially consistent.It is important to note that the origin of the intestinal flora does not exclude the possibility of its origin from the throat.

Keywords: 16S rRNA; ARDS; Sepsis; anal swab; bronchoalveolar lavage fluid; throat swab.

Figure 1.

Distribution of microbiota in the BALF, throat swab, and anal swab on day 1 and day 3 in patients with septic ARDS (a) The number of unique microbiota species in the throat swab on the first day and on the third day in patients with septic ARDS; (b) The number of unique microbiota species in the BALF on the first day and on the third day in patients with septic ARDS;C:The number of unique microbiota species in anal swab on the first day and on the third day in patients with septic ARDS;D:The number of unique microbiota for each group.

Figure 2.

Changes in the composition of the microbiota in the BALF, throat swab, and anal swab in patients with septic ARDS on the first and third days (a) Comparison of microbial richness in the BALF on the first and third day; (b) Comparison of microbial richness in the throat swabs on the first and third day; (c) Comparison of microbial richness in the anal swab on the first and third day; (d,e,f) PCoA analysis. The dots with different colours represent different sample groups. The closer the spatial distance of the sample is, the more similar the species composition structure of the sample is.

Figure 3.

Histogram of BALF throat swabs and anal swabs microbiota distribution in the survival group and the non-survival group on the first and third days. The abscissa represents the groupings, and the ordinate represents the gut microbiota abundance values. The taxa with an abundance above 1% were selected, and all abundances were in the top 15 for classification.

Figure 4.

Microbial relative abundance in BALF, throat swab and anal swab of patients with septic ARDS on the first and third day. Comparison of microbiota in different position of the two groups. The abscissa represents the abundance values, and the ordinate represents the bacterial groups. The Wilcoxon signed-rank sum test was used. (a) Comparison of microbiota between the first day and the third day in the BALF; (b) Comparison of microbiota between the first day and the third day in the anal swab; (c) Comparison of microbiota between the first day and the third day in the throat swab.

Figure 5.

Pie chart of SourceTracke analysis of BALF on day one and day three in patients with septic ARDS A: a new generation of traceability technology, and performed traceability analysis of the first day of BALF with the first day of throat swabs and anal swabs respectively in septic ARDS;B:a new generation of traceability technology, and performed traceability analysis of the first day of BALF with the first day of throat swabs and anal swabs respectively in septic ARDS.

Figure 6.

Pie chart of SourceTracke analysis of BALF on day one and day three in septic ARDS patients with enterogenic and non-enterogenic infection (a) A new generation of traceability technology, and performed traceability analysis of the first day of BALF with the first day of throat swabs and anal swabs respectively in septic ARDS patients with enterogenic infection; (b) A new generation of traceability technology, and performed traceability analysis of the third day of BALF with the third day of throat swabs and anal swabs respectively in septic ARDS patients with enterogenic infection; (c) A new generation of traceability technology, and performed traceability analysis of the first day of BALF with the first day of throat swabs and anal swabs respectively in septic ARDS patients without enterogenic infection; (d) A new generation of traceability technology, and performed traceability analysis of the third day of BALF with the third day of throat swabs and anal swabs respectively in septic ARDS patients without enterogenic infection.