Heterogeneity in clinical patterns of adult lung abscess patients: an 8-year retrospective study in a tertiary hospital.

backgroundThe widespread use of broad-spectrum antibiotics has led to changes in both the microbiological and clinical characteristics of lung abscesses. It is necessary to re-evaluate the bacterial spectrum associated with these infections. As a novel method for pathogen detection, metagenomic next-generation sequencing (mNGS) is increasingly being applied in clinical practice. There is limited research evaluating the use of mNGS in patients with lung abscesses.

methodsA retrospective analysis was conducted on patients with lung abscess who were hospitalized between July 2015 and July 2023 at a teaching hospital in China. Patients who underwent both computerized tomography (CT) imaging and conventional pathogen testing were included in the study. The efficacy of pathogen detection using conventional methods was compared with that of mNGS. Additionally, the clinical and radiological features were analyzed to provide a comprehensive understanding of the disease patterns.

resultsA total of 782 patients with lung abscess were included in the study and hematogenous abscess accounting for 7.16% (56/782) of cases. The overall hospital mortality rate was 1.53%. The mean age of the patients with lung abscess was 60 years, with a male predominance (80.2%). A significant proportion of patients had comorbid conditions, including diabetes (29.7%) and cardiovascular disease (18.2%). Lung abscesses were predominantly located in the right lung, and pleural effusion was more commonly observed in the deceased group. The detection rate of pathogen via conventional test was lower at 41.8% (327/782). Among patients with positive mNGS results, only 51.9% had pathogens identified through conventional testing methods. Klebsiella pneumoniae was the most frequently detected pathogen by conventional culture, while mNGS identified was Parvimonas micra. Infections caused solely by anaerobic bacteria or facultative anaerobes were associated with shorter hospital stays. Patient infected with Gram-negative bacilli (GNB) had a higher proportion of liver abscesses (11.8%).

conclusionCompared to conventional testing methods, mNGS demonstrates superior performance in detecting anaerobic and facultative anaerobic bacteria. The low detection rate of conventional tests may result in an underestimation of the clinical significance of anaerobic bacteria infections. In patients with lung abscess caused by GNB, hematogenous dissemination, liver abscess and diabetes were more commonly observed and these patients tended to have longer hospital stays.