Bacteriology and clinical outcomes of patients with culture-positive pleural infection in Western Australia: A 6-year analysis

Background and objective: Pleural infection is a clinical challenge; its microbiology can be complex. Epidemiological and outcome data of pleural infection in adult Australians are lacking. We describe the bacteriology and clinical outcomes of Australian adults with culture-positive pleural infection (CPPI) over a 6-year period. Methods: Cases with CPPI were identified through Western Australian public hospitals electronic record. Culture isolates, admission dates, vital status, co-morbidities, radiology, blood and pleural fluid tests were extracted. Results: In total, 601 cases (71.4% males; median age: 63 years (IQR: 50–74); median hospital stay 13 days) involving 894 bacterial isolates were identified. Hospital-acquired (HA)-CPPI was defined in 398 (66.2%) cases, community-acquired (CA)-CPPI in 164 (27.3%) cases and the remaining classified as oesophageal rupture/leak. Co-morbidities, most frequently cancer, were common (65.2%). Radiological evidence of pneumonia was present in only 43.8% of CA-CPPI and 27.3% of HA-CPPI. Of the 153 different bacterial strains cultured, Streptococcus species (32.9%) especially viridans streptococci group were most common in CA-CPPI, whereas HA-CPPI was most often associated with Staphylococcus aureus (11.6%) and Gram-negative (31.9%) infections. Mortality was high during hospitalization (CA-CPPI 13.4% vs HA-CPPI 16.6%; P = 0.417) and at 1 year (CA-CPPI 32.4% vs HA-CPPI 45.5%; P = 0.006). Conclusion: This is the first large multicentre epidemiological study of pleural infection in Australian adults and includes the largest cohort of HA-CPPI published to date. CPPI is caused by a diverse range of organisms which vary between CA and HA sources. CPPI is a poor prognostic indicator both in the short term and in the subsequent 12 months.