Phenotyping empyema by pleural fluid culture results and macroscopic appearance: an 8-year retrospective study

Abstract

BackgroundThe understanding on the clinical impact of phenotyping empyema is limited. The study was designed to evaluate the clinical characteristics and outcomes based on the two readily available parameters, pleural fluid culture status and macroscopic fluid appearance.MethodsA retrospective study was conducted on patients with empyema hospitalised between 2013 and 2020. Empyema was classified into culture-positive empyema (CPE) and culture-negative empyema (CNE); pus-appearing empyema (PAE) and non-pus-appearing empyema (non-PAE) based on the pleural fluid culture status and macroscopic fluid appearance respectively.ResultsAltogether 212 patients had confirmed empyema (CPE: 188, CNE: 24; PAE: 118, non-PAE: 94). The cohort was male predominant (163, 76.9%) with a mean age of 65.0±13.6 years. Most patients (180, 84.9%) had at least one comorbidity. Patients with CPE had higher in-hospital (19.1%versus0.0%, p=0.017), 90-day mortality rates (18.6%versus0.0%, p=0.017) and more extra-pulmonary sources of infection (29.8%versus8.3%, p=0.026) when compared with patients with CNE. No significant difference in mortality rate was found between PAE and non-PAE during the in-hospital stay, 30 days and 90 days. Patients with PAE had less extra-pulmonary source of infection (20.3%versus36.2%, p=0.010) and more anaerobic infection (40.9%versus24.5%, p=0.017) than those with non-PAE. The median RAPID scores were higher in the CPE and non-PAE groups. After adjusting for covariates, culture positivity was not independently associated with mortality on multivariable analysis.ConclusionEmpyema is a heterogeneous disease with different clinical characteristics. Phenotyping empyema into different subclasses based on pleural fluid microbiological results and macroscopic fluid appearance would provide insight on the underlying bacteriology, source of infection and subsequent clinical outcomes.

Tuberculous pleuritis: clinical presentations and diagnostic challenges

“…Different cut-off levels have been described [61], which can be affected by the commercial kit used, and patient factors (age [62,63] or comorbid illnesses [41,64,65]). Raised pleural fluid ADA levels can be found in non-TBP conditions, including occasional cancers, rheumatological conditions and many cases of pleural infection [35][36][37]66]. Bacterial empyema often generates very high ADA levels (e.g.…”

“…Bacterial empyema often generates very high ADA levels (e.g. > 100 U/l) [ 66 ]. In endemic countries, raised pleural fluid ADA level is often considered confirmatory for TBP in patients with a consistent clinical picture of TB.…”

Infective Pleural Effusions—A Comprehensive Narrative Review Article

“…The yield from standard pleural culture was only 56% in a recently published systemic review of over 10,000 patients; however, rates improve when fluid is inoculated into blood culture bottles [ 20 ]. Culture positivity was not independently associated with mortality [ 36 ]. Medical thoracoscopy remains the gold standard modality of diagnosis, enabling direct visual sampling.…”