Microbiological Profile of Patients with Aspiration Pneumonia Identified by Combined Detection Methods

Abstract

Purpose: Aspiration pneumonia (AP) challenges public health globally. The primary aim of this study was to ascertain the microbiological profile characteristics of patients with AP evaluated by combined detection methods, including conventional microbiological tests (CMTs), chips for complicated infection detection (CCID), and metagenomic next-generation sequencing (mNGS).

Patients and methods: From June 2021 to March 2022, a total of thirty-nine patients with AP or community-acquired pneumonia with aspiration risk factors (AspRF-CAP) from 3 hospitals were included. Respiratory specimens, including bronchoalveolar lavage fluid (BALF), sputum, and tracheal aspirate, were collected for microorganism detection.

Results: Patients with AP were more inclined to be older, to have a shorter duration from illness onset to admission, to have a higher prevalence of different underlying diseases, particularly diabetes mellitus, chronic heart disease, and cerebrovascular disease, and to have a higher CURB-65 score (all P < 0.05). A total of 213 and 31 strains of microorganisms were detected in patients with AP and AspRF-CAP, respectively. The most common pathogens in AP were Corynebacterium striatum (17/213, 7.98%), Pseudomonas aeruginosa (15/213, 7.04%), Klebsiella pneumoniae (15/213, 7.04%), and Candida albicans (14/213, 6.57%). Besides, the most common pathogens in AspRF-CAP were Candida albicans (5/31, 16.13%), Pseudomonas aeruginosa (3/31, 9.68%) and Klebsiella pneumoniae (3/31, 9.68%). Moreover, Klebsiella pneumoniae (7/67, 10.45%) and Candida glabrata (5/67, 7.46%) were the most common pathogens among the 9 non-survived patients with AP.

Conclusion: The prevalent pathogens detected in cases of AP were Corynebacterium striatum, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Candida albicans. Early combined detection methods for patients with AP enhance the positive detection rate of pathogens and potentially expedites the initiation of appropriate antibiotic therapeutic strategies.

Keywords: aspiration; chips; combined detection; metagenomic next-generation sequencing; microbiology; pneumonia.

Figure 1

Flowchart of the participants included in the present study.

Figure 2

Microorganisms detected in patients with AP and AspRF-CAP. The column chart showed the numbers of microorganisms detected. A total of 213 and 31 strains of microorganisms were detected in patients with AP and AspRF-CAP, respectively. The left pie chart showed the detailed proportions of microorganism distribution in AP patients, including bacterial pathogen only (1/28, 3.57%), bacteria-fungi co-detection (13/28, 46.43%), bacteria-virus co-detection (1/28, 3.57%), and bacteria-fungi-virus co-detection (13/28, 46.43%). The right pie chart showed the detailed proportions of microorganism distribution in AspRF-CAP patients, including not detected (1/11, 9.09%), fungal pathogen only (1/11, 9.09%), bacteria-bacteria co-detection (1/11, 9.09%), fungi-fungi co-detection (1/11, 9.09%), bacteria-fungi co-detection (3/11, 27.28%), and bacteria-virus co-detection (4/11, 36.36%).

Figure 3

Comparison and overlap of isolated microorganisms between severe AP and non-severe AP. The column chart showed the numbers of microorganisms detected. A total of 123 and 90 strains of microorganisms were detected in 16 severe AP cases and 12 non-severe AP cases, respectively. The left pie chart showed the detailed proportions of microorganism distribution in severe AP patients, including bacteria-fungi co-detection (9/16, 56.25%) and bacteria-fungi-virus co-detection (7/16, 43.75%). The right pie chart showed the detailed proportions of microorganism distribution in non-severe AP patients, including bacterial pathogen only (1/12, 8.33%), bacteria-virus co-detection (1/12, 8.33%), bacteria-fungi co-detection (4/12, 33.33%), and bacteria-fungi-virus co-detection (6/12, 50.00%).

Figure 4

Microorganisms detected in non-survived patients. Klebsiella pneumoniae and Candida glabrata were the most common pathogens among the 9 non-survived AP patients, whereas Corynebacterium striatum and Candida glabrata were the most common pathogens in 2 non-survived AspRF-CAP patients.

Figure 5

Comparison of diagnostic performance. (A) The positive rate of pathogen in BALF was significantly higher than that of sputum samples (97.4% vs 70.0%, P = 0.002). (B) The positive rate of pathogen with consistent BALF samples. The positive rate of mNGS was significantly higher than that of CMTs (88.0% vs 80.0%, P = 0.004). (C) Venn diagrams for specific pathogens detected according to different detected methods. Pink for mNGS. Blue for CCID. Cyan for CMTs. The numbers in the circles stand for cases.