Pleural infection, encompassing both empyema (frank pus in the pleural space) and complicated parapneumonic effusion, represents a serious and potentially life-threatening infectious condition that continues to pose significant challenges for clinicians worldwide. Despite advances in antimicrobial therapy, diagnostic techniques, and interventional procedures, pleural infection remains associated with substantial morbidity, prolonged hospital stays, increased healthcare costs, and significant mortality, particularly in elderly and immunocompromised patients. The clinical management requires prompt recognition, appropriate antimicrobial therapy, and effective drainage of infected pleural fluid, yet delays in diagnosis and inappropriate initial antibiotic selection remain common.
A critical aspect of managing pleural infection is understanding differences between hospital-acquired (HAPI) and community-acquired (CAPI) forms, as these two entities differ fundamentally in etiology, microbiology, antimicrobial resistance patterns, and patient populations, with important implications for empirical treatment selection and infection control. However, comprehensive data comparing HAPI and CAPI, particularly from large patient cohorts, have remained limited. This retrospective study, conducted over an 11-year period at the First Medical Centre of Chinese PLA General Hospital in Beijing, represents one of the largest single-center cohorts of pleural infection patients reported to date, encompassing 832 patients with confirmed pleural infection. The study's primary objective was to systematically describe and compare clinical characteristics, etiological factors, microbiological profiles, antimicrobial resistance patterns, predisposing factors, and clinical outcomes associated with HAPI and CAPI in a large Chinese patient population.
The findings revealed that HAPI accounted for the overwhelming majority of cases (84.9%), while CAPI represented only 15.1%, a distribution reflecting the increasingly hospital-centric nature of serious infections in modern healthcare settings, particularly in large tertiary-care hospitals managing complex and critically ill patient populations. This predominance of HAPI has important implications for healthcare systems, as hospital-acquired infections are generally associated with more resistant pathogens, higher treatment costs, and poorer outcomes. The etiological profiles of HAPI and CAPI differed significantly. For community-acquired pleural infection, the most common underlying cause was pneumonia and pleurisy, consistent with typical pathogenesis where infection spreads from lung parenchyma to the pleural space. In contrast, the most common cause of hospital-acquired pleural infection was trauma or chest surgery, reflecting the iatrogenic nature of many HAPI cases where surgical procedures, chest tube placement, or traumatic injuries breach normal anatomical barriers and introduce pathogens. The study also identified significant differences in predisposing factors. Factors significantly more prevalent in HAPI included abdominal indwelling catheter, thoracic cavity drainage for 10 or more days, and broad-spectrum antibiotic use, all well-established risk factors for healthcare-associated infections.
These findings highlight the importance of minimizing unnecessary invasive procedures, removing indwelling catheters and drains as soon as clinically feasible, and practicing antimicrobial stewardship to reduce HAPI risk. Other predisposing factors including central intravenous catheter, indwelling urinary catheterization, invasive mechanical ventilation, ICU admission, hemodialysis, chemoradiotherapy, and parenteral nutrition were common but did not show statistically significant differences between HAPI and CAPI. Microbiological analysis revealed distinct pathogen profiles between HAPI and CAPI. Among Gram-positive bacteria, Staphylococcus epidermidis was the most frequently isolated pathogen in HAPI (24.76%), while Streptococcus species predominated in CAPI (27.00%), reflecting different sources of infection: coagulase-negative staphylococci are common skin flora and frequent causes of healthcare-associated infections, while Streptococcus species are common respiratory pathogens and typical causes of community-acquired pneumonia. Among Gram-negative bacteria, Acinetobacter baumannii was the most common pathogen in HAPI (8.61%), while Escherichia coli predominated in CAPI (4.38%). The antimicrobial resistance data were particularly concerning. Virtually all Gram-positive bacteria were susceptible to linezolid and vancomycin, except for Enterococcus faecium which displayed vancomycin resistance at 9.88%. Among Gram-negative organisms, Acinetobacter baumannii demonstrated alarmingly high resistance rates (exceeding 60%) to most antibiotics including carbapenems, while Klebsiella pneumoniae and Pseudomonas aeruginosa also showed high levels of resistance.
These high resistance rates underscore the critical importance of obtaining timely culture and susceptibility data and adjusting antibiotic therapy accordingly. The overall 30-day mortality after onset of pleural infection was 13.1%, significantly higher than reported in many other studies (approaching 4%), likely reflecting severity of illness and high prevalence of comorbidities in this tertiary-care hospital population. Notably, no statistically significant difference in mortality was observed between CAPI (11.9%) and HAPI (13.3%), which may seem surprising given typically more resistant pathogens and more comorbid patient population associated with HAPI. The authors suggest this may be attributable to relatively low proportion of HAPI caused by pneumonia, high proportion caused by surgery and tumor (which may have lower mortality due to multidrug-resistant bacterial infection), and more aggressive use of combination antibiotic therapy in HAPI patients.
